Unveiling the comorbidity burden of male breast cancer.

Male breast cancer (MBC) is a rare condition with unique characteristics compared to female breast cancer (FBC). Despite its scarceness, there is growing evidence that MBC should not be studied and treated as FBC due to factors like later diagnosis stage and distinct genetic makeup. Retrospective observational study in the EpiChron Cohort, selecting all the prevalent patients with breast cancer between 2010 and 2019. Logistic models were used to determine associated comorbidities. Between 2010 and 2019, 105 MBC and 11,657 FBC patients were found in the EpiChron Cohort. MBC patients had a high mean age at diagnosis and number of comorbidities. Paying attention to comorbidity prevalences in breast cancer patients, it was clear that MBC patients tended to be prone to cardio-metabolic coexisting diseases, while FBC patients were more prone to hormone-, bone- and mental diseases. There were nine chronic conditions associated to MBC patients, but after a year-by-birth matching only four associations remained. Two of them were associated previously [odds ratio (95% confidence interval)]: "Disorder of lipid metabolism" [1.65 (1.03-2.64)] and "Genitourinary symptoms and ill-defined conditions" [2.03 (1.07-3.87)]; and the other two were new, "Anxiety disorders" [2.05 (1.09-3.87)] and "Osteoporosis" [3.58 (1.26-10.14)]. After comparing associated comorbidities in FBC with those in MBC, it seems MBC patients share some of them, but they have their own particular set of coexisting diseases. In fact, once a year-by-birth matching was performed in MBC patient cohort, it was more obvious MBC comorbidities behave more similar to none-Breast-Cancer male population than to FBC patients. These findings highlight the distinct characteristics of the MBC patient population and the need for a tailored approach of managing MBC.