Breast
CME
Gili G. Halfteck, MD, PhD (she/her/hers)
Breast Surgical Oncology Fellow
University of Texas Medical Branch
Galveston, Texas, United States
Disclosure(s): No financial relationships to disclose
Gili G. Halfteck, MD, PhD (she/her/hers)
Breast Surgical Oncology Fellow
University of Texas Medical Branch
Galveston, Texas, United States
Disclosure(s): No financial relationships to disclose
Efstathia Polychronopoulou, MsC
statistician
University of Texas Medical Branch
Galveston, Texas, United States
Disclosure information not submitted.
Waqar Haque, MD
Radiation Oncologist
University of Texas medical Branch, United States
Disclosure information not submitted.
Roi Weiser, MD
Fellow
University of Texas Medical Branch
Houston, Texas, United States
Disclosure information not submitted.
Sandra S. Hatch, MD
Chief of Radiation Oncology
University of Texas Medical Branch, United States
Disclosure information not submitted.
The 21-gene recurrence score (RS) is used to predict benefit from chemotherapy in HR-positive breast cancer with 1-3 positive lymph nodes. We aimed to assess whether it could be utilized in a similar manner to predict a survival benefit from post-mastectomy radiation therapy (XRT).
Methods: The NCDB was used to identify women 50-75 years of age with HR+, HER2-negative, T1-3, N1, M0 breast cancer who underwent mastectomy and axillary staging with available RS during the years 2010 to 2015. Kaplan-Meier and Cox proportional hazards models were used to identify association between treatment and OS. Univariate and multivariate analyses were used to identify variables correlating with XRT and OS.
Results: A total of 8907 patients were identified. 3203 (36%) patients received adjuvant chest wall XRT and 5704 (64%) did not. Across the entire cohort, 5-years OS was 97.5% and for patients receiving XRT and 96.8% for those who did not (p=0.063). After adjusting for all covariates, in patients with RS<25, there was no statistically significant improvement in 5-years OS when adjuvant XRT was added or not (Figure 1, 97.5% vs. 98.1% P=0.093). Moreover, no survival benefit was seen with axillary node dissection (P=0.58) or with the addition of chemotherapy (P=0.312).
Conclusions: In our cohort of patients with one to three positive nodes and a RS <25, omission of post-mastectomy radiation therapy had no impact on OS. Our results show that RS can be utilized to predict benefit from adjuvant XRT and questions the need to “radiate the un-dissected axilla” in this cohort.