CDK4 and breast cancer: As the incidence of male breast cancer has been steadily increasing over the past decades [7, 36, 37] and the average time to diagnosis still lies at 6–10 months after observation of first symptoms [38] (mainly attributed to a lack of knowledge, public education and embarrassment [39]), we are bound to see more and more male patients with eBC who are eligible for adjuvant therapy with a CDK4/6 or PARP inhibitor.