e12608 Background: Post-mastectomy radiation (PMRT) reduces the risk of locoregional failure for women with an elevated risk of recurrence from breast cancer. Therefore, PMRT is often indicated for women with node positive breast cancer including those with only 1-3 nodes involved. The need for PMRT in node negative breast cancer patients is less established. The objective of our study was to review the predictors of PMRT in women with node-negative breast cancer and evaluate the overall recurrence rates. Methods: A retrospective chart review was completed. Women with node-negative breast cancer who underwent mastectomy and sentinel lymph node biopsy at a regional breast cancer center between January 1st,2011 and December 31st, 2017 were included. Patient and tumor characteristics, treatment details and recurrence data were recorded. The primary outcome was recommendation of PMRT. Univariate analysis was completed and then a multivariable logistic regression was completed to determine independent predictors for PMRT. Results: Overall, 235 women with node-negative breast cancer underwent mastectomy and sentinel lymph node biopsy during the study period. Forty-three (18.3%) patients were recommended to undergo PMRT, with 39 of the 43 patients completing the recommended treatment. PMRT was offered more often to younger women (p<0.001), women with multifocal/centric disease (p=0.002), large tumors (p<0.001), high grade tumors (p < 0.001), lymphovascular positive tumors (p=0.04) and estrogen-negative disease (p =0.017). On multivariable analysis, the odds of radiation recommendation were highest for patients with high grade disease (OR 5.81, 95%CI: 2.08 – 16.20) followed by multifocal/centric disease (OR 3.12, 95%CI: 1.26 – 7.70). There were no differences in overall recurrence between patients who underwent PMRT versus those who did not have PMRT (p = 0.31). Conclusions: A moderate percentage of node negative patients are offered PMRT. Independent predictors for recommendation of PMRT in node negative patients are: decreasing age, increasing tumor size, multifocal/centric disease and higher grade disease. Surgeons can use this information to counsel patients regarding the possible need for PMRT, especially in the setting of planned immediate reconstruction.
A Comparison of Outcomes for the Patients with Pathologically Node-negative Breast Cancer and Who Were Treated Either with Sentinel Lymph Node Biopsy Only or with Conventional Axillary Lymph Node Dissection
