Radiation delivery in patients undergoing therapeutic nipple-sparing mastectomy

Although guidelines exist for radiation delivery in the setting of mastectomy or breast-conservation therapy, radiation delivery after nipple-sparing mastectomy (NSM) remains variable. Our goal is to determine whether patients who undergo therapeutic NSM are more likely to receive radiation than patients who undergo non-NSM and whether National Comprehensive Cancer Network (NCCN) guidelines for radiation after mastectomy are observed in NSM patients.

Female patients who underwent NSM or non-NSM for breast cancer from 2006 to 2010 were isolated from the Surveillance, Epidemiology, and End Results database. Univariate analysis stratified by tumor size and lymph node status, and multivariate analyses were used to compare odds of radiation in NSM and mastectomy patients. Adherence to NCCN guidelines based on tumor size and lymph node status was also investigated.

A total of 112,817 patients were included: 470 (0.4 %) underwent NSM, and 112,347 (99.6 %) underwent non-NSM. NSM patients with 0 nodes/size ≤2 cm, 0 nodes/size 2-5 cm, and unexamined axilla/size ≤2 cm had higher odds of radiation when compared with size- and node-matched mastectomy patients. Multivariate logistic regression showed that NSM patients had higher odds of radiation (odds ratio 2.01, p < 0.001) than mastectomy patients. Radiation was given to 18 % of NSM patients who did not meet NCCN guidelines according to size or lymph node involvement, compared with 6 % of mastectomy patients.

Patients who undergo therapeutic NSM are more likely to receive radiation compared with mastectomy patients. This may reflect a concern with leaving ductal tissue in the nipple-areolar complex.