What is your approach to adjuvant endocrine therapy in hormone receptor positive male breast cancers?

Tamoxifen should be the standard adjuvant endocrine therapy for ER+ breast cancer in men. There has been talk intermittently about aromatase inhibitor (AI) use as alternative endocrine therapy, and I would not recommend the use of AIs in this setting. Data is limited, with the one study comparing outcomes (Eggemann et al, BCRT 2013) in 257 men with ER+ breast cancer, showing inferior outcome after AI vs Tamoxifen.

It is important to note that gonadal physiology in men resembles premenopausal rather than postmenopausal women; another reason to avoid AI use in the adjuvant setting of ER+ breast cancer in men. AI+ LHRH agonists maybe appropriate to consider under certain circumstances, but data is limited.

Until we have more data, tamoxifen shou...

I agree that tamoxifen remains the standard adjuvant therapy (including extended therapy for higher risk cases), and if tamoxifen is contraindicated, GnRH agonist/antagonist plus aromatase inhibitor as recommended by the ASCO Guidelines for male breast cancer (Hassett et al., PMID 32058842).