Evolution of Male Breast Cancer Treatment: Results from Twenty Years of BreastSurgANZ Quality Audit Data.

PURPOSE:Treatment of breast cancer in female patients has evolved over the past 20 years to improve outcomes, however it is unclear to what extent treatment has evolved in male patients. This bi-national registry observational study examined the disease burden and treatment landscape for new diagnoses of male breast cancer undergoing surgical management in Australia and New Zealand in comparison to females. METHODS:A twenty-year study of male breast cancer patients compared to females was conducted for the period of 2003-2022 using the Breast Surgeons of Australia and New Zealand Quality Audit (BQA) database. Demographic, histological and treatment data was analysed according to biological sex and decade of breast cancer diagnosis (2003-2012 versus 2013-2022). RESULTS:Data from 258,246 patients (1542 males, 256,704 females) were analysed. Treatment of male breast cancer was largely unchanged in the later decade compared to the earlier decade apart from sentinel lymph node biopsy uptake which was significantly higher in the later decade (66% vs 47%, p < 0.001). In contrast, significant differences in both surgical and adjuvant therapies were noted in the female group for every domain except post-mastectomy radiotherapy. Females treated early in the study period were associated with higher rates of adjuvant chemotherapy use than those treated in the later decade (OR 1.10, 95%CI 1.10; 1.11, p < 0.001), while adjuvant chemotherapy use was stable over time in the male group. CONCLUSIONS:In Australia and New Zealand there has been a de-escalation in axillary surgery for male breast cancer during the multimodality era. This evolution has been modest compared to the extensive changes in therapy for female breast cancer in line with formalised treatment guidelines.