Clinicopathological, multimodal treatment, and survival patterns for men with breast cancer in England and Wales: a population-based cohort study.

Background: Male breast cancer (BC) is rare and understudied, and the incidence is increasing. This study evaluated clinicopathological, multimodal treatment and survival patterns for men with BC (versus women) in England and Wales as part of the National Audit of Primary Breast Cancer (NAoPri). This audit is commissioned by the Healthcare Quality Improvement Partnership on behalf of NHS England and the Welsh government. Methods: This retrospective population-based cohort study used pseudonymised patient- and tumour-level data for all adults (≥18 years) who were newly diagnosed (as per ICD-10 codes C50 and D05.1) with BC between Jan 1, 2015, and Dec 31, 2021 in England and Wales, supplied by the English National Cancer Registries and Analysis Services (NCRAS) and Wales Cancer Network (WCN), respectively. Cancer registration data were linked to various national datasets. Risk-adjusted treatment patterns for men and women with oestrogen-receptor (ER) positive early invasive breast cancer (EIBC) were analysed using multivariable logistic regression. Flexible parametric survival models and competing risk analysis estimated 5-year overall and cause-specific survival. Findings: Of the 340,164 people diagnosed during the study period, 2463 men (England: 2346, Wales: 117) were compared to 337,701 women. Men were older with more comorbidities and increased frailty burden. Men had more locally advanced, higher-grade, ER-positive, HER2-negative disease. Men with ER-positive EIBC had more surgery after age 70 years, less frequently received neo-adjuvant chemotherapy (adjusted odds ratio [aOR] 0.63; 95% confidence interval (95% CI) 0.44-0.90) and more often received post-mastectomy radiotherapy for intermediate- and low-risk disease (aOR 1.28; 1.05-1.56 and aOR 2.61; 2.19-3.12). Endocrine therapy use was equivalent (aOR 1.46; 0.92-2.32). Breast cancer-specific death was comparable for men and women, respectively (standardised cumulative incidence function [CIF] 3.6% [95% CI: 2.9%-4.5%] vs 4.6% [4.5%-4.7%]). Death from other causes was greater in men (standardised CIF 12.0% [10.8%-13.2%] vs 7.7% [7.6%-7.8%]). Interpretation: These findings show that men with breast cancer presented differently to women. Despite breast cancer-specific survival being comparable for men and women, there were notable differences in the management of men with ER-positive EIBC which require further exploration, including increased surgery among older men, reduced neo-adjuvant chemotherapy, and increased post-mastectomy radiotherapy for intermediate- and low-risk disease. Funding: None.