Sparing Intensity Modulated Radiation Therapy Research Articles

Dosimetric Evaluation of Hippocampus Sparing Intensity Modulated Radiation Therapy in Patients With Stage T1-T2 and Stage T3-T4 Nasopharyngeal Carcinoma

PurposeTo compare the hippocampus (HPC) dose reduced by HPC-sparing IMRT plans between nasopharyngeal carcinoma (NPC) patients of stages T1-T2 and T3-T4, and to investigate the correlation between the dose of the hippocampus and the volume of PTVnx70 (the planning target volume of the primary tumor in the nasopharynx received 70 Gy). Methods and MaterialsFifty-eight NPC patients were retrospectively evaluated. HPC non-sparing IMRT or sparing IMRT for each patient was designed according to the protocol for NPC. Dose-volume histogram (DVH) was used to evaluate the IMRT plans for each patient. The difference values of HPC parameters (e.g., Dmin[NS] - Dmin[S]) between HPC sparing and non-sparing plans in stage T1-T2 Group and stage T3-T4 Group were compared. The correlations between the dose of the hippocampus and the volume of PTVnx70 were analyzed. ResultsThere was no significance between HPC-sparing and non-sparing IMRT plans. Compared with the HPC non-sparing plans, the HPC sparing plans significantly decreased both dosimetric and volumetric parameters for the HPC (P < 0.05), except for Dmin, D98%, and V5. The medians of Dmedian[NS] - Dmedian[S], Dmean[NS] - Dmean[S], D40%[NS] - D40%[S], V30[NS] - V30[S], V40[NS] - V40[S] and V50[NS] - V50[S] in the T1-T2 Group were significantly lower than in the T3-T4 Group (P < 0.05), respectively. Both dosimetric and volumetric parameters for the HPC were positively correlated with the volume of PTVnx70 in HPC-sparing and non-sparing plans (P < 0.05). The volume of PTVnx70 was positively correlated with Dmedian[NS] - Dmedian[S], Dmean[NS] - Dmean[S], D40%[NS] - D40%[S], V40[NS] - V40[S] and V50[NS] - V50[S] (P < 0.05). ConclusionsHPC-sparing IMRT plans may play a more significant role in decreasing Dmedian, Dmean, D40%, and V30 ∼ V50 of HPC in NPC patients with stages T3-T4 than those in stages T1-T2. PTVnx70 volume of NPC patients are positively correlated with all dosimetric and volumetric parameters of HPC and the reduction of specific dosage parameters by HPC-sparing IMRT plans.

Reduced frequency and severity of radiation esophagitis without marginal failure risk by contralateral esophagus sparing IMRT in stage III non-small cell lung cancer patients undergoing definitive concurrent chemoradiotherapy

PurposeRadiation esophagitis is frequent and annoying toxicity in high dose thoracic radiation therapy. Contalateral esophagus sparing intensity modulated radiation therapy (CES-IMRT) has been proposed to mitigate this problem, and this is to report the impact of CES-IMRT in definitive concurrent chemoradiotherapy (dCCRT) for lung cancer patients. Materials and methodsFrom January 2021 till May 2023, 183 stage III non-small cell lung cancer patients underwent dCCRT. Esophagus was located within 1 cm from internal target volume in 159 patients. We comparatively evaluated the frequency and severity of esophagitis by pain-killer usage, analgesic quantification algorithm (AQA) score, and failure patterns in 159 CES-necessary patients. ResultsAll patients underwent dCCRT (66 Gy in 30 fractions with concurrent chemotherapy). Actual CES-IMRT application was determined based on the discretion of responsible radiation oncologists: CES-applied in 41 patients; and CES-unapplied in 118. CES-applied patients experienced pain events less frequently (pain-killer usage: 53.7 % vs. 77.1 %, p = 0.008) and less severely (AQA score of 2–3: 39.0 % vs. 68.6 %, p = 0.002). On multivariate analyses, overlapping volume of esophagus and planning target (HR = 1.32, 95 % CI 1.12–1.55, p = 0.001) and CES-IMRT application (HR = 0.31, 95 % CI 0.13–0.76, p = 0.010) were associated with AQA score of 2–3 less frequently. There were no differences in failure pattern, progression-free survival, and overall survival. ConclusionsCES-IMRT application resulted in less frequent and less severe pain events without compromising oncologic outcomes. Further studies, preferably in a randomized fashion, would be desired.

Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy Reduces the Bone Mineral Density Loss of Patients With Cervical Cancer

PurposeTo test the efficacy and feasibility of pelvic bone marrow sparing intensity modulated radiotherapy (PBMS-IMRT) in reducing bone density loss for patients with cervical cancer undergoing pelvic radiotherapy (RT). Methods and MaterialsNon-surgical cervical cancer patients with Stage Ib2–IIIc cancer were randomly allocated into the PBMS group or the control group. The PBMS group additionally received PBM dose constraint. Computed tomography (CT) imaging sets were acquired at baseline and at 1, 3, 6, 9, and 12 months after treatment. Radiation dose and Hounsfield unit (HU) were registered. Bone density loss rates and fracture events at different follow-up time points were recorded. ResultsData from 90 patients in the PBMS group and 86 patients in the control group were used for statistical analysis, which included 30 and 26 patients with extended-field RT (EFR), respectively. The median follow-up for all patients was 12 months. Compared to baseline, the bone density of all bones at the last follow-up had decreased by 43% and 53% in the PBMS and control groups, respectively, with the most significant decline at 1 month after treatment. Although patients without extended-field radiation received minimal irradiation in the upper lumbar spine, a 22.33% decrease in bone density was detected. In the group of patients with EFR, the decrease was 51.18% (P < 0.01). Lumbar or pelvic fracture incidence rates of patients in the PBMS and control groups were 7.8% and 12.79%, respectively. Among the dosimetric parameters, mean dose had the strongest correlation with bone density loss. ConclusionIn patients undergoing pelvic RT, the loss of bone density can begin to appear early after RT, and it can occur either inside or outside of the irradiation field. Results of this study showed that PBMS-IMRT reduced bone mineral density loss compared with IMRT alone.

Effect of bilateral superficial parotid gland sparing IMRT on xerostomia and QOL: A prospective study

ABSTRACT Background: Superficial lobe constitutes 80% of the parotid and is situated lateral to mandible and can be better spared during intensity modulated radiation therapy (IMRT) for head and neck cancer (HNC). This study aimed to see the impact of bilateral superficial parotid gland (PG) sparing IMRT on xerostomia and quality of life (QOL) in patients with HNC receiving radiation. Study Design: Prospective, questionnaire-based study. Materials and Methods: Thirty-four patients with histopathologically proven non-nasopharyngeal non-oral cavity HNC were included in this study. IMRT technique was used and a constraint of 24 Gy was given to combined superficial PG. Physician- and patient-rated xerostomia and QOL scores were recorded at baseline and two weeks, three months, and six months post-radiation therapy (RT). The combined superficial PG dose correlated with xerostomia and QOL scores. Results: The combined superficial PG and combined whole PG mean dose was 18.71 Gy and 30 Gy, respectively, and the difference was statistically significant (P-&lt; 0.001). At two weeks, three months, and six months post-RT, the odds of xerostomia scores were 0.11, 0.071, 0.042, respectively for a median dose of &lt;18 Gy compared to &gt;18 Gy and was statistically significant P=(0.001). Conclusion: Bilateral superficial PG sparing IMRT is beneficial in reducing xerostomia and translates to a better QOL.

The Feasibility of Level Ib Sparing Intensity Modulated Radiation Therapy in Nasopharyngeal Carcinoma Patients with High-Risk Factors: Based on International Guideline

In spite of the rarity of level Ib recurrence after intensity-modulated radiation therapy, the International Guideline (IG) provides the risk factors for prophylactic coverage. In practice, however, there are significant differences between institutions. The purpose of this study is to examine the feasibility of sparing level Ib IMRT in NPC patients with high-risk factors based on IG. From January 2014 to October 2017, newly-diagnostic, non-metastatic NPC patients in our center were retrospectively reviewed. According to the risk factors of prophylactic level Ib coverage in patients with negative level Ib recommended by IG, the characteristics of pre-treatment MRI were analyzed. Four high-risk factors were identified: a. involvement of the structures that drain to level Ib as first echelon (FES), including anterior half of nasal cavity, oral cavity, b. involvement of submandibular gland (SMG), c. with radiologic extranodal extension (rENE) in level II LNs, or d. maximal axial diameter (MAD)≧2 cm in level II LNs. Patients with risk factors were divided into Cohort A (with risk factors a), Cohort B (with risk factor b, but without a), and Cohort C (only with risk factors c and/or d). Recurrence rates of level Ib and regional relapse-free survival (RRFS) rates were evaluated in different cohorts. A total of 961 patients were finally included. Thirty-six cases (3.7%) presented with radiologically positive level Ib metastasis. For the other patients with negative Ib LNs, there were 18, 65, 421, and 444 cases classified as FES involvement, SMG involvement, level II LNs with rENE, and level II nodal with MAD ≧2 cm. Excluding overlap, a total of 571 patients with risk factors were divided into three groups: Cohort A (n = 18), Cohort B (n = 49) and Cohort C (n = 504). Nine patients (9/961, 0.94%) developed level Ib recurrence. Except for 1 patient with positive Ib LNs at diagnosis, 2 did not meet any of the risk factors, while the other six (6/9, 66.7%) met at least one risk factor. The rate of recurrence at neck level Ib was highest in Cohort A (11.1%, 2/18; Ib-sparing group: 0/10, 0.0% vs Ib-covering group: 2/8, 25.0%; P = 0.183). In Cohort B, no cases were found with level Ib recurrence (0.0%, 0/49). In Cohort C, the rates were rare (0.8%, 4/504) in both groups (0.7%, 2/276 vs 0.9%, 2/228; P > 0.999). Among the three Cohorts, there were no significant differences in 5-year RRFS between two groups, which were 90.0% vs 62.5% (p = 0.248), 90.9% vs 92.0% (p = 0.905), and 92.6% vs 90.1% (p = 0.445), respectively. Among patients with high-risk factors, the incidence of grade 3-4 late dry mouth symptom was higher in the level Ib-covering group (3.1% vs 7.5%, P = 0.033). Level Ib sparing appears safe and feasible for NPC patients with negative level Ib LNs, even if combined with risk factors: SMG involvement, and/or level II with rENE, and/or level II MAD ≧2 cm. Level Ib-sparing irradiation reduces dry mouth symptoms compared with level Ib-irradiation.

Comparison of CT and MRI for contouring active bone marrow in bone marrow sparing IMRT of carcinoma cervix and its effects on functional outcomes

ObjectiveIntensity-modulated radiotherapy (IMRT) has been used to reduce dose to bone marrow (BM) irradiation during pelvic conformal radiotherapy by contouring bone marrow and sparing it during radiotherapy planning. The present study was done to compare CT & MRI for contouring bone marrow to spare functional bone marrow for Intensity-modulated radiotherapy (IMRT) in carcinoma cervix and to assess its effect on functional outcome. Material & methodsThis prospective, observational study included newly diagnosed carcinoma cervix patients treated by radical chemoradiation. Patients were distributed in two arms i.e. CT arm and MRI for contouring bone marrow. Regions taken into consideration for bone marrow volumes contouring were 4th and 5th Lumbar vertebrae, whole pelvis and proximal femur upto lesser trochanter. In CT arm bone marrow regions were contoured using freehand method with window adjusted to bone range (Window – 2500/ Level – 400) and in MRI arm BM regions on the MR images that had pixel values similar to muscle or IDEAL IQ sequence based on fat fractions present in bone marrow (BM) was used to contour. Results17 patients in CT arm and 19 patients in MRI arm were included. There was no significant difference between the groups in terms of Bone Marrow Volume (cm3) (W = 171.500, p = 0.763). The mean value of V10, V20, V30 and V40 all were lower in group II (MRI) but the differences in volume were not significant. Bone marrow V30 in CT arm was found to correlate with absolute neutrophil count drop which was statistically significant in univariate (Coefficient – 1.00 [0.14–2.01, p = 0.025] and multivariate analysis (Coefficient – [1.08 (0.14 to 2.01, p = 0.025]). Bone marrow V30 in MRI arm was found to correlate with total leucocyte count percentage drop, which on multivariate analysis was statistically significant (Coefficient – 1.29 [0.29–2.28, p = 0.013]). ConclusionsDosimetric parameters of bone marrow V10 and V30 were found to be associated with absolute neutrophil and total leucocyte nadir respectively. Haematological toxicity was observed more in MRI arm but more propspective studies are required for further validation.

Regional Recurrence after Carotid Sparing IMRT for Early Stage Glottic Cancer

An 82-year-old man with a 100-pack-a-year smoking history developed hoarseness. His initial videostroboscopy demonstrated an exophytic mass on the right middle to posterior true vocal cord, ulceration of the anterior true vocal cord, anterior commissure involvement, and normal vocal cord mobility (Fig. 1). The biopsy of the vocal cord mass demonstrated invasive squamous cell carcinoma (SCC). The staging neck computed tomography (CT) scan was negative for paraglottic fat space invasion and lymphadenopathy. The cancer was staged as clinical cT1 cN0 cM0, stage I. He completed definitive radiation 63 Gy in 28 fractions using carotid-sparing intensity modulated radiation therapy (IMRT) (Fig. 2A).

Impact on xerostomia for patients with nasopharyngeal carcinoma treated with superficial parotid lobe-sparing intensity-modulated radiation therapy (SPLS-IMRT): A prospective phase II randomized controlled study.

6059 Background: In the intensity-modulated radiation therapy (IMRT) era, xerostomia remains one of the most common radiation-induced toxicities in nasopharyngeal carcinoma (NPC) patients. We first proposed the superficial parotid lobe–sparing IMRT (SPLS-IMRT) technique in NPC, which has been proved to significantly reduce the mean doses of bilateral entire parotid glands and superficial parotid lobes. To further validate its clinical benefits, we conducted a prospective phase II randomized controlled study to compare the incidence of xerostomia in NPC patients treated with SPLS-IMRT and conventional IMRT (C-IMRT). Methods: Patients with histologically confirmed NPC who met the eligibility criteria were randomly assigned in a 1:1 ratio to receive either SPLS-IMRT or C-IMRT. The V36 (the percentage volume receiving a dose of 36 Gy) of the entire parotid gland was constrained to be less than 40% in both groups. Additionally, V26 (the percentage volume receiving a dose of 26 Gy) of the superficial parotid lobe was constrained to be less than 30% in the SPLS-IMRT group. The primary endpoint was the incidence of xerostomia at 12 months post-IMRT. The secondary endpoints included the xerostomia questionnaire (XQ) score, unstimulated salivary flow rate (USFR), stimulated salivary flow rate (SSFR), and survival outcomes. Results: From January 2018 to September 2018, 90 patients were enrolled (45 per group). Eighty-two patients were included for xerostomia analysis (42 in the SPLS-IMRT group and 40 in the C-IMRT group). At 12 months post-IMRT, the incidence of xerostomia in the SPLS-IMRT group was significantly lower than that in the C-IMRT group (83.4% vs. 95.0%; P = 0.007), especially the grade 3 xerostomia (0% vs. 12.5%; P &lt; 0.001). However, the median change in XQ score (XQchange) was similar between the two groups (11.9 points vs. 14.1 points; P = 0.194). Moreover, there was a significantly higher median fractional USFR (0.67 vs. 0.35; P = 0.024) and SSFR (0.66 vs. 0.32; P = 0.021) in the SPLS-IMRT group than the C-IMRT group. All 90 patients were included for survival analysis. With a median follow-up time of 37.8 months (IQR, 33.9–38.5 months), the 3-year locoregional relapse-free survival, distant metastasis-free survival, and overall survival in the SPLS-IMRT and C-IMRT groups were 92.5% vs. 90.9% (hazard ratio [HR], 1.84; P = 0.477), 83.8% vs. 81.7% (HR, 1.13; P = 0.816), and 88.9% vs. 88.2% (HR, 0.96; P = 0.949), respectively. Conclusions: SPLS-IMRT significantly reduced the incidence of xerostomia at 12 months post-IMRT in NPC by recovering parotid gland function earlier than C-IMRT, without compromising survivals. Phase III clinical trials are needed to confirm this result. Clinical trial information: NCT05020067.

Outcomes of carotid sparing intensity-modulated radiotherapy for early stage glottic cancer in 201 patients: Multicenter study of Turkish Radiation Oncology Society/TROD-01-007.

To assess and report clinical outcomes after carotid sparing intensity-modulated radiotherapy for early stage laryngeal cancer. We retrospectively analyzed 201 patients with early stage glottic laryngeal cancer treated with carotid sparing intensity-modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) techniques in six TROD centers. After a median follow-up of 31 months the actuarial 1- and 3-year local and locoregional control rates were 99.4% and 94.7%, 98.4% and 93%, respectively. T classification, anterior commissure involvement, IMRT technique, and type of fractionation were not found to be prognostic for local control. Overall, eight patients had lost their organ function due to recurrence or toxicity. Grade 3 and 4 acute laryngeal edema was seen in eight (4%) and one (0.5%) of patients, respectively. Grade 3 and 4 late laryngeal edema developed in two (1%) and one patient (0.5%), respectively. Oncologic outcomes of patients treated with carotid sparing IMRT were excellent; comparable with historical series, with acceptable side effects. Longer follow-up is needed to estimate long term effect on stroke.

Abstract P1-21-02: Scalp sparing whole-brain radiotherapy using IMRT technique. Do we need it?

Abstract Introduction: The prognosis of metastatic breast cancer patients is improving due to advances in systemic therapy, which led to better control of the disease. Brain metastasis that requires whole-brain radiotherapy (WBRT) is mandatory for some patients.Acute alopecia is a common side effect, and total hair loss occurs in 100% of patients receiving parallel opposed direct laterals fields.Because of the recognized reduction in quality of life associated with clinically apparent and clinically undetectable hair loss, efforts are made to minimize hair loss resulting from WBRT.It is theorized that intensity-modulated radiotherapy (IMRT) may reduce hair loss. It will be less patchy because IMRT enables dose modulation, minimizing the radiation dose received by the hair follicles in the scalp.This dosimetric study assessed the dose received to the whole scalp and its subvolumes by three radiotherapy techniques. Methods: A total of 30 treatment plans for ten patients receiving WBRT were evaluated retrospectively. All patients were simulated in a supine position with a thermoplastic mask. The scalp was contoured as 5 mm between the skin and the outer table of the skull. Then we subdivided the scalp volume into superior, anterior, lateral, and posterior subvolumes. The dose prescribed was 30 Gy in 10 fractions. We compared three different radiotherapy techniques using the standard WBRT procedure that involves applying two lateral opposing fields (OF-WBRT) with a margin surrounding the brain, which includes the hair follicles situated about 5 mm. below the scalp, the field in field (FiF), and IMRT techniques without introducing the scalp in the optimization process using 6 MV photon energy. Results: All techniques showed comparable PTV coverage. The homogeneity index with opposed lateral was 0.057±.09, 0.057±.0111 for FiF, and 058±.0114 for IMRT with no statistically significant difference (p = 0.407).IMRT resulted in a marked decrease in all scalp parameters with a statistically significant difference, with a little difference in the dose delivered to lateral subvolumes. (table 1) Conclusion: Scalp sparing IMRT for WBRT reduces the scalp dose compared to conventional WBRT, especially in the superior, anterior and posterior axis. Further randomized prospective trials are needed to confirm this benefit. 2 Table. PTV coverage and dose to the scalp and its subvolumes.characteristicsOPPOSED LATERALFIFIMRTP-ValueMean ± SDMean ± SDMean ± SDAll groupsOpposes lateral/FIFOpposes lateral/IMRTIMRT/FIFPTV D 98%96.9±0.796.9±0.797.1±0.71.000Scalp mean dose (cGy)2165.7±270.52120.5±242.81385.9±306.7&amp;lt;0.0010.076&amp;lt;0.0010.076Scalp V 20 (%)68.4±12.567.1±11.237.6±11.2&amp;lt;0.0010.221&amp;lt;0.0010.042Superior mean dose (cGy)2396.8±138.92326.1±1211419.0± 372.4&amp;lt;0.0010.076&amp;lt;0.0010.076Anterior mean dose (cGy)2180.9±237.82209.7±205.01267.4±462.2&amp;lt;0.0010.221&amp;lt;0.0010.042Lateral mean dose (cGy)2127.7±252.62136.9±249.12071.4±257.10.0020.2210.2210.001Posterior meanDose (cGy)2317.8±205.62273.3±207.81467.2±209.7&amp;lt;0.0010.0760.076&amp;lt;0.001 Citation Format: Mohsen Samy Barsoum, Emad Mohsen Barsoum, Maha Kamaleldin, Niven Mahmoud, Shaimaa Abdelgeleel, May Gamal Ashour. Scalp sparing whole-brain radiotherapy using IMRT technique. Do we need it? [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-21-02.

English

BACKGROUND The primary objective of this study is a dosimetric comparison for the feasibility of carotid sparing intensity modulated radiation therapy (CS-IMRT) for early glottis cancer. The planning target volume coverage and the spinal cord dose are compared in the 3-dimensional conformal radiotherapy (3DCRT) and IMRT plans. METHODS In this single reconcile study twenty-five patients who had been already treated for early-stage glottis cancer (T1, T2N0M0) from June 2015 to June 2021 with 52.5 Gy/15 fractions were included. All patients were simulated in supine position with an orfit shell and treatment planning computed tomography scans were obtained from the vertex to sternal angle with a 3-mm slice thickness. Treatment was executed with 3-DCRT plan and comparison was made with the newly created IMRT plan. The analysis was made regarding mean dose to the carotid arteries, volume of carotid artery receiving more than 25 Gy (V25), 35 Gy (V35), 50 Gy (V50), planning target coverage and doses to organ at risk. RESULTS The dose to carotids was significantly higher in the 3-DCRT plan compared with the IMRT plan (p=0.004). For target coverage the volume receiving 95% of the dose was significantly higher in IMRT plan (p=.001). The dose to the spinal cord was higher-in the IMRT plan (p=.001) compared to 3-DCRT plan. CONCLUSIONS IMRT maintains target volume coverage with significant reduction in carotid artery dose. This reduces the incidence of cerebrovascular accidents by decreasing the radiation induced carotid artery stenosis, thereby improving the quality of life of patients. KEY WORDS CS-IMRT, 3D-CRT, Mean Carotid Dose

Swallowing sparing intensity modulated radiotherapy versus standard parotid sparing intensity-modulated radiotherapy for treatment of head and neck cancer: a randomized clinical trial

Background Dysphagia is a distressing symptom during and after radiotherapy treatment in head and neck cancer (HNC) patients. The objective of this prospective study was to investigate whether swallowing sparing intensity modulated radiotherapy (SW-IMRT) reduces the occurrence of swallowing dysfunction compared to the standard IMRT (ST-IMRT). Methods We randomized, planned, and treated patients with HNC who needed whole neck irradiation using the simultaneous integrated boost (SIB) IMRT technique. Doses of 70, 60, and 54 Gy (over 33 daily fractions) were prescribed to the primary tumor, high-risk and low-risk regions, respectively. The postoperative cases received 60 and 54 Gy (over 30 daily fractions) to the high-risk planning target volume (PTV) and low-risk PTV. We contoured organs at risk related to swallowing dysfunction (SWOARs) in all cases. In the ST-IMRT group, parotids only were spared. In the SW-IMRT group, parotids and SWOARs outside the high-risk PTV were spared. Assessment of dysphagia included clinical and instrumental evaluation. Results One hundred forty-six patients ended their radiotherapy treatment. Dose distribution showed comparable PTV coverage and no difference in parotid glands sparing between the two groups. SWOARs dose reduction with SW-IMRT differs according to tumor location and its overlap with SWOARs. Using different assessment methods, SW-IMRT was associated with a lower occurrence of dysphagia up to one year after treatment. There was no difference between the two groups regarding acute dysphagia (p = 0.262), overall survival (p = 0.811), and disease-free survival (p = 0.876). Conclusion SW-IMRT is significantly better than ST-IMRT regarding a physician-rated and objective assessment of swallowing dysfunction at short- and long-term post-treatment follow-up.

Comparison of Recurrence With High Retropharyngeal Nodal-Sparing Intensity-Modulated Radiation Therapy in HPV-Related and HPV-Unrelated Oropharyngeal Cancer

Patients with HPV-related oropharyngeal cancers (HPV+OPC) are known to have a superior locoregional control when compared to HPV-unrelated oropharyngeal cancers (HPV-OPC). The introduction of intensity-modulated radiation therapy (IMRT) has allowed dose painting and sparing of bilateral uninvolved high retropharyngeal nodes (RP). We reviewed outcomes and patterns of recurrence in patients with oropharyngeal cancer (OPC) treated with IMRT in patients with HPV+OPC and those with HPV-OPC. We hypothesize that high-RP sparing RT can reduce morbidity in HPV+OPC without sacrificing disease control.We retrospectively reviewed all adults with OPCs treated with curative intent IMRT ± chemotherapy from 2012-2017 at a single institution. HPV status was tested by p16 staining for all OPCs and patients were staged per the TNM 8th edition. All patients were treated with high-RP sparing, meaning omission of the nodal basin from the caudal limit of C2 to the base of skull bilaterally. Patients who did not complete prescribed treatments, with multiple primaries or with less than 3 months of follow up were excluded. Patients, disease, treatment and outcome data were retrieved. Date and location of local, regional, retropharyngeal and distant recurrences were recorded. Time to events, including RP recurrence-free survival (RP-RFS), regional recurrence-free survival (R-RFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and log-rank test were performed, for HPV+OPC vs HPV-OPC.The final analysis included 240 patients. Median follow-up was 4.18 years (0.25- 8.46). HPV+OPC patients accounted for 81% while HPV-OPC 19%. Median age was of 60 years (40 - 94.6) and 85.2% of patients were male. The most common primary subsites were tonsil (66.5%), and base of tongue (32.8%). Patients had stage I disease in 43%, stage II in 29%, stage III in 18% and stage IV in 10%; 84.6% of patients had nodal disease. Concurrent systemic treatments were delivered in 74% of patients. Overall, there were 3 patients (1.5%) with RP recurrences in HPV+OPC vs 2 patients (4.4%) in HPV-OPC. The 2-year RP and 5-year RP-RFS was 98% for HPV+OPC and 94% for HPV-OPC (P = 0.169). The 2-year and 5-year R-RFS was 92%/89% for HPV+OPC vs 80%/74% for HPV-OPC (P = 0.015) and 2-year and 5-year overall survival was 92%/78% for HPV+OPC vs 81%/59% for HPV-OPC (P = 0.009).High-RP sparing IMRT technique is associated with less than 5% of isolated recurrence in the high RP nodal region, despite most patients presenting with involved nodal disease. Our data showed no statistically significantly difference in the HPV+OPC vs HPV-OPC patients. As a result, these data suggest that continuing this practice is associated reasonable disease control and further studies are needed to evaluate patients' long-term quality of life and morbidity.

Effect of Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy on Acute Hematologic Toxicity in Rectal Cancer Patients Undergoing Chemo-Radiotherapy.

BackgroundWhile chemo-radiotherapy improves local control in patients with locally advanced rectal cancer, it can also increase acute hematological toxicity (HT), which leads to poor outcomes. Patients receiving bone marrow radiation have been shown to develop acute HT. However, the safety and efficacy of bone marrow sparing is undetermined. The aim of our study was to explore the feasible dosimetric constraints for pelvic bone marrow (PBM) that can be widely used in rectal cancer patients undergoing chemo-radiotherapy.Methods112 rectal cancer patients were selected and divided into the PBM sparing IMRT group (60 cases) and the non-PBM sparing IMRT group (52 cases). All patients underwent pelvic radiotherapy with concurrent capecitabine-based chemotherapy. The PBM dosimetric constraints in the PBM sparing IMRT group were set to:V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%. An independent sample t test was applied for the dose-volume parameters, and Chi-squared analysis was applied for clinical parameters and adverse events.ResultsThe radiation dose to PBM (V5~V45, Dmean, P<0.05), PBM sub-regions (V10~V35, Dmean, P<0.05) and both femoral heads (V5~V40, Dmean, P<0.05) decreased significantly in the PBM sparing IMRT group compared with that of the non-PBM sparing IMRT group (P<0.05). There was no significant difference in any dose-volume parameters of the bladder and small bowel in either groups, and none in the planning target volume (PTV) dose homogeneity and conformity (P>0.05). For acute HT observation, the incidence of grade 3 acute HT (χ2 = 7.094, P=0.008) was significantly reduced in patients treated with PBM sparing IMRT compared with patients treated with non-PBM sparing IMRT. There was no statistical difference in the incidence of vomiting, diarrhea, fatigue, anorexia, nausea, hand-foot syndrome, cystitis, perianal pain and perianal dermatitis in patients of both groups (P >0.05).ConclusionsApplying PBM dosimetric constraints (V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%) can significantly reduce the radiation dose to PBM. The patients treated with PBM sparing IMRT had a lower incidence of acute HT compared with those treated with non-PBM sparing IMRT. Applying the PBM dosimetric constraints proposed by our study can benefits the patients with rectal cancer undergoing capecitabine-based chemo-radiotherapy.

Parotid sparing and quality of life in long-term survivors of locally advanced head and neck cancer after intensity-modulated radiation therapy.

Intensity-modulated radiation therapy (IMRT) enables radiation oncologists to optimally spare organs at risk while achieving homogeneous dose distribution in the target volume. Despite great advances in technology, xerostomia is one of the most detrimental long-term side effects after multimodal therapy in patients with locally advanced head and neck cancer (HNC). This prospective observational study examines the effect of parotid sparing on quality of life in long-term survivors. A total of 138patients were grouped into unilateral (n = 75) and bilateral (n = 63) parotid sparing IMRT and questioned at 3, 24, and 60-month follow-up using the European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-H&N35 questionnaires. Treatment-related toxicity was scored according to the RTOG/EORTC toxicity criteria. Patients' QoL24 and 60months after IMRT was analyzed by ANCOVA using baseline QoL (3months after IMRT) as acovariate. Patients with bilateral and unilateral parotid-sparing IMRT surviving 60months experience similar acute and late side effects and similar changes in QoL. Three months after IMRT, physical and emotional function as well as fatigue, nausea and vomiting, pain, dyspnea, and financial problems are below (function scales) or above (symptom scales) the threshold of clinical importance. In both groups, symptom burden (EORTC H&N35) is high independent of parotid sparing 3months after IMRT and decreases over time in asimilar pattern. Pain and financial function remain burdensome throughout. Long-term HNC survivors show asimilar treatment-related toxicity profile independent of unilateral vs. bilateral parotid-sparing IMRT. Sparing one or both parotids had no effect on global QoL nor on the magnitude of changes in function and symptom scales over the observation period of 60months. The financial impact of the disease and its detrimental effect on long-term QoL pose an additional risk to unmet needs in this special patient population. These results suggest that long-term survivors need and most likely will benefit from early medical intervention and support within survivorship programs.

Intensity modulated radiation therapy and oral mucosa sparing in Head and neck cancer patients: A systematic review on behalf of Italian Association of Radiation Oncology - Head and neck working group.

Oral mucositis is a common dose-limiting toxicity during radiotherapy with or without chemotherapy in head and neck cancer patients. This potentially severe complication globally worsens quality of life and negatively impacts local control and survival's outcomes. Several studies have been published on feasibility and/or clinical benefit of intensity modulated radiotherapy (IMRT) mucosa-sparing technique. In 2017, the Italian Association of Radiation Oncology Head and Neck Cancer Working Group organized a study group to perform a systematic review. The aim was to verify if practical indications, including dose-constraints and demonstrated clinical benefit, could be proposed for oral mucosa (OM)-sparing IMRT in order to reduce the incidence of severe acute mucositis. Although dose to OM should be reduced as much as possible without compromising target volumes coverage, it is still tricky to firmly state that OM-sparing procedure should be considered the standard of care, especially due to high subjective variability in OM contour.

387P - Radiation dose to contralateral parotid during treatment of carcinoma buccal mucosa

Background: To compare the contralateral parotid gland dose during radiation treatment of carcinoma buccal mucosa with 3 Dimensional Conformal Radiotherapy (3D-CRT) vs. Parotid sparing Intensity Modulated Radiotherapy (IMRT). Methods: Ten consecutive lateralized carcinoma of the oral cavity patients treated with a prospective management using ipsilateral irradiation were studied. This included 4 radical and 6 postoperative oral cavity carcinomas, with Stage T1-T2, N0-N2b disease. Five patients were treated with 3D-CRT and five with IMRT. The dose received by contralateral parotid gland was assessed by volumetric analysis. Results: Dose-volume histograms (DVH) showed the mean dose to contralateral parotid was 896.6 cGy (range: 0.5-10 Gy) with 3D-CRT and 503.8cGy (range: 0.4-4 Gy) with IMRT. With IMRT 97%-105% of the prescribed dose was received by 95% of the target volumes. Mean dose to the PTV Primary site was 67.8 Gy (range, 65-71 Gy) for primary RT and 60.5 Gy (range: 55-66 Gy) for post-operative RT. The mean dose to the PTV Node (ipsilateral lymph nodes) was 50.8 Gy (range: 49-53 Gy). Conclusions: There is a considerable increase in the mean dose of contralateral parotid in 3DCRT compared to IMRT. Parotid sparing IMRT helps reducing the radiation dose received by salivary glands. Legal entity responsible for the study: CBCC-Chennai, Saveetha University, Chennai. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.

Pattern of dysphagia after swallowing-sparing intensity-modulated radiotherapy (IMRT) of head and neck cancers: results of amono-institutional prospective study.

Aprospective instrumental assessment of late dysphagia using swallowing organs at risk (SWOARs)-sparing IMRT for nasopharyngeal and oropharyngeal cancers. Objective instrumental assessment included fiberoptic endoscopic evaluation of swallowing (FEES) and videofluoroscopy (VFS) at baseline, and at 6 and 12months after treatment. FEES assessed the pharyngeal residue according to the Farneti pooling score (P-score) as follows: 4-5 no dysphagia; 6-7 mild dysphagia; 8-9moderate dysphagia; 10-11severe dysphagia. Three different consistencies were tested for the P‑score: liquid (L), semisolid (SS), and solid (S). VFS assessed penetration-aspiration according to the Penetration-Aspiration Scale (PAS) and two different consistencies of the bolus were tested: thin liquid barium (L) and paste barium (S). 38patients were evaluable. There was asignificant worsening of the P‑score at 6months both for SS (p = 0.015) and S (p < 0.001), which persisted only for S at 12months (p < 0.0001). Similarly, there was asignificant worsening of the PAS score at 6 and 12months (p = 0.065 and 0.039, respectively) for the Sbolus. Overall, 3-7 and 10-14% aspiration after L and S was observed, respectively. Promising results using aSWOARs-sparing IMRT technique are reported. Therefore, treatment plans should be optimized for reducing doses to these structures.

Prospective Validation of Bone Marrow Constraints for Hematological Toxicity in Patients Undergoing Chemoradiation for Cervical Cancer

Dose volume constraints (DVCs) have been proposed for reducing hematological toxicity (HT) in patients undergoing chemo radiation (CRT). The present study was undertaken to investigate validity of the DVCs during three-dimensional conformal radiation (3DCRT) or intensity modulated radiotherapy (IMRT) for cervical cancer. Clinical database of patients receiving bowel sparing adjuvant IMRT or 3DCRT with weekly concurrent cisplatin (40 mg/m2) within context of an ongoing trial was reviewed. No prospective BM sparing was performed. RT planning scans were de-archived and BM was contoured using Whole Bone (WB) and free hand inner cavity (FH) technique. Segmentation into sub-regions namely whole pelvic lumbar, lumbosacral spine, sacrum, ilium, ischium, femoral head and neck, whole pelvis and lower pelvis was performed. WB and FH BM subvolumes receiving 10, 20, 30, 40 Gy were determined. Receiver operator characteristics analysis was performed to identify DVCs that predict for grade ≥ II HT. All data was dichotomized across these DVCs for univariate and multivariate analysis. Finally an independent sample t test was performed to identify treatment technique that best spares the BM sub-regions that predict for HT. Overall 128 patients (IMRT=73; 3DCRT=55) that received CRT were included. Grade ≥ II HT and ≥ III HT was observed in 33.3% and 4.3% respectively. Grade ≥ II anemia, leucopenia, neutropenia and thrombocytopenia was observed in 14.3%, 21.9%, 5% and 0.7% patients respectively. On univariate analysis none of the known predictive factors (V10 or V40) predicted for overall Grade ≥ II HT. However Grade ≥ II neutropenia was predicted by Whole pelvic lumbar V20 >75% (WB and FH, p< 0.04,0.02) and V40 FH>35% (p<0.02), Whole pelvic V10 WB>90% (p<0.03), Whole Pelvic FH V20>75% (p<0.03) and lower pelvis FH >55% (p<0.04) and femoral head and neck FH V10> 80% and V20>35% (p< 0.03 and 0.02 respectively). On multivariate analysis, whole pelvic lumbar FH V40 >35%, whole pelvic WB V10>90%, femoral head and neck V 20 >35% predicted for Grade ≥ II neutropenia. Of the identified DVCs, V40 and V20 are better spared with IMRT (p<0.0001) whereas V10 is better spared by 3DCRT (p<0.0001) BM sub-volume doses predict for Grade ≥ II neutropenia in patients receiving CRT. As both high dose and low dose regions are important, the planning aim for BM sparing IMRT should be defined accordingly in prospective studies.

Feasibility of atlas-based active bone marrow sparing intensity modulated radiation therapy for cervical cancer

BackgroundTo test the hypothesis that atlas-based active bone marrow (ABM)-sparing intensity modulated radiation therapy (IMRT) yields similar dosimetric results compared to custom ABM-sparing IMRT for cervical cancer patients. MethodsWe sampled 62 cervical cancer patients with pre-treatment FDG-PET/CT in training (n=32) or test (n=30) sets. ABM was defined as the subvolume of the pelvic bone marrow (PBM) with standardized uptake value (SUV) above the mean on the average FDG-PET image (ABMAtlas) vs. the individual’s PET (ABMCustom). Both were deformed to the planning CT. Overlap between the two subvolumes was measured using the Dice coefficient. Three IMRT plans designed to spare PBM, ABMAtlas, or ABMCustom were compared for 30 test patients. Dosimetric parameters were used to evaluate plan quality. ResultsABMAtlas and ABMCustom volumes were not significantly different (p=0.90), with a mean Dice coefficient of 0.75, indicating good agreement. Compared to IMRT plans designed to spare PBM and ABMCustom, ABMAtlas-sparing IMRT plans achieved excellent target coverage and normal tissue sparing, without reducing dose to ABMCustom (mean ABMCustom dose 29.4Gy vs. 27.1Gyvs. 26.9Gy, respectively; p=0.10); however, PTV coverage and bowel sparing were slightly reduced. ConclusionsAtlas-based ABM sparing IMRT is clinically feasible and may obviate the need for customized ABM-sparing as a strategy to reduce hematologic toxicity.