ABSTRACT
Background: To assess outcomes and toxicity after low-energy intraoperative radiotherapy (IORT) for early-stage breast cancer (ESBC). Materials and methods: We reviewed patients with unilateral ESBC treated with breast-conserving surgery and 50-kV IORT at our institution. Patients were prescribed 20 Gy to the surface of the spherical applicator, fitted to the surgical cavity during surgery. Patients who did not meet institutional guidelines for IORT alone on final pathology were recommended adjuvant treatment, including additional surgery and/or external-beam radiation therapy (EBRT). We analyzed ipsilateral breast tumor recurrence, overall survival, recurrence-free survival and toxicity. Results: Among 201 patients (median follow-up, 5.1 years; median age, 67 years), 88% were Her2 negative and ER positive and/or PR positive, 98% had invasive ductal carcinoma, 87% had grade 1 or 2, and 95% had clinical T1 disease. Most had pathological stage T1 (93%) N0 (95%) disease. Mean IORT applicator dose at 1-cm depth was 6.3 Gy. Post-IORT treatment included additional surgery, 10%; EBRT, 11%; adjuvant chemotherapy, 9%; and adjuvant hormonal therapy, 74%. Median total EBRT dose was 42.4 (range, 40.05-63) Gy and median dose per fraction was 2.65 Gy. At 5 years, the cumulative incidence of ipsilateral breast tumor recurrence was 2.7%, the overall survival rate was 95% with no breast cancer-related deaths, and the recurrence-free survival rate was 96%. For patients who were deemed unsuitable for postoperative IORT alone and did not receive recommended risk-adapted EBRT, the IBTR rate was 4.7% versus 1.7% (p = 0.23) for patients who were either suitable for IORT alone or unsuitable and received adjuvant EBRT. Cosmetic toxicity data was available for 83%, with 7% experiencing grade 3 breast toxicity and no grade 4-5 toxicity. Conclusions: IORT for select patients with ESBC results in acceptable outcomes in regard to ipsilateral breast tumor recurrence and toxicity.
ABSTRACT
PURPOSE: There is a lack of level I evidence to guide radiation therapy recommendations for patients receiving neoadjuvant chemotherapy for breast cancer. We used 4 neoadjuvant chemotherapy trials to determine which patients benefit from regional nodal irradiation (RNI). METHODS AND MATERIALS: We obtained data from the NSABP (National Surgical Adjuvant Breast and Bowel Project) B-18, B-27, B-40, and B-41 clinical trials. B-40 and B-41 allowed RNI at physician's discretion. We evaluated locoregional recurrence (LRR), distant recurrence, disease-free survival, and overall survival (OS). Kaplan-Meier, Peto-Peto, χ2, Fisher exact, and Wilcoxon rank-sum tests were used for survival estimates and comparison. RESULTS: Median follow-up for B-18, B-27, B-40, and B-41 was 13.7, 9.7, 4.5, and 5.1 years, respectively, including 742, 2254, 1154, and 504 patients for analysis. On multivariable analysis, factors significantly associated with RNI included tumor size, ypN status, and tumor subtype; Hispanic patients were less likely to receive RNI. Patients with ypN+HER2+ disease who received RNI had improved OS. B-40 patients with ypN+HR+ disease had improved LRR. On multivariable analysis for the B-40 and B-41 study population, RNI was not associated with significantly improved OS, disease-free survival, distant recurrence, or LRR. CONCLUSIONS: RNI was associated with a clinical benefit for patients with ypN+HER2+ and ypN+HR+ disease. RNI was not significantly associated with a clinically beneficial outcome for the entire cohort. Prospective phase 3 clinical trials are needed to establish guidelines for patients who should receive RNI after neoadjuvant treatment, and action is necessary to eliminate the disparity in care delivery shown for Hispanic women.
