Value of adjuvant radiation therapy in breast cancer patients with one to three positive lymph nodes undergoing a modified radical mastectomy and systemic therapy

Abstract

507 Background: Whether adjuvant radiation therapy should be utilized for patients (pts) with early stage breast cancer with up to 3 positive axillary lymph nodes treated with mastectomy and systemic therapy is controversial. This retrospective study was performed to determine if adjuvant radiation therapy had an impact on survival for this cohort of pts. Methods: 4240 pts with T1–2N0–1 breast cancers, diagnosed between 1980–2007, who underwent either mastectomy without adjuvant radiation therapy or segmental mastectomy with adjuvant radiation therapy were identified. All pts received systemic treatment. Women with >3 positive axillary lymph nodes were excluded. Overall (OS) and distant disease free survival (DDFS) were estimated using the Kaplan-Meir product method. Cox proportional hazards were used to determine associations between OS/DDFS and type of surgery after controlling for pt and disease characteristics. Results: 1336 (18.8%) had T1N0 disease, 1114 (26.27%) had T2N0 disease, 989 (23.33%) had T1N1 disease and 801 (18.89%) had T2N1 disease. Median follow-up was 54 months.5- year DDFS among women who underwent mastectomy and segmental mastectomy was 81% (95% 78%-83%) and 86% (95% CI 84%-87%), respectively (p < 0.0001). In the Cox analysis, pts who had mastectomy without radiation had a significantly increased risk of distant recurrence (HR= 1.39, 95% CI 1.14–1.70, p= 0.0013) than pts treated with segmental mastectomy and radiation. When looking at subgroups, no significant difference in DDFS was observed between the two groups in pts with lymph node negative disease. However, for pts with 1–3 positive lymph nodes, pts treated with mastectomy without radiation had significantly increased risk of distant recurrence compared to pts treated with segmental mastectomy with radiation (HR=1.614, 95% CI 1.198–2.177, p= 0.002). This difference was most pronounce in the subset of patients with T2N1 disease (HR= 1.794, 95% CI 1.220–2.637, p=0.003). Similar trends were observed for OS. Conclusions: This study provides provocative evidence for benefit of radiation therapy among pts with 1–3 positive axillary lymph nodes who are treated with surgery and systemic therapy. No significant financial relationships to disclose.