Gender-related differences in prolactinomas. A clinicopathological study.

BACKGROUND/AIMS: Prolactinomas are the most common tumors of the pituitary gland. Only few studies have documented gender-related differences in the growth and presentation of these tumors, but nothing is known about their effects on their subsequent surgical outcome and prognosis.

PATIENTS & METHODS: Twenty-six patients with prolactinomas, that met strict immunohistochemical and electron microscopic criteria and were surgically treated between January 1990 and June 1997, were retrospectively reviewed. The patient charts, as well as histological (mitotic index) immunohistological (MIB-1 labeling-index) and electronic microscopical staining were analyzed.

RESULTS: Nineteen patients were women, and seven were men; the female-to-male-ratio was 2.7:1. Men were significantly older, both at diagnosis and surgery. Menstrual abnormalities were the most common presenting symptom in women, whereas impotence predominated in men. Psychological symptoms were significantly more common in men than in women. Men had a significantly shorter preoperative duration of symptoms and higher preoperative serum prolactin levels than women. The preoperative prolactin levels and proliferative activities (mitotic index, MIB-1 labeling index) were lower in women compared to men and showed a direct correlation to postoperative outcome. The overall outcome was significantly better in women than in men. In women, age less than 35 years was a beneficial prognostic factor, and preoperative bromocriptine treatment was associated with a significantly worse long-term-outcome.

CONCLUSION: The biology and the clinical course of prolactinomas seem to differ in women and men. In men, the preoperative durations of symptoms is shorter, the tumors are larger and more invasive at surgery, and the outcome is worse than in women. Based on proliferative activities (mitotic index, MIB-1 labeling index), the predominance of marcoadenomas in men is due to a high frequency of rapidly growing tumors, which are often invasive and frequently correlated with a worse outcome. Our findings may justify a more aggressive therapeutic approach to prolactinomas in men than in women.