JOURNAL OF HEMATOLOGY

Full list of author information is available at the end of the articleMale breast cancer (MBC) is an uncommon malignancy accounting for less than 1 % of all breast cancer (BC) cases [1], albeit its incidence is rising [2]. The hormone-driven nature of the disease was postulated in the 1940s [2] and corroborated over the past decades by studies reporting on hormone receptor expression [3, 4]. Results from the National Cancer Institute’s Surveillance, Epi-demiology, and End Results (SEER) database revealed [4]. Thus, antiestrogen therapy currently represents the mainstay of treatment for these patients, even though the use of tamoxifen [5], aromatase inhibitors (AIs) [6–8], and fulvestrant [9, 10] was investigated only retro-spectively in small-sized cohorts. A therapeutic role for the androgen receptor (AR) was also envisioned [11–13] and corroborated by immunohistochemical analysis and gene-expression-profiling studies [3, 14]. Analysis of a large MBC cohort documented AR immunoreactivity in 64 % of cases [3], and over-expression of AR-related pathway components was reported [14]. Despite the wealth of hormonal treatments that hav