Partial Breast Irradiation Research Articles

PL05 Presentation Time: 2:30 PM: Long-Term Late Side-Effects after Breast Conserving Surgery and Whole Breast Irradiation versus Accelerated Partial Breast Irradiation Using Multicatheter Brachytherapy - 10-Year Update of the GEC-ESTRO Multicentric Phase 3 Trial

PL05 Presentation Time: 2:30 PM: Long-Term Late Side-Effects after Breast Conserving Surgery and Whole Breast Irradiation versus Accelerated Partial Breast Irradiation Using Multicatheter Brachytherapy - 10-Year Update of the GEC-ESTRO Multicentric Phase 3 Trial

BP06 Presentation Time: 4:45 PM: Dosimetric Evaluation of Accelerated Partial Breast Irradiation (APBI) with the TRIUMPH-T Trial Regimen Using SAVI Applicator—Single Institution Retrospective Analysis

BP06 Presentation Time: 4:45 PM: Dosimetric Evaluation of Accelerated Partial Breast Irradiation (APBI) with the TRIUMPH-T Trial Regimen Using SAVI Applicator—Single Institution Retrospective Analysis

BP09 Presentation Time: 5:12 PM: Doubly Accelerated Partial Breast Irradiation after Breast-Conserving Surgery: High Five (HiFi) APBI Study - Preliminary Report on Patients Quality of Life

BP09 Presentation Time: 5:12 PM: Doubly Accelerated Partial Breast Irradiation after Breast-Conserving Surgery: High Five (HiFi) APBI Study - Preliminary Report on Patients Quality of Life

BP10 Presentation Time: 5:21 PM: Perioperative Accelerated Partial Breast Irradiation Using the Multi-Catheter Technique - Ten Years of Experience at a Single Institution

BP10 Presentation Time: 5:21 PM: Perioperative Accelerated Partial Breast Irradiation Using the Multi-Catheter Technique - Ten Years of Experience at a Single Institution

BP03 Presentation Time: 4:18 PM: Seventeen-Year Single Institution Experience with Accelerated Partial Breast Irradiation Using Interstitial Multicathether Brachytherapy after Breast-Conserving Surgery for Low-Risk Invasive and In-Situ Carcinoma of the Female Breast

BP03 Presentation Time: 4:18 PM: Seventeen-Year Single Institution Experience with Accelerated Partial Breast Irradiation Using Interstitial Multicathether Brachytherapy after Breast-Conserving Surgery for Low-Risk Invasive and In-Situ Carcinoma of the Female Breast

BP07 Presentation Time: 4:54 PM: 2-year Follow-Up Results of Three-Fraction Accelerated Partial Breast Irradiation Using the SAVI Applicator with the Triumph-T Trial in Early-Stage Breast Cancer

BP07 Presentation Time: 4:54 PM: 2-year Follow-Up Results of Three-Fraction Accelerated Partial Breast Irradiation Using the SAVI Applicator with the Triumph-T Trial in Early-Stage Breast Cancer

Fat necrosis after accelerated partial breast irradiation or hypofractionated whole breast irradiation: A case-control study.

This study aimed to compare the incidence of fat necrosis after accelerated partial breast irradiation (APBI) vs hypofractionated whole breast irradiation (WBI) in patients with early-stage breast cancer. Data from early-stage breast cancer patients who underwent breast-conserving surgery and adjuvant radiotherapy between 2009 and 2022 were retrospectively collected. Radiation therapy consisted of APBI of 30 Gy in 5 daily fractions (Fx) (delivered in one week, consecutively) to the tumour bed or WBI (42.4 Gy in 16 Fx). Reports on fat necrosis were extracted from yearly mammograms and breast ultrasound imaging. The primary endpoint was the incidence of radiologically detected fat necrosis. A total of 536 patients were included among the APBI and WBI cohorts, with 268 and 268 patients respectively. The three-year Kaplan-Meier actuarial rate of fat necrosis was 32.8% (95% CI: 30.0% - 35.6%) for APBI and 22.3% (95% CI: 19.7% - 24.9%) for WBI patients. Univariate Kaplan-Meier survival analysis revealed a Hazard Ratio of 1.6 [95% CI: 1.1 - 2.2; p = 0.0055] for the fat necrosis rate within the APBI group compared to WBI. Multivariate Cox proportional hazard regression confirmed significant associations between fat necrosis and APBI (HR = 2.2 95% CI: 1.2 - 4.0; p = 0.01). The occurrence of radiologically diagnosed fat necrosis was higher in the APBI group compared to the WBI. Further investigations aiming to identify a lower-dose schedule with comparable efficacy to 30 Gy in 5 Fx but fewer toxicities, particularly for high-risk patients, are warranted.

Thursday, July 11, 20244:00 PM - 5:30 PM BP01 Presentation Time: 4:00 PM: Accelerated Partial Breast Irradiation Using Sole Interstitial Multicatheter Brachytherapy - GEC-ESTRO Phase 3 Trial: 10-year Results in Context of Current ASTRO and GEC-ESTRO Patient Selection Criteria

Thursday, July 11, 20244:00 PM - 5:30 PM BP01 Presentation Time: 4:00 PM: Accelerated Partial Breast Irradiation Using Sole Interstitial Multicatheter Brachytherapy - GEC-ESTRO Phase 3 Trial: 10-year Results in Context of Current ASTRO and GEC-ESTRO Patient Selection Criteria

BP08 Presentation Time: 5:03 PM: Doubly Accelerated Partial Breast Irradiation after Breast-Conserving Surgery - Early Toxicity and Early Cosmetic Results of High Five (HiFi) APBI Study

BP08 Presentation Time: 5:03 PM: Doubly Accelerated Partial Breast Irradiation after Breast-Conserving Surgery - Early Toxicity and Early Cosmetic Results of High Five (HiFi) APBI Study

Real world clinical outcomes from targeted intraoperative radiotherapy (TARGIT-IORT) during lumpectomy for breast cancer: data from a large cohort at a national cancer institute.

Randomised evidence supports the use of partial breast irradiation (PBI) with targeted intraoperative radiotherapy (TARGIT-IORT) for early stage breast cancer, but prospective data from real-world adoption of this technique is also important. The aim of this study was to determine if the outcome reported in TARGIT-A trial could be replicated in large cohort of early stage breast cancer treated with TARGIT-IORT. This prospective observational study analysed all patients treated with TARGIT-IORT between 2004 and 2021 in a single national cancer institute. TARGIT-IORT during lumpectomy was performed according to the risk-adapted TARGIT-A protocol using the Intrabeam® device. We analysed the completeness of follow up, 5-year in-breast-tumour-recurrence (IBTR), long term local recurrence free survival, distant disease-free survival, overall survival and breast-cancer-related survival, using the Kaplan-Meier method. A covariate analysis was performed to investigate risk factors for IBTR. We also analysed high grade toxicity events. The study included 814 patients and the a median follow up was 72 months. The majority of patients (60.3%) received TARGIT-IORT as PBI modality ("exclusive IORT" group); 39.7% received additional EBRT. There was no significant difference between the 5 years IBTR for the whole study population and the "exclusive IORT" cohort (1.6% (95%CI=1.1-2.1%) and 2.5% (95%CI=1.7%-3.3%) respectively). 5 years overall survival and tumour related survival were >95%. In 21% of patients with recurrence, breast was preserved. Radiotherapy toxicity (CTCAE Grade>2) was very rare (0.9%). This large single institute study found that breast cancer control and survival outcomes with TARGIT-IORT were consistent with TARGIT-A trial results. This "real world" experience confirmed that the randomised evidence showing the value of TARGIT-IORT as partial breast irradiation modality that can be replicated in routine clinical practice.

Technical feasibility of delivering a simultaneous integrated boost in partial breast irradiation

Feasibility of volumetric modulated arc therapy (VMAT) for partial breast irradiation (PBI) with simultaneous integrated boost (SIB) to tumour bed was investigated. Four plans were created for 10 patients: 30 Gy/5 fractions, 26 Gy/5 fractions with 30 Gy SIB, 40.05 Gy/15 fractions, and 40.05 Gy/15 fractions with 48 Gy SIB. SIB in the 5 fraction arm had reduced ipsilateral breast dose relative to uniform dose. SIB in the 15 fraction arm had noninferior conformity compared to uniform dose. Addition of SIB did not increase other organ-at-risk doses or plan complexity. VMAT PBI with SIB was feasible for both fractionation regimens.

Accelerated Partial Breast Irradiation for Early-Stage Invasive Lobular Carcinoma

Purpose: Invasive lobular carcinoma (ILC) represents 10-15% of invasive breast cancers with limited representation among trials of accelerated partial breast irradiation (APBI). Contemporary guidelines advise against treating ILC with APBI given a paucity of supportive evidence. Here, we evaluated oncologic outcomes among patients with ILC treated with APBI. Methods: Patients treated from 2010 –2022 with APBI following breast conserving surgery for ILC (or mixed ILC with other histologies) were ascertained from a prospectively-maintained institutional database. All patients received external beam APBI to 40Gy in 10 daily fractions. Outcomes of interest included local recurrence (LR) and overall survival (OS). Results: Of 1248 patients who underwent APBI at our center, the study cohort comprised 132 (11%) who had ILC, either exclusively or mixed with another histology (median age 63). Median tumor size was 1.1cm (IQR: 0.8, 1.5), nearly all had estrogen receptor positive disease (99%) and received endocrine therapy (91%), and most underwent sentinel node biopsy (89%) with the remainder having no axillary surgery. At 530 person-years and a median follow-up of 39 months, two LRs were observed yielding a 48-month cumulative incidence of LR of 3.0% (95% CI 0.56 –9.5%). Both events arose in patients with mixed lobular histology (none arose in patients with pure ILC). Two unrelated deaths were also observed yielding a 48-month overall survival of 98% (95% CI: 95% - 100%) Conclusion: Among patients with ILC who received APBI following BCS, we observed a 4-year LR rate of 3%. No regional or distant recurrences were observed, and overall survival was excellent. The safety of APBI for ILC will require confirmation among larger trials with longer follow-up, although the excellent outcomes observed here are consistent with those seen for invasive ductal carcinomas among contemporary trials of APBI.

324 - Initial clinical experience using a 6-dimensional (6D) positioning system with surface and thermal guidance for setup and intra-fraction motion management of partial-breast radiotherapy patients

324 - Initial clinical experience using a 6-dimensional (6D) positioning system with surface and thermal guidance for setup and intra-fraction motion management of partial-breast radiotherapy patients

A systematic review on the techniques, long-term outcomes, and complications of partial breast irradiation after breast-conserving surgery for early-stage breast cancer.

To evaluate the efficacy and safety of four techniques of partial breast irradiation (PBI) including interstitial brachytherapy (ISBT), balloon-based brachytherapy (BBT), Intraoperative radiotherapy (IORT) and three-dimensional conformal radiotherapy (3DCRT) in the treatment for early-stage breast cancer patients after breast-conserving surgery. A systematic search was performed according to the Preferred Reporting Items of Systematic Reviews and Meta-analyses (PRISMA) guidelines using the PubMed, Embase, Cochrane Library and Web of Science databases. The inclusion criteria were clinical trials and observational studies that reported on outcome measures of principal PBI techniques. The methodological quality of the included research data was assessed using bias risk assessment tool with the Methodological Index for Non-Randomized Studies (MINORS), and the research information were analyzed using data analysis software. Clinical studies were collected from the earliest available date until September 2023. Fifty-one studies were included, with a total sample size of 7708. The results of network meta-analysis (NMA) showed that ISBT can lower the local recurrence (SUCRA: 73.8%). In terms of reducing distant metastasis, 3DCRT may be the best choice (SUCRA: 52.5%). And IORT has the highest 5-year overall survival (SUCRA: 90%). Furthermore, ISBT also has the advantages of lowest risk with fat necrosis (SUCRA: 72.5%), infection (SUCRA: 78.3%) and breast pain (SUCRA: 86.2%). BBT may be the optimal solution for fibrosis (SUCRA: 76.9%) and hyperpigmentation (SUCRA: 66.7%). 3DCRT has lower incidence of telangiectasia (SUCRA: 56.7%) and better cosmetic result (SUCRA: 85%). Postoperative PBI treatment using ISBT after breast-conserving surgery in patients with early-stage breast cancer may be a more valuable choice based on the treatment efficacy and is associated with fewer late side-effects. Large-scale, prospective, long-term studies are warranted to clarify the role of different PBI techniques in selected patients.

Five-year results of the very accelerated partial breast irradiation VAPBI phase I-II GEC-ESTRO trial

Background and purposeThe standard partial breast postoperative treatment for early breast carcinomas with multi-catheter interstitial brachytherapy (MIBT) requires 7–8 fractions in 4–5 days as used in the APBI GEC-ESTRO phase III trial. In 2017 the GEC-ESTRO Breast Cancer Working Group started a Phase I-II trial to study if very accelerated partial breast irradiation (VAPBI) using 3–4 fractions could be equivalent. Material81 patients with low-risk invasive carcinomas underwent high dose rate MIBT. Mean age was 68 (51–90); 33 women received 4 fractions of 6.25 Gy in 2–3 days, and 48 subsequent patients 3 fractions of 7.45 Gy in 2 days, 36 perioperatively and 45 postoperatively. ResultsMedian follow-up was 62 months, with 5-year actuarial breast recurrence of 3.4 % (two cases). One patient died due to metastasis. Pigmentation changes in the entrance of tubes remained visible only in 12.3 % in long term (skin G1 toxicity). Fibrosis or slight induration (G1) in 22.2 % and G2 in 9.9 %. No case of telangiectasia has been described. Cosmetic outcome is good or excellent in 95 % and fair in 5 %. Four tumors located in the retroareolar area showed nipple retraction. ConclusionVAPBI with MIBT using four fractions of 6.25 Gy or three fractions of 7.45 Gy in two or three days offers good local control, with a 5-year rate of fibrosis G2 similar to the GEC ESTRO phase III trial. VAPBI in two days is a good choice to decrease the total time of treatment, which is beneficial for the patient and reduces the workload.

Study protocol: Optimising patient positioning for the planning of accelerated partial breast radiotherapy for the integrated magnetic resonance linear accelerator: OPRAH MRL

BackgroundAccelerated partial breast irradiation (APBI) is an accepted treatment option for early breast cancer. Treatment delivered on the Magnetic Resonance integrated Linear Accelerator (MRL) provides the added assurance of improved soft tissue visibility, important in the delivery of APBI. This technique can be delivered in both the supine and prone positions, however current literature suggests that prone treatment on the MRL is infeasible due to physical limitations with bore size. This study aims to investigate the feasibility of positioning patients on a custom designed prone breast board compared with supine positioning on a personalised vacuum bag. Geometric distortion, the relative position of Organs at Risk (OAR) to the tumour bed and breathing motion (intrafraction motion) will be compared between the supine and prone positions. The study will also investigate the positional impact on dosimetry, patient experience, and position preference.MethodsUp to 30 patients will be recruited over a 12-month period for participation in this Human Research Ethics Committee approved exploratory cohort study. Patients will be scanned on the magnetic resonance imaging (MRI) Simulator in both the supine and prone positions as per current standard of care for APBI simulation. Supine and prone positioning comparisons will all be assessed on de-identified MRI image pairs, acquired using appropriate software. Patient experience will be explored through completion of a short, anonymous electronic survey. Descriptive statistics will be used for reporting of results with categorical, parametric/non-parametric tests applied (data format dependent). Survey results will be interpreted by comparison of percentage frequencies across the Likert scales. Thematic content analysis will be used to interpret qualitative data from the open-ended survey questions.DiscussionThe results of this study will be used to assess the feasibility of treating patients with APBI in the prone position on a custom designed board on the MRL. It may also be used to assist with identification of patients who would benefit from this position over supine without the need to perform both scans. Patient experience and technical considerations will be utilised to develop a tool to assist in this process.Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN1262400067583. Registered 28th of May 2024. https://www.anzctr.org.au/ACTRN12624000679583.aspx

Non-irradiated area of intraoperative radiotherapy with electron technique: outcomes and pattern of failure in early-stage breast cancer from a single-center, registry study

IntroductionIntraoperative radiotherapy (IORT) with electrons has revealed to have higher rates of ipsilateral breast tumor recurrence (IBTR) than external beam radiotherapy in updated large-scale, randomized controlled trials in 2021. This study details the oncological outcomes of IORT with electron beams using our strict IORT policies. We have found new and important observations regarding the location of recurrence.Methods and materialsThis is a single institution registry of early-stage breast cancer patients who underwent lumpectomy and electron beam IORT with appropriate cone size. All patients met our pre-excision requirements. The primary endpoint was 5-year IBTR rate, with secondary endpoints being 5-year locoregional failure rate, 5-year distant metastasis rate, 5-year overall survival and, importantly, the failure patterns.ResultsBetween January 2011 and December 2022, 124 patients were recruited. The median follow-up was 6.7 years. The 5-year IBTR rate was 1.87% (95% CI 0.47–7.29%), which is much lower than the ELIOT trial and comparable with other accelerated partial breast irradiation (APBI) techniques. The 5-year locoregional failure rate was 3.68% (95% CI 1.40–9.52%), and the 5-year distant metastasis rate was 0.88% (95% CI 0.13–6.12%), while the 5-year overall survival rate was 97.52% (95% CI 92.44–99.19%). Six patients experienced IBTR. All recurrences were in surgical area, occurring superficial to the tumor bed and within 1 cm of the skin dermis. This failure pattern is very unique and might be explained by our hypothesis of the non-irradiated area beneath the skin.ConclusionsIORT with electron beams with strict patient selection criteria and strict large cone size is still an acceptable treatment for select patients with early-stage breast cancer. However, our new findings support extreme caution in the non-irradiated area beneath the skin around the tumor cavity. Given the constraints of our sample size, these findings should be interpreted cautiously and warrant further investigation in larger, more comprehensive studies.

Quality-of-Life Outcomes from NRG/NSABP B-39/RTOG 0413: Whole-breast Irradiation vs Accelerated Partial-breast Irradiation after Breast Conserving Surgery.

NRG Oncology (NRG)/NSABP B-39/RTOG 0413 compared whole-breast irradiation (WBI) to accelerated partial-breast irradiation (APBI). APBI was not equivalent to WBI in local tumor control. Secondary outcome was Quality-of-life (QOL). The QOL sub-study used validated self-report questionnaires including the Breast Cancer Treatment Outcome Scale (BCTOS) and SF-36 vitality scale. Assessments occurred: before randomization, at treatment completion (chemotherapy or radiotherapy), 4-weeks later, at 6-, 12-, 24-, and 36-months. Primary aims: cosmesis change equivalency (baseline to 3 years; a priori margin of equivalence 0.4 standard deviations) and fatigue change superiority (baseline to end-of-treatment (EOT)) for APBI vs WBI, by patient groups treated with or without chemotherapy when appropriate. From 3/21/05-5/25/09, 975 patients enrolled in this sub-study; 950 had follow-up data. APBI had 3-year cosmesis equivalent to WBI (95%CI,-0.0001-0.16; equivalence margin -0.22-0.22) in all patients. The APBI group without chemotherapy had less EOT fatigue (p = .011; mean score APBI 63 vs WBI 59); APBI group receiving chemotherapy had worse EOT fatigue (p = .011; APBI 43 vs WBI 49). The APBI group reported less pain (BCTOS) at EOT (WBI 2.29 vs APBI 1.97), but worse pain at 3-years (WBI 1.62 vs APBI 1.71). APBI patients reported greater convenience of care than with WBI and reported less symptom severity at EOT and 4-weeks later. Cosmetic outcomes were similar for APBI and WBI groups, with small statistically significant differences in other outcomes that varied over time. Differences in fatigue and other symptoms appeared to resolve by ≥ 6 months. APBI may be preferred by some patients, for whom extended treatment is burdensome.

Stereotactic body radiotherapy using CyberKnife versus interstitial brachytherapy in accelerated partial breast irradiation on left-sided breast: A comparison of dosimetric characteristics and preliminary clinical results

IntroductionWe compared the dosimetric characteristics of the target and organs at risk (OARs) as well as the preliminary clinical outcomes between two accelerated partial breast irradiation (APBI) techniques. MethodsForty-four patients diagnosed with left-sided early breast cancer who underwent APBI using either interstitial brachytherapy (IB) or stereotactic body radiation therapy (SBRT) with CyberKnife (CK) were retrospectively reviewed. The dosimetric parameters of the target and OARs were compared. Preliminary clinical outcomes, including tumor control and acute toxicity, were analyzed. ResultsTreatment plans with CK demonstrated a better cardiac dose-sparing effect. Radiation doses to the heart at V150cGy for the CK and IB groups were 24.4 % and 60.4 %, respectively (p < 0.001), while the mean heart doses for the CK and IB groups were 107.4 cGy and 204 cGy, respectively (p < 0.001). The heart D1c.c. and the ipsilateral lung received a lower dose in the IB group, without any significant differences. The median follow-up time in the CK and IB groups was 28.6 and 61.3 months, respectively. No patients died from either breast cancer or cardiac events during follow-up. A locoregional recurrence event at the neck occurred in one patient within the IB group. ConclusionsAPBI planned by CK was shown to have a better dose-sparing effect on the heart, as well as better conformity and homogeneity to the target. CK is a non-invasive treatment which showed minimal acute toxicity and promising tumor control.

Dose Deintensified 3-Day Photon, Proton, or Brachytherapy: A Nonrandomized Controlled Partial Breast Irradiation Trial

BackgroundThe optimal approach for partial breast irradiation (PBI) is unknown. We investigated a novel de-intensified 3-fraction PBI regimen for photons, protons, and brachytherapy. MethodsA multicenter nonrandomized controlled trial with primary outcome of adverse cosmesis at 3 years versus pre-PBI. Eligibility criteria were ≥ age 50 years treated with breast-conserving surgery for node-negative estrogen receptor positive (ER+) invasive breast cancer or any ductal carcinoma in-situ (DCIS) measuring ≤ 2.5 cm. Photon and proton PBI were prescribed 21.9 Gy (RBE) and brachytherapy 21 Gy in 3 fractions. Radiotherapy technique and use of adjuvant endocrine therapy was selected at physician and patient discretion. ResultsBetween June 17, 2015 and July 13, 2017, 161 eligible patients were treated with photons (56), protons (49), or brachytherapy (56). Median patient age was 66.8 years. 126 (78.3%) had invasive breast cancer (all ER+) and 35 (21.7%) had DCIS (88.6% ER+). 54.0% of patients with invasive breast cancer and 25.8% of patients with ER+ DCIS initiated and adhered to prescribed endocrine therapy. The proportion of patients with adverse cosmesis (by trained nurse assessment) was 14.5% at baseline, 2.3% at 3 years (difference -12.2%, 95% CI (-100%, -6.4%)). Adverse cosmesis at last-follow-up, with median follow-up 5 years, was 5.7% by nurse assessment, 5.6% by panel assessment of digital photographs, and 5.2% by patient self-report. There were no observed clinically meaningful changes in other patient reported outcomes, and just two grade 2 or higher adverse events, both grade 2, in the brachytherapy cohort. 5-year local recurrence-free and progression-free survival were 98.0% and 95.5%, respectively. There were no local recurrences amongst 60 patients with invasive breast cancer and Ki67 ≤ 13.25%. ConclusionsDe-intensified 3-day PBI provided favorable disease control, tolerability, and cosmetic outcomes, meeting the pre-specified criteria for acceptability. This approach is an attractive option for small node-negative ER+ BC and DCIS patients. Trial registrationClinicalTrials.gov identifier NCT02453737