Long-term outcomes of post-mastectomy radiation therapy in the setting of neoadjuvant chemotherapy for locally advanced breast cancer.

e12030 Background: The role of post-mastectomy radiation therapy (PMRT) after neo-adjuvant chemotherapy (NCT) in those with T3N0 disease, younger age, and different tumor subtypes is unclear. Methods: We conducted a single institution, retrospective analysis of patients treated with NCT and mastectomy from 1985-2010. The primary objectives were to (1) assess the association between PMRT and long-term outcomes, and (2) describe outcomes and practice patterns based on tumor subtype, pathologic response, and age at diagnosis. Secondary objectives were to analyze the benefit of PMRT in those with favorable tumor subtypes, cT3N0 disease, and patients younger than 40. Log-rank test and Cox regression was used to test the association of predictors with outcomes. IRB approval was obtained. Results: Of 131 evaluable patients, 115 (88%) received PMRT. Mean±SD age was 48±10 years (range 29-79). Of patients <40 years of age (n=33) 88% received PMRT. At diagnosis, 69.5% were cT3; 53.5% were cN1; 12.3% were cT3N0. Seve...