Surgery for Men with Breast Cancer: Do the Same Data Still Apply?

BACKGROUND: Men represent a small proportion of breast cancer diagnoses, and they are often excluded from clinical trials. Current treatments are largely extrapolated from evidence in women. We compare practice patterns between men and women with breast cancer following the publication of several landmark clinical trials in surgery. PATIENTS AND METHODS: Patients with invasive breast cancer (2004-2015) from the National Cancer Data Base were identified; subcohorts were created based on eligibility for NSABP-B06, CALGB 9343, and ACOSOG Z0011. Practice patterns were stratified by gender and compared. Cox proportional hazards regression analyses were utilized to estimate the association between OS and gender. RESULTS: Of the 1,664,746 patients identified, 99% were women and 1% were men. Among NSABP-B06 eligible men, mastectomy rates did not change (consistently ~ 80%), and their adjusted OS was minimally worse compared with women (HR 1.19, 95% CI 1.11-1.28). Following publication of CALGB 9343, omission of radiation after lumpectomy was less likely in men and lagged behind that of women, despite similar OS (male HR 0.92, 95% CI 0.59-1.44). Application of ACOSOG Z0011 findings resulted in deescalation of axillary surgery for men and women with comparable OS (male HR 0.69, 95% CI 0.33-1.45). CONCLUSIONS: Uptake of clinical trial results for men with breast cancer often mirrors that for women, despite exclusion from these studies. Furthermore, when study findings were applied to eligible patients, men and women demonstrated similar survival. Observational studies can help inform the potential application of study findings to this unique population and improve patient enrollment in clinical trials.