Expression of 5α-reductase in apocrine carcinoma of the breast and its correlation with clinicopathological aggressiveness.

ABSTRACT

AIMS: Apocrine carcinomas of the breast frequently lack oestrogen and progesterone receptors and often express androgen receptor. However, little is known about the role of androgen in apocrine carcinoma. Androgen-producing enzymes, such as 5α-reductase (5αR), which converts testosterone locally to the potent androgen dihydrotestosterone, have recently gained attention in studies of the intratumoural actions of androgens. The goal of this study was to examine 5αR expression and its relationship to other clinicopathological factors in apocrine carcinoma. METHODS AND RESULTS: Of 48 cases of infiltrating apocrine carcinoma, 30 cases (62.5%) were immunopositive for 5αR. Twenty-seven of the 5αR-positive cases were also positive for androgen receptor. In comparison to 5αR-negative cases, 5αR-positive cases showed clinicopathological aggressiveness characterized by significantly larger infiltrating tumour size (P = 0.001), higher frequency of lymphatic (P = 0.029) and vascular invasion (P = 0.009), higher histological grade (P = 0.048) and shorter recurrence-free survival time (P = 0.047). No significant differences in nuclear grade, hormonal receptors, human epidermal growth factor receptor 2 (HER2) or p53 protein were detected between two groups. All five cases of intraductal apocrine carcinoma lacked 5αR. CONCLUSION: Approximately 60% of infiltrating apocrine carcinomas were immunopositive for 5αR. The 5αR-positive apocrine carcinomas were clinicopathologically more aggressive than 5αR-negative cases. Our findings suggest that autocrine androgen synthesis accelerates tumour aggressiveness in apocrine carcinoma.