Conventional Fractionation Group Research Articles

Postoperative complications of hypofractionated and conventional fractionated radiation therapy in patients with implant-based breast reconstruction: A systematic review and meta-analysis

IntroductionPost-mastectomy radiation therapy is an important component of adjuvant therapy for high-risk patients. However, radiation to reconstructed breasts can cause various complications. Recently, hypofractionated (HF) protocols have been adopted in several countries. Here, we aimed to assess the impact of HF protocols on implant-reconstructed breasts through a meta-analysis and systematic review of the currently available literature. MethodsRecords published until August 2023 were systematically searched in PubMed, Cochrane Library, and EMBASE databases. Keywords included hypofractionation radiotherapy, mastectomy, and breast reconstruction. Studies that utilized HF and conventional fractionation (CF) after prosthetic reconstruction were selected. Due to the rarity of events in outcomes, Mantel-Haenszel's odds ratios were calculated using a fixed-effect model to compare the complication rates between HF and CF groups. For analysis with high heterogeneity, a random effect model was used. ResultsSeven articles with 924 implant reconstructions, in which 506 (54.8 %) underwent HF were included. HF patients received 43.8 Gy on average, while CF patients received 51.2 Gy. Mean follow-up ranged from 10.6 to 35 months. Seven studies were included in the meta-analysis. HF groups had a significantly lower risk of capsular contracture (OR 0.25, 95 % CI 0.11–0.55), major revision surgery (OR 0.19, 95 % CI 0.05–0.80), and wound dehiscence (OR 0.24, 95 % CI 0.07–0.78) compared to CF groups. The risks of other complications were not statistically significant. ConclusionThis study indicates that HF protocols are associated with fewer complications than CF protocols in implant-reconstructed patients. These findings suggest that the application of HF PMRT in implant-reconstructed patients with breast cancer is plausible.

A nationwide study of breast reconstruction after mastectomy in patients with breast cancer receiving postmastectomy radiotherapy: comparison of complications according to radiotherapy fractionation and reconstruction procedures

BackgroundWe examined the patterns of breast reconstruction postmastectomy in breast cancer patients undergoing postmastectomy radiotherapy (PMRT) and compared complications based on radiotherapy fractionation and reconstruction procedures.MethodsUsing National Health Insurance Service (NHIS) data (2015–2020), we analysed 4669 breast cancer patients with PMRT and reconstruction. Using propensity matching, cohorts for hypofractionated fractionation (HF) and conventional fractionation (CF) were created, adjusting for relevant factors and identifying grade ≥3 complications.ResultOf 4,669 patients, 30.6% underwent HF and 69.4% CF. The use of HF has increased from 19.4% in 2015 to 41.0% in 2020. Immediate autologous (32.9%) and delayed two-stage implant reconstruction (33.9%) were common. Complication rates for immediate (N = 1286) and delayed two-stage (N = 784) reconstruction were similar between HF and CF groups (5.1% vs. 5.4%, P = 0.803, and 10.5% vs. 10.7%, P = 0.856, respectively) with median follow-ups of 2.5 and 2.6 years. HF showed no increased risk of complications across reconstruction methods.ConclusionA nationwide cohort study revealed no significant difference in complication rates between the HF and CF groups, indicating HF for reconstructed breasts is comparable to CF. However, consultation regarding the fractionation for reconstructed breast cancer patients may still be necessary.

Hypofractionated re-irradiation for diffuse intrinsic pontine glioma.

Re-irradiation (reRT) increases survival in locally recurrent diffuse intrinsic pontine glioma (DIPG). There is no standard dose and fractionation for reRT, but conventional fractionation (CF) is typically used. We report our institutional experience of reRT for DIPG, which includes hypofractionation (HF). We reviewed pediatric patients treated with brainstem reRT for DIPG at our institution from 2012 to 2022. Patients were grouped by HF or CF. Outcomes included steroid use, and overall survival (OS) was measured from both diagnosis and start of reRT. Of 22 patients who received reRT for DIPG, two did not complete their course due to clinical decline. Of the 20 who completed reRT, the dose was 20-30Gy in 2-Gy fractions (n=6) and 30-36Gy in 3-Gy fractions (n=14). Median age was 5years (range: 3-14), median interval since initial RT was 8months (range: 3-20), and 12 received concurrent bevacizumab. Median OS from diagnosis was 18months [95% confidence interval: 17-24]. Median OS from start of reRT for HF versus CF was 8.2 and 7.5months, respectively (p=.20). Thirteen (93%) in the HF group and three (75%) in the CF group tapered pre-treatment steroid dose down or off within 2months after reRT due to clinical improvement. There was no significant difference in steroid taper between HF and CF (p=.4). No patients developed radionecrosis. reRT with HF achieved survival duration comparable to published outcomes and effectively palliated symptoms. Future investigation of this regimen in the context of new systemic therapies and upfront HF is warranted.

Pattern and Complication of Reconstructed Breast Cancer Patients Who Received Postmastectomy Radiotherapy in the National Health Insurance Service Cohort

This study aimed to analyze the nationwide pattern of reconstruction after mastectomy in patients with breast cancer who received postmastectomy radiotherapy (PMRT) and to compare complications according to fractionation and reconstruction procedures. By using claim data from the National Health Insurance Service (NHIS) database, we analyzed breast cancer patients who received PMRT and underwent reconstruction between 2015 and 2020. We defined the grade ≥ 3 complications as the primary endpoint which involved hospital admission to the plastic surgery department. The complication was identified by using the procedure code for debridement and the International Classification of Diseases 10th codes for wound infections, dehiscence, necrosis, and mechanical complication of breast prosthesis and implant. The propensity score matching method was adopted to constitute the matched cohort between the hypofractionated fractionation (HF) and the conventional fractionation (CF), adjusted for age, diabetes, hypertension, obesity, smoking history, PMRT technique, use of bolus, year of PMRT delivery, and reconstruction method. Logistic regression was performed to evaluate the association between complication and variables. Altogether 4,553 patients were analyzed: 1,395 (30.6%) in the HF group and 3,158 (69.4.%) in the CF group. The use of HF has steadily increased from 20.1% in 2015 to 42.2% in 2020. Immediate implant reconstruction (36.8%) method was the most frequently used, followed by immediate autologous (33.3%) and two-stage implant reconstruction methods (19.6%). In the matched cohort (N = 2,052), the major complication rate was not significantly different between the HF group and the CF group (5.9% [60/1,026] vs. 5.4% [55/1,026], P = 0.568) with the median follow-up of 30.9 months (range, 6.0-82.1). Surgical debridement was performed in 3.3% [34/1026] of the HF group and 3.5% [36/1026] of the CF group (P = 0.808). HF was not associated with major complications (odds ratio (OR) 1.09, 95% CI 0.75-1.59, P = 0.128). In a nationwide insurance cohort, the complication rate was not significantly different between the HF group and the CF group. Our data suggest HF for reconstructed breasts is comparable to CF. However, consultation for fractionation regimen for reconstructed breast cancer patients may be still required at time of consideration of PMRT.

Practice Patterns and Disparities of Fractionation Schemes for Post-Mastectomy Comprehensive Nodal Irradiation

Hypofractionated (HF) radiotherapy is the established standard of care for whole breast irradiation and is being investigated for comprehensive nodal irradiation, but appropriate patient selection for the latter is currently undefined. This study aims to report national practice patterns and patient selection for HF comprehensive nodal irradiation compared to conventional fractionation (CF). The hypothesis is that the rate of HF for comprehensive nodal irradiation in breast cancer has been increasing over time and is more likely to be offered to disparate demographic populations. We queried the National Cancer Database and identified 128,693 patients who received comprehensive nodal irradiation between 2008-2016 in the United States. No patient who underwent lumpectomy received HF nodal irradiation; therefore, only post-mastectomy patients were included in this study. After the exclusion, 29,053 post-mastectomy patients with adjuvant comprehensive nodal irradiation remained. A multivariable binomial regression analysis between HF and CF patients was performed. Of the patients identified, 1,910 received HF (6.57%), and 27,143 received CF (93.43%) radiotherapy. All patients had locally advanced breast cancer treated with mastectomy, lymph node dissection, adjuvant radiation, and +/- chemotherapy. The median dose in the HF group was 4,256 cGy in 16 fractions, and in the CF group was 6,040 cGy in 33 fractions. HF rate grew from 3.56% in 2004-2007, 5.29% in 2008-2011, 7.42% in 2012-2013, and 12.05% in 2014-2016. HF was favored in older patients (median age 66 vs. 51, OR = 1.16, 95% Cl 1.11-1.22) and those who lived in suburban or rural regions compared to urban or metropolitan regions (OR = 9.48, 95% CI 1.17-76.9). However, there was no correlation when distance from treatment site was evaluated as a continuous variable. A "boost" dose was used in only 10.58% of HF patients compared to 54.6% of CF patients (OR = 0.17, 95% Cl 0.14-0.21). Chemotherapy was delivered in 36.91% of HF patients compared to 78.14% of CF patients (OR = 0.77, 95% Cl 0.59-0.99). There were no statistically significant correlates of either fractionation scheme for breast laterality, stage, grade, or receptor status. Notably, other than population density and age, demographic factors including race, Hispanic origin, insurance type, median income, and education level demonstrated no correlation with radiation fractionation scheme. HF for comprehensive nodal irradiation in breast cancer is still uncommon but growing in popularity. Currently, HF is more likely to be used in elderly patients and lower population density centers and less likely to be used in those determined to benefit from receipt of a boost or chemotherapy.

Conventional versus hypofractionated postmastectomy proton radiotherapy in the USA (MC1631): a randomised phase 2 trial

Proton therapy is under investigation in breast cancer as a strategy to reduce radiation exposure to the heart and lungs. So far, studies investigating proton postmastectomy radiotherapy (PMRT) have used conventional fractionation over 25-28 days, but whether hypofractionated proton PMRT is feasible is unclear. We aimed to compare conventional fractionation and hypofractionation in patients with indications for PMRT, including those with immediate breast reconstruction. We did a randomised phase 2 trial (MC1631) at Mayo Clinic in Rochester (MN, USA) and Mayo Clinic in Arizona (Phoenix, AZ, USA) comparing conventional fractionated (50 Gy in 25 fractions of 2 Gy [relative biological effectiveness of 1·1]) and hypofractionated (40·05 Gy in 15 fractions of 2·67 Gy [relative biological effectiveness of 1·1]) proton PMRT. All patients were treated with pencil-beam scanning. Eligibility criteria included age 18 years or older, an Eastern Cooperative Oncology Group performance status of 0-2, and breast cancer resected by mastectomy with or without immediate reconstruction with indications for PMRT. Patients were randomly assigned (1:1) to either conventional fractionation or hypofractionation, with presence of immediate reconstruction (yes vs no) as a stratification factor, using a biased-coin minimisation algorithm. Any patient who received at least one fraction of protocol treatment was evaluable for the primary endpoint and safety analyses. The primary endpoint was 24-month complication rate from the date of first radiotherapy, defined as grade 3 or worse adverse events occurring from 90 days after last radiotherapy or unplanned surgical interventions in patients with immediate reconstruction. The inferiority of hypofractionation would not be ruled out if the upper bound of the one-sided 95% CI for the difference in 24-month complication rate between the two groups was greater than 10%. This trial is registered with ClinicalTrials.gov, NCT02783690, and is closed to accrual. Between June 2, 2016, and Aug 23, 2018, 88 patients were randomly assigned (44 to each group), of whom 82 received protocol treatment (41 in the conventional fractionation group and 41 in the hypofractionation group; median age of 52 years [IQR 44-64], 79 [96%] patients were White, two [2%] were Black or African American, one [1%] was Asian, and 79 [96%] were not of Hispanic ethnicity). As of data cutoff (Jan 30, 2023), the median follow-up was 39·3 months (IQR 37·5-61·2). The median mean heart dose was 0·54 Gy (IQR 0·30-0·72) for the conventional fractionation group and 0·49 Gy (0·25-0·64) for the hypofractionation group. Within 24 months of first radiotherapy, 14 protocol-defined complications occurred in six (15%) patients in the conventional fractionation group and in eight (20%) patients in the hypofractionation group (absolute difference 4·9% [one-sided 95% CI 18·5], p=0·27). The complications in the conventionally fractionated group were contracture (five [12%] of 41 patients]) and fat necrosis (one [2%] patient) requiring surgical intervention. All eight protocol-defined complications in the hypofractionation group were due to infections, three of which were acute infections that required surgical intervention, and five were late infections, four of which required surgical intervention. All 14 complications were in patients with immediate expander or implant-based reconstruction. After a median follow-up of 39·3 months, non-inferiority of the hypofractionation group could not be established. However, given similar tolerability, hypofractionated proton PMRT appears to be worthy of further study in patients with and without immediate reconstruction. The Department of Radiation Oncology, Mayo Clinic, Rochester, MN, the Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA, and the US National Cancer Institute.

Abstract GS4-05: Phase II randomized trial of conventional versus hypofractionated post-mastectomy proton radiotherapy

Abstract Purpose/Objectives: Proton therapy is under investigation in breast cancer as a strategy to reduce heart and lung exposure, which is associated with late cardiopulmonary adverse events and secondary malignancy. To date, studies investigating postmastectomy radiotherapy (PMRT) with protons have used conventional fractionation. We hypothesized that condensing treatment to 15 fractions would be safe based on evidence that breast cancer is more sensitive to higher dose fractions than surrounding normal tissues. Materials/Methods: We conducted a randomized non-inferiority phase II trial comparing conventional and hypofractionated proton PMRT with primary endpoint of 24-month complication rate (defined as grade 3 or higher late adverse events using CTCAE, v 4.0 and/or unplanned surgical intervention in patients undergoing mastectomy with reconstruction). With a 10% non-inferiority margin the study ensured 80% power and had a one sided-type I error rate of 0.05. Cardiotoxicity was assessed with serial transthoracic conventional and 2-dimensional speckle tracking echocardiography (2D-STE). Eligibility included age ≥ 18 years with non-inflammatory breast cancer resected by mastectomy with indications for PMRT. Assignment of treatments was balanced with respect to immediate breast reconstruction (IBR). Conventional fractionation group received 50 Gy in 25 fractions of 2 Gy, and hypofractionation group received 40.05 Gy in 15 fractions of 2.67 Gy (RBE 1.1). Target volume included the chest wall and axillary, supraclavicular, and internal mammary lymph nodes. All patients were treated with multi-field optimized pencil beam scanning (intensity modulated proton therapy). Results: Between 2016 and 2018, 82 patients were enrolled and randomized (41 conventional, 41 hypofractionation). Median patient age was 52 years. 32.9% were staged T3-T4 and 79.3% node positive at diagnosis. 57 of 82 patients (69.5%) elected IBR. The median mean heart dose was 0.49 Gy and the median ipsilateral lung volume receiving 40% of prescription or greater (V40%) was 13.6%. No significant changes on conventional or 2D-STE at end-of-treatment or 3-month follow-up compared to baseline were observed. The rate of ≥ grade 2 acute dermatitis was lower with hypofractionation (44% vs 15%, p = 0.006). Other ≥ grade 2 acute adverse events including esophagitis (0 vs 5%), infection (5% vs 2.4%) and skin hyperpigmentation (7.3% vs 4.8%) were not significantly different between the two arms. With a median follow-up of 38.3 months, the 24-month complication rate was conventional 14.6% vs hypofractionation 17.1% (absolute difference 2.4%, p=0.17, 95% CI [-, 15.7%]). In patients with IBR, 6 of 28 (21.4%) conventional and 7 of 29 (24.1%) hypofractionated patients developed complications (p =0.80). There was no significant difference in 3-year disease-free survival between the conventional (89.4%; 95% CI 80.0 – 99.8%) and hypofractionated (92.4%, 95% CI 84.5 – 100.0%) arms (p = 0.91). One local recurrence occurred in the hypofractionated arm simultaneous with regional and distant relapse. The remaining 6 recurrences were isolated distant events. Conclusions: Proton PMRT provided excellent locoregional control and normal tissue sparing. There were no subclinical echocardiographic changes indicative of radiation-induced cardiac dysfunction. Hypofractionation resulted in comparable disease control, tolerability and reconstruction outcomes as conventional fractionation. Although non-inferiority of hypofractionation could not be established based on the upper bound of the 95% confidence interval for complication rate being greater than 10%, both conventional and hypofractionation may be considered appropriate regimens for ongoing phase 3 randomized trials comparing photon and proton radiotherapy. Citation Format: Robert Mutter, Sharmila Giri, Briant Fruth, Nicholas Remmes, Aman Anand, Kathryn Ruddy, Hector Villarraga, Sebastian Santos Patarroyo, Elizabeth Yan, Kenneth Merrell, Lisa McGee, Tamara Vern-Gross, Bradley Stish, Robert Gao, Judy C. Boughey, Sean Park, Kimberly Corbin, Carlos Vargas. Phase II randomized trial of conventional versus hypofractionated post-mastectomy proton radiotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-05.

Prostate Magnetic Resonance Imaging Delta-Radiomics during Image-Guided Conventional Fractionation and Stereotactic Ablative Radiotherapy

<h3>Purpose/Objective(s)</h3> The ability to detect changes during radiotherapy to the prostate with radiomics techniques may allow prediction of clinical outcomes and influence subsequent treatment choices. In this feasibility study, we aimed to assess changes in features (delta-radiomics) across a course of treatment in men undergoing MRI-guided radiotherapy for prostate cancer. We compared changes between conventional fractionation and ultrahypofractionated SABR treatment. <h3>Materials/Methods</h3> MRI images from men receiving radiotherapy only to the prostate on an MR Linac developed by a precision radiation medicine company in a large tertiary cancer center were analyzed. Treatment localization scans were transferred from one treatment planning system, (from a precision radiation medicine company, Crawley UK) to a different treatment planning system. The whole prostate was re-contoured from T2 sequences obtained at fraction 1 and at 4 evenly spread time points. For SABR this was at fractions 2 to 5 and for conventional fractionation at fraction 5, 10, 15 and 20 respectively. Radiomics data was extracted with an open-source software platform. Data for energy, entropy, kurtosis and shape parameters were analyzed using a linear mixed-effects model to explore changes over time within a patient (within subject variability) as well as between subject variability between men treated with conventional fractionation v SABR. <h3>Results</h3> 40 men were analyzed, 20 receiving conventional fractionation (60Gy in 20 fractions over four weeks) and 20 receiving SABR (36.25Gy in 5 fractions over two weeks) respectively. Mean age was 69.3years (range 53-82) and mean PSA at diagnosis 9.37 (range 2.18 – 32). Gleason score was 6 in 1 patient, 7 in 38 patients and 8 in 1 patient. Five men did not receive any androgen deprivation therapy prior to radiotherapy (3 patients receiving conventional fractionation, 2 receiving SABR). The only radiomics variable that showed a time-trend was first order entropy in the conventional fractionation group, not in the SABR group (p<0.001). Treatment type was not a significant covariate for any of the other metrics. I.e., in long fractionation a reduction in entropy is observed during treatment, showing the prostate gray values become more homogeneous over time. <h3>Conclusion</h3> Our analyses showed a reduction in entropy for conventional fractionation rather than ultrahypofractionated SABR suggesting that image changes only become apparent over longer treatment courses. During SABR, no radiomics features showed a significant trend. These may still develop on later imaging as changes in cell appearance from DNA damage may only be apparent over time. Further analyses are planned to explore the relationship between delta radiomics and clinical outcomes and whether entropy can be used as an imaging biomarker.

Quality Assurance in the Dummy Run of a Multicenter Randomized Trial of POstmastectomy radioThErapy in Node-posiTive breast cancer with or without Internal mAmmary nodaL irradiation (POTENTIAL)

<h3>Purpose/Objective(s)</h3> To present the results of the dummy run of POTENTIAL (Clinical trials.gov identifier NCT04320979), a multicenter phase III randomized study, investigating the compliance to the protocol guidelines of participating institutes and evaluating the effect of quality control programs in improving interinstitutional consistency. <h3>Materials/Methods</h3> Prior to protocol activation, all the participating institutes were asked to make a treatment plan for a breast patient with Internal mammary nodal (IMN) irradiation according to the protocol of the trial. CT images and outlines of the target volumes and the organs at risk (OAR) are provided by sponsor in Dicom-RT. The plan quality was evaluated by trail QA committee based on dose distribution, dose volume histogram (DVH) and field parameters, etc. After evaluation, recommendations for improvement of the plan quality would be forwarded to participants if a plan revision was required. Thereafter, dose verifications were completed to ensure the accuracy of treatment delivery. <h3>Results</h3> A number of deviations from trail protocol were observed by plan review. The average D95% of the CW and the IMN target volume were approximately 10% lower than prescribed dose for the conventional fractionation group (50 Gy in 25 fractions) and 3% for the hypofractionation group (43.5 Gy in 15 fractions). After revision, the dose coverage of the targets was significantly improved. The average D95% of the CW and the IMN target volume reached higher than 49 Gy and 43 Gy for the conventional fractionation group and the hypofractionation group, respectively. The revised plans also provided better OAR dose sparing. <h3>Conclusion</h3> The QA program in the dummy run had a positive effect in improving interinstitutional consistency, since the deviations from trail protocol were significantly decreased by plan review and revision.

CLRM-06 PROSPECTIVE CLINICAL STUDY OF CONVENTIONALLY FRACTIONATED CONCURRENT CHEMORADIOTHERAPY AND HYPOFRACTIONATED CONCURRENT CHEMORADIOTHERAPY AFTER THE SURGERY OF HIGH-GRADE GLIOMAS

PURPOSETo observe and evaluate the efficacy and safety of conventional fractionated concurrent chemoradiotherapy and hypofractionated concurrent chemoradiotherapy for adjuvant treatment of newly treated high-grade glioma. METHODFor newly treated patients with high-grade gliomas with WHO grade III-IV, all patients started concurrent chemoradiotherapy within 1 month after surgery, and received concurrent temozolomide 75 mg/m2 during radiotherapy until the end of radiotherapy. Sequential temozolomide chemotherapy at 200 mg/m2 for at least 6 cycles. All patients were randomly divided into groups, one group was given conventional fractional irradiation, 60Gy/30f in high-risk areas, 46Gy/23f in low-risk areas, and the other group was given low-fractionated irradiation, 53Gy/15f in high-risk areas, and 53Gy/15f in low-risk areas 43Gy/15f. The overall survival (OS), progression-free survival (PFS), radiation-induced cerebral edema and radiation-induced brain necrosis were evaluated. RESULTAs of December 31, 2022, a total of 60 patients were enrolled, including 30 in the conventional fractionation treatment group and 30 in the hypofractionated treatment group. At present, 58 patients survived and 2 died, 2 in the conventional fractionation group, one due to tumor recurrence and one due to cardiac accident; 7 patients recurred, including 4 in the conventional fractionation group and 3 in the low fractionation group. Radiation cerebral edema occurred in 9 cases, 6 cases in the hypofractionated group and 3 cases in the conventional fractionation group, all of which were completely relieved after dehydration with mannitol, which did not affect the progress of radiotherapy. No radiation necrosis occurred during follow-up. CONCLUSIONCompared with the standard stupp regimen, using 53Gy/15f in the high-risk area and 43Gy/15f in the low-risk area as an adjuvant therapy with concurrent temozolomide and sequential temozolomide, there was no increased risk of disease recurrence, no increased risk of death, and no increased risk of death.

Hypofractionated or Conventionally Fractionated Adjuvant Radiotherapy After Regional Lymph Node Dissection for High-Risk Stage III Melanoma

AimsAdjuvant radiotherapy can be beneficial after regional lymph node dissection for high-risk stage III melanoma, as it has been shown to reduce the risk of recurrence in the node field. However, the optimal fractionation schedule is unknown and both hypofractionated and conventionally fractionated adjuvant radiotherapy are used. The present study examined the oncological outcomes of these two approaches in patients treated in an era before effective systemic immunotherapy became available. Materials and methodsThis retrospective cohort study involved 335 patients with stage III melanoma who received adjuvant radiotherapy after therapeutic regional lymph node dissection for metastatic melanoma between 1990 and 2011. Information on tumour characteristics, radiotherapy doses and fractionation schedules and patient outcomes was retrieved from the institution's database and patients' medical records. ResultsHypofractionated radiotherapy (median dose 33 Gy in six fractions over 3 weeks) was given to 95 patients (28%) and conventionally fractionated radiotherapy (median dose 48 Gy in 20 fractions over 4 weeks) to 240 patients (72%). Five-year lymph node field control rates were 86.0% (95% confidence interval 78.4–94.4%) for the hypofractionated group and 85.5% (95% confidence interval 80.5–90.7%) for the conventional fractionation group (P = 0.87). There were no significant differences in recurrence-free survival (RFS) (41.7%, 95% confidence interval 32.5–53.5 versus 31.9%, 95% confidence interval 26.1–38.9; P = 0.18) or overall survival (41.2%, 95% confidence interval 32.1–52.8 versus 45.0%, 95% confidence interval 38.7–52.4; P = 0.77). On multivariate analysis, extranodal spread was associated with decreased RFS (P = 0.04) and the number of resected lymph nodes containing metastatic melanoma was associated with decreased RFS (P = 0.0006) and overall survival (P = 0.01). ConclusionLymph node field control rates, RFS and overall survival were similar after hypofractionated and conventionally fractionated adjuvant radiotherapy. The presence of extranodal spread and an increasing number of positive lymph nodes were predictive of an unfavourable outcome.

Hyperfractionation versus Conventional Fractionation of Preoperative Intensity-Modulated Radiotherapy with Oral Capecitabine in Locally Advanced Mid-Low Rectal Cancer: A Propensity Score Matching Study.

Purpose In theory, the hyperfractionated radiotherapy can enhance biological effect dose against tumor and alleviate normal tissue toxicity. This study is to assess the efficacy and safety of preoperative hyperfractionated intensity-modulated radiotherapy (IMRT) with oral capecitabine in patients with locally advanced rectal cancer (LARC). Methods We retrospectively screened patients with LARC from January 2015 to June 2016. Patients that received hyperfractionated IMRT or conventional fractionated IMRT were eligible in the hyperfractionation (HF) group or conventional fractionation (CF) group, respectively. The primary outcome was the complete response rate. Secondary outcomes included toxicity, postoperative complications, anus-reservation operation rate, local recurrence and distant metastases rate, overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS). Results 335 patients were included in the analysis. The complete response rate for the hyperfractionated and conventional fractionated IMRT was 20.41% vs. 23.47% (P = 0.583). The anus-reservation operation rate was 68.37% vs. 65.31% (P = 0.649). There were no cases of grade 4 toxicity during radiotherapy; the rate of grade 3 toxicity and postoperative complications was both comparable between groups. However, in the CF group, more patients had a second operation due to complications (0.0% vs. 5.68%, P = 0.011). The cumulative local regional recurrence and distant metastases rates of the HF group and CF group were 5.10% vs. 9.18% (P = 0.267) and 22.45% vs. 24.49% (P = 0.736), respectively. The 5-year OS, CSS, and DFS in the HF group and CF group were 86.45% vs. 73.30% (P = 0.503), 87.34% vs. 75.23% (P = 0.634), and 70.80% vs. 68.11% (P = 0.891), respectively. Conclusions The preoperative hyperfractionated IMRT with oral capecitabine, with an acceptable toxicity and favorable response and survival, could reduce the rate of secondary surgery.

Disease Control After Hypofractionation Versus Conventional Fractionation for Triple Negative Breast Cancer: Comparative Effectiveness in a Large Observational Cohort

Questions remain about whether moderately hypofractionated whole-breast irradiation is appropriate for patients with triple-negative breast cancer. Using the prospective database of a multicenter, collaborative quality improvement consortium, we identified patients with node-negative, triple-negative breast cancer who received whole-breast irradiation with either moderate hypofractionation or conventional fractionation. Using inverse probability of treatment weighting (IPTW), we compared outcomes using the Kaplan-Meier product-limit estimation method with Cox regression models estimating the hazard ratio for time-to-event endpoints between groups. The sample included 538 patients treated at 18 centers in 1 state in the United States, of whom 307 received conventionally fractionated whole-breast irradiation and 231 received moderately hypofractionated whole-breast irradiation. The median follow-up time was 5.0 years (95% confidence interval [CI], 4.77-5.15 years). The 5-year IPTW estimates for freedom from local recurrence were 93.6% (95% CI, 87.8%-96.7%) in the moderate hypofractionation group and 94.4% (95% CI, 90.3%-96.8%) in the conventional fractionation group. The hazard ratio was 1.05 (95% CI, 0.51-2.17; P=.89). The 5-year IPTW estimates for recurrence-free survival were 87.8% (95% CI, 81.0%-92.4%) in the moderate hypofractionation group and 88.4% (95% CI 83.2%-92.1%) in the conventional fractionation group. The hazard ratio was 1.02 (95% CI, 0.62-1.67; P=.95). The 5-year IPTW estimates for overall survival were 96.6% (95% CI, 92.0%-98.5%) in the moderate hypofractionation group and 93.4% (95% CI, 88.7%-96.1%) in the conventional fractionation group. The hazard ratio was 0.65 (95% CI, 0.30-1.42; P=.28). Analysis of outcomes in this large observational cohort of patients with triple-negative, node-negative breast cancer treated with whole-breast irradiation revealed no differences by dose fractionation. This adds evidence to support the use of moderate hypofractionation in patients with triple-negative disease.

Short-term efficacy and long-term survival of limited-stage small cell lung cancer treated with large fractionation radiotherapy and conventional fractionation radiotherapy.

e20586 Background: Hyperfractionation (1.5Gy per dose twice a day, total dose 45Gy) or conventional fractionation (2Gy per dose once a day, total dose 60-70Gy) is the recommended dose fractionation for LS-SCLC. However, the optimal segmentation mode and dose of radiotherapy have not been determined. In this study, we evaluated the short-term efficacy and toxic and side effects of macrofractionation to explore the feasibility of macrofractionation radiotherapy in the treatment of LS-SCLC patients. Methods: From May 2011 to February 2020, 52 patients with LS-SCLC admitted to Jiangsu Cancer Hospital were retrospectively analyzed. The patients were divided into two groups according to the dose separation mode, including 29 cases in the large division group (3-4Gy per dose once a day, total dose 45-60Gy) and 23 cases (2Gy per dose once a day, total dose 50-68Gy) in the conventional division group. The short-term efficacy, 1-year survival rate and some other aspects of the two groups were compared. Results: The short-term overall response rate of large segmentation group was 79.3%, and there was significant difference compared with 52.2% of conventional segmentation group ( χ2 =4.293, P&lt;0. 05) (Table). The 1-year survival rate of the large segmentation group was similar to that of the conventional segmentation group (82.8% vs．82.6%). The median survival time of large segment group was 30 months,which was not significantly different from the 34 months of conventional segment group (χ2=0.417, P&gt;0.05). In terms of the effect of the two fractionated dose modes on long survival, 31.0% of patients in the large fractionation group survived more than 48 months, compared with only 13% in the conventional fractionation group. In addition, in the subgroup analysis of this study, it was found that compared with conventional fractionation radiotherapy, patients aged 45-65 years with ECOG score of 0-1 and lesions less than 5cm before radiotherapy could obtain more significant survival benefit from large fractionation radiotherapy, with statistically significant difference between the two groups (χ2=4.874, P&lt;0.05). Conclusions: Large segmentation radiotherapy in the treatment of patients with LS-SCLC can improve the therapeutic effect and prolong the survival, especially for patients aged 45-65 years with ECOG score of 0-1 and lesions less than 5cm before radiotherapy , the survival benefit is more significant. In addition, large fractionated radiotherapy showed certain advantages in the long-term survival of patients with LS-SCLC, which is worthy of further clinical application.[Table: see text]

Abstract PS15-17: Hypofractionated versus conventional intensity modulated postmastectomy radiotherapy: Toxicity and quality of life in patients with tissue-expander breast reconstruction

Abstract Introduction: Hypofractionation (HF) in breast cancer is a radiotherapy regimen frequently used in recent years. Greater toxicity has been described in irradiated patients with heterologous breast reconstruction procedures, but it is unknown if this greater toxicity could be avoided by using hypofractionated intensity modulated radiotherapy (IMRT). The objective of this study is to describe the toxicity and complications presented in breast cancer patients that were reconstructed with a tissue expander (EXP) treated with IMRT and to determine if there are differences according to the used fractionation regimen. Method: All patients with breast cancer reconstructed with expander and treated with adjuvant IMRT to the chest wall and regional lymph nodes were included, using conventional fractionation (CF) dose of 50 Gy in 25 fractions or hypofractionated (HF) regimen dose of 45 Gy in 20 fractions. Acute and late toxicity, during treatment and at the end of follow-up, were recorded according to RTOG / EORTC and CTCAE 4.0 criteria and the BREAST Q 2.0 quality of life survey postoperative reconstruction module (QoL) was applied in the last follow-up visit. Results: 33 patients were analyzed. With a median follow-up of 17 months, 31 were treated with Tomotherapy and 2 with VMAT. CF was used in 20 and HF in 13. There was no G3 acute toxicity, and G2 was observed in only 1 patient with HF (7.6%) and in 3 with CF (15%), mainly determined by radiodermatitis. Regarding late toxicity (LT), there was only one G3 event which occurred in a patient with CF and full axillary irradiation. Grade 2 LT was not observed in patients treated with HF, whereas with CF 2 cases (10%) were reported. During the expander period, 1 patient with HF presented a complication (7,6%) and 3 with CF (15%), 2 of the latter required unscheduled surgical intervention (USI). 12 patients in the HF group underwent prosthetic replacement (92%) and 15 in the CF group (75%). After the replacement 4 patients with CF required an USI (26.6%) and none of the patients in the HF group had post replacement complications that required hospitalization. None of the previously mentioned differences were statistically significant. Regarding QoL, the patients with HF had a better late toxicity score, with an average of 96.7 vs. 82.4 points (p &amp;lt;0.005), and better physical well-being of the chest, with an average of 81.7 vs. 66 points, which did not reach statistical significance (p = 0.052). The rest of the scales within the module did not show any differences. Conclusions: Postmastectomy IMRT in patients with heterologous reconstruction is associated with low toxicity and complications. The use of hypofractionation presents a toxicity profile similar to that of conventional fractionation, with a tendency to less frequent complications associated with reconstruction. HF is also associated with a better QoL score in late toxicity and physical well-being of the chest. Prospective studies are required to confirm whether hypofractionation using IMRT could decrease complications and improve quality of life in patients undergoing total mastectomy and tissue-expander breast reconstruction. Citation Format: Ariel Fariña, Dagmar Alfonso, Aroldo Fernandez, Felipe Carvajal, Ana María Ciudad, Celmira Martínez, Camila Pérez, Pablo González, Hugo Marsiglia. Hypofractionated versus conventional intensity modulated postmastectomy radiotherapy: Toxicity and quality of life in patients with tissue-expander breast reconstruction [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS15-17.

Expanding the Utilization of Rectal Spacer Hydrogel for Larger Prostate Glands (>80 cc): Feasibility and Dosimetric Outcomes

PurposeThe Hydrogel Spacer Prospective Randomized Pivotal Trial achieved mean rectoprostatic spacing of 12.6 mm resulting in lowering of rectal V70 from 12.4% (without spacer) to 3.3% (with spacer) in patients with glands up to 80 cm3. The value of this approach in patients with larger glands is inadequately established. This study assesses the feasibility and dosimetric outcomes of perirectal spacing in patients with prostate cancer with larger glands (>80 cm3).Methods and MaterialsBetween January 2017 and December 2019, 33 patients with prostate glands >80 cm3 (mean 108.1 cm3; range, 81.1-186.6 cm3) were treated, 15 with glands >80 to 100 cm3 and 18 >100 cm3. Median follow-up was 10 months (range, 3-26). The median international prostate symptom score was 9 (range, 1-18). Hydrogel was placed under local anesthesia in all cases. Treatment modality included intensity modulated radiation therapy in 15 and proton therapy (PT) in 18 patients. Treatment targeted the prostate plus seminal vesicles in 21 patients and 12 also had elective nodal irradiation. Conventional fractionation (CF) to 78 Gy in 39 fractions was used in 16 and moderate hypofractionation (HF) to 70 Gy in 28 fractions in 17 patients.ResultsIn the CF group, mean rectum (r) V75, 70, 60, 50 was 0.87%, 2.25%, 5.61%, and 10.5%, respectively. For glands >80 to 100 cm3 and >100 cm3, rV70 was 2.55% and 2%, respectively. In HF patients, mean rV65, 63, 60, and 50 was 1.67%, 2.3%, 3.4%, and 8.6%. For glands >80 to 100 cm3 and >100 cm3, rV63 was 2% and 2.56%, respectively. Overall, the mean midgland rectoprostatic hydrogel separation was 9.3 mm (range, 4.7-19.4 mm). All patients tolerated treatment well; no acute grade 2 or higher adverse gastrointestinal events were observed.ConclusionsHydrogel placement is feasible in prostate glands larger than 80 cm3 with favorable dosimetric outcomes.

Ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer (HYPO-RT-PC): patient-reported quality-of-life outcomes of a randomised, controlled, non-inferiority, phase 3 trial

The HYPO-RT-PC trial compared conventionally fractionated radiotherapy with ultra-hypofractionated radiotherapy in patients with localised prostate cancer. Ultra-hypofractionation was non-inferior to conventional fractionation regarding 5-year failure-free survival and toxicity. We aimed to assess whether patient-reported quality of life (QOL) differs between conventional fractionation and ultra-hypofractionation up to 6 years after treatment in the HYPO-RT-PC trial. HYPO-RT-PC is a multicentre, open-label, randomised, controlled, non-inferiority, phase 3 trial done in 12 centres (seven university hospitals and five county hospitals) in Sweden and Denmark. Inclusion criteria were histologically verified intermediate-to-high-risk prostate cancer (defined as T1c-T3a with one or two of the following risk factors: stage T3a; Gleason score ≥7; and prostate-specific antigen 10-20 ng/mL with no evidence of lymph node involvement or distant metastases), age up to 75 years, and WHO performance status 0-2. Participants were randomly assigned (1:1) to conventional fractionation (78·0 Gy in 39 fractions, 5 days per week for 8 weeks) or ultra-hypofractionation (42·7 Gy in seven fractions, 3 days per week for 2·5 weeks) via a minimisation algorithm with stratification by trial centre, T-stage, Gleason score, and prostate-specific antigen. QOL was measured using the validated Prostate Cancer Symptom Scale (PCSS) and European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire (EORTC QLQ-C30) at baseline, the end of radiotherapy, months 3, 6, 12, and 24 after radiotherapy, every other year thereafter up to 10 years, and at 15 years. The primary endpoint (failure-free survival) has been reported elsewhere. Here we report QOL, a secondary endpoint analysed in the per-protocol population, up to 6 years after radiotherapy. The HYPO-RT-PC trial is registered with the ISRCTN registry, ISRCTN45905321. Between July 1, 2005, and Nov 4, 2015, 1200 patients were enrolled and 1180 were randomly assigned (conventional fractionation n=591, ultra-hypofractionation n=589); 1165 patients (conventional fractionation n=582, ultra-hypofractionation n=583) were included in this QOL analysis. 158 (71%) of 223 patients in the conventional fractionation group and 146 (66%) of 220 in the ultra-hypofractionation group completed questionnaires at 6 years. The median follow-up was 48 months (IQR 25-72). In seven of ten bowel symptoms or problems the proportion of patients with clinically relevant deteriorations at the end of radiotherapy was significantly higher in the ultra-hypofractionation group than in the conventional fractionation group (stool frequency [p<0·0001], rush to toilet [p=0·0013], flatulence [p=0·0013], bowel cramp [p<0·0001], mucus [p=0·0014], blood in stool [p<0·0001], and limitation in daily activity [p=0·0014]). There were no statistically significant differences in the proportions of patients with clinically relevant acute urinary symptoms or problems (total 14 items) and sexual functioning between the two treatment groups at end of radiotherapy. Thereafter, there were no clinically relevant differences in urinary, bowel, or sexual functioning between the groups. At the 6-year follow-up there was no difference in the incidence of clinically relevant deterioration between the groups for overall urinary bother (43 [33%] of 132 for conventional fractionation vs 33 [28%] of 120 for ultra-hypofractionation; mean difference 5·1% [95% CI -4·4 to 14·6]; p=0·38), overall bowel bother (43 [33%] of 129 vs 34 [28%] of 123; 5·7% [-3·8 to 15·2]; p=0·33), overall sexual bother (75 [60%] of 126 vs 59 [50%] of 117; 9·1% [-1·4 to 19·6]; p=0·15), or global health/QOL (56 [42%] of 134 vs 46 [37%] of 125; 5·0% [-5·0 to 15·0]; p=0·41). Although acute toxicity was higher for ultra-hypofractionation than conventional fractionation, this long-term patient-reported QOL analysis shows that ultra-hypofractionation was as well tolerated as conventional fractionation up to 6 years after completion of treatment. These findings support the use of ultra-hypofractionation radiotherapy for intermediate-to-high-risk prostate cancer. The Nordic Cancer Union, the Swedish Cancer Society, and the Swedish Research Council.

Hypofractionated Simultaneous Integrated Boost Radiotherapy Versus Conventional Fractionation Radiotherapy of Early Breast Cancer After Breast-Conserving Surgery: Clinical Observation and Analysis.

Purpose: The objective of this retrospective study is to evaluate the efficacy and safety of hypofractionated simultaneous integrated boost radiotherapy for early breast cancer patients undergoing breast-conserving surgery. Methods: A total of 185 women with early breast cancer undergoing breast-conserving surgery were retrospectively divided into hypofractionated simultaneous integrated boost group and conventional fractionation group. Hypofractionated simultaneous integrated boost included 104 patients and the dose of whole-breast radiation reached 42.56 Gy in 16 fractions and simultaneously tumor bed boost to 48 Gy in 16 fractions, which course of radiotherapy was 22 days. The 81 patients of the conventional fractionation group received whole breast radiation to 50 Gy in 25 fractions and followed by tumor bed boost to 10 Gy in 5 fractions, which course of radiotherapy was 40 days. Clinical information including patients’ characteristics, skin toxicity, myelosuppression, radiation pneumonia, and cosmetic effects was recorded to analyze the influence of age, chemotherapy, position, and breast volume on the results of radiotherapy. Results: Hypofractionated simultaneous integrated boost group had no case of recurrence after a median follow-up of 25.6 months (9-47 months)) as compared with 2 after a median follow-up of 33.4 months (25-45 months) in the conventional fractionation group. The 2 groups had similar results in skin toxicity, cosmetic outcomes, and radiation pneumonia. In terms of myelosuppression, grade 1, grade 2, and grade 3 of myelosuppression in the hypofractionated simultaneous integrated boost group accounted for 16.7%, 12.3%, and 3.5% as compared with 30.0%, 21.1%, and 12.3% of the conventional fractionation group, respectively (P = .000). Conclusions: HF-SIB RT is a considerable option in patients after breast-conserving surgery with a lower degree of myelosuppression and shorter treatment time.

Ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer: 5-year outcomes of the HYPO-RT-PC randomised, non-inferiority, phase 3 trial

Hypofractionated radiotherapy for prostate cancer has gained increased attention due to its proposed high radiation-fraction sensitivity. Recent reports from studies comparing moderately hypofractionated and conventionally fractionated radiotherapy support the clinical use of moderate hypofractionation. To date, there are no published randomised studies on ultra-hypofractionated radiotherapy. Here, we report the outcomes of the Scandinavian HYPO-RT-PC phase 3 trial with the aim to show non-inferiority of ultra-hypofractionation compared with conventional fractionation. In this open-label, randomised, phase 3 non-inferiority trial done in 12 centres in Sweden and Denmark, we recruited men up to 75 years of age with intermediate-to-high-risk prostate cancer and a WHO performance status between 0 and 2. Patients were randomly assigned to ultra-hypofractionation (42·7 Gy in seven fractions, 3 days per week for 2·5 weeks) or conventional fractionated radiotherapy (78·0 Gy in 39 fractions, 5 days per week for 8 weeks). No androgen deprivation therapy was allowed. The primary endpoint was time to biochemical or clinical failure, analysed in the per-protocol population. The prespecified non-inferiority margin was 4% at 5 years, corresponding to a critical hazard ratio (HR) limit of 1·338. Physician-recorded toxicity was measured according to the Radiation Therapy Oncology Group (RTOG) morbidity scale and patient-reported outcome measurements with the Prostate Cancer Symptom Scale (PCSS) questionnaire. This trial is registered with the ISRCTN registry, number ISRCTN45905321. Between July 1, 2005, and Nov 4, 2015, 1200 patients were randomly assigned to conventional fractionation (n=602) or ultra-hypofractionation (n=598), of whom 1180 (591 conventional fractionation and 589 ultra-hypofractionation) constituted the per-protocol population. 1054 (89%) participants were intermediate risk and 126 (11%) were high risk. Median follow-up time was 5·0 years (IQR 3·1-7·0). The estimated failure-free survival at 5 years was 84% (95% CI 80-87) in both treatment groups, with an adjusted HR of 1·002 (95% CI 0·758-1·325; log-rank p=0·99). There was weak evidence of an increased frequency of acute physician-reported RTOG grade 2 or worse urinary toxicity in the ultra-hypofractionation group at end of radiotherapy (158 [28%] of 569 patients vs 132 [23%] of 578 patients; p=0·057). There were no significant differences in grade 2 or worse urinary or bowel late toxicity between the two treatment groups at any point after radiotherapy, except for an increase in urinary toxicity in the ultra-hypofractionation group compared to the conventional fractionation group at 1-year follow-up (32 [6%] of 528 patients vs 13 [2%] of 529 patients; (p=0·0037). We observed no differences between groups in frequencies at 5 years of RTOG grade 2 or worse urinary toxicity (11 [5%] of 243 patients for the ultra-hypofractionation group vs 12 [5%] of 249 for the conventional fractionation group; p=1·00) and bowel toxicity (three [1%] of 244 patients vs nine [4%] of 249 patients; p=0·14). Patient-reported outcomes revealed significantly higher levels of acute urinary and bowel symptoms in the ultra-hypofractionation group compared with the conventional fractionation group but no significant increases in late symptoms were found, except for increased urinary symptoms at 1-year follow-up, consistent with the physician-evaluated toxicity. Ultra-hypofractionated radiotherapy is non-inferior to conventionally fractionated radiotherapy for intermediate-to-high risk prostate cancer regarding failure-free survival. Early side-effects are more pronounced with ultra-hypofractionation compared with conventional fractionation whereas late toxicity is similar in both treatment groups. The results support the use of ultra-hypofractionation for radiotherapy of prostate cancer. The Nordic Cancer Union, the Swedish Cancer Society, and the Swedish Research Council.

Outcomes in DCIS Patients Treated with Hypofractionated Whole Breast Radiation Therapy with Integrated Boost Compared to Standard Fractionation with Concomitant Boost

Hypofractionation for ductal carcinoma in situ (DCIS) is not yet formally recommended by national guidelines. We compared outcomes after hypofractionated radiation therapy (HRT) with an integrated boost to conventional fractionation (CRT) with sequential boost for DCIS. We queried our institutional database for DCIS patients treated with whole breast RT after lumpectomy between Jan 2004 and Nov 2015 and followed for greater than 2 years. HRT delivered 2.25 Gy per fraction (fx) to 45 Gy to the whole breast with an integrated 2.8 Gy tumor bed boost per fx for a total of 56 Gy in 20 fx over 4 weeks. CRT delivered 50 Gy in 2 Gy fx to the whole breast plus a sequential 10-16 Gy tumor bed boost. Treatment fields utilized field-in-field tangential design or IMRT. CRT patients were propensity score matched to HRT patients in a 2:1 ratio using age, bra cup size, DCIS grade, histologic subtype (comedo vs non-comedo) and use of endocrine therapy. Toxicity was graded using CTCAE v3 and stratified as early (<6 weeks from RT completion) vs late. Acute toxicity was reported weekly during radiation. Physician reported cosmesis was scored using the Harvard scale (1 excellent, 2 good, 3 fair, 4 poor). Kaplan Meier estimates for ipsilateral invasive/DCIS recurrence at 5 years were calculated. Univariate logistic regression to predict toxicity outcomes employed generalized estimating equations to control for the within subject correlation. Forty-six patients undergoing HRT were eligible and were matched to 92 CRT patients. Median follow-up of all patients was 76 months (range 24-164). Median age was 59 years (40-91). Cup size was B or smaller in 31%. Comedo and grade 3 histology were present in 28% and 46%, respectively. Endocrine therapy was taken by 55%. Final margin status was close or positive in 12% and 2% of patients, respectively. There were no statistically significant differences in any demographic, clinical or treatment characteristics following matching. Recurrence free survival after CRT and HRT was 93.7% and 97.8% at 5 years (p=0.74), respectively. In patients who had cosmesis reported (61% available), median final score was 1.27 for CRT and 1.25 for HRT (chi square p=0.96).Abstract TU_4_3355; Table 1VariableHRT%CRT%Odds RatioP-valueCIAcute skin color change19%38%0.400.030.17-0.93All acute toxicity ≥ Grade 222%52%0.25<0.010.12-0.55Acute tissue complications ≥ Grade 22%26%0.06<0.010.01-0.51All late toxicity ≥ Grade 22%5%0.390.300.06-2.32Late tissue complications ≥ Grade 22%4%0.490.420.09-2.77 Open table in a new tab In this single institution experience, DCIS patients treated with HRT with concurrent boost experienced similar or improved toxicity compared to CRT matched controls. Rates of recurrence were similar between CRT and HRT groups. HRT toxicity data and rate of recurrence was consistent with other investigations utilizing HRT and boost.