Gender-related differences in non-functioning pituitary adenomas

Clinically non-functioning pituitary adenomas are common tumors of the pituitary gland. No studies have yet documented gender-related differences in the growth and presentation of these tumors and nothing is known about their effects on their subsequent surgical outcome and prognosis.

Twenty-eight patients with non-functioning pituitary adenoma, that met strict inclusion criteria, and that underwent surgical treatment between January 1990 and June 1997, were retrospectively reviewed.

The patient charts, as well as histological (incl. immunohistochemistry) and electron microscopic findings were analyzed. Tumor invasiveness was classified according to the modified Hardy criteria.

Eleven patients were women and seventeen were men; the female-to-male-ratio was 1:1.5. Men were significantly older, both at diagnosis and surgery. Visual field defect and visual acuity deficit were the most common presenting symptoms with similar occurrence both in women and men, whereas blindness predominated in women. Microadenomas and invasive adenomas did not differ significantly in MIB-1 index, but patients less than 35 years old had higher MIB-1 indices (n=4, 1.72+/-1.15), than did patients over 45 years (n=11, 0.63+/-0.42) (p: n.s.). MIB-1 labeling indices were higher in adenomas of female compared to male patients (1.5 +/-1.2 vs. 0.8+/-1.8; p < 0.003). The overall outcome was significantly worse in women than in men.

The biology and the clinical course of clinically non-functioning pituitary adenoma seem to differ in women and men. In men, tumors are smaller and less invasive at surgery, and the outcome is better than in women. The present findings may justify a more aggressive therapeutic approach to clinically non-functioning pituitary adenomas in women than in men, especially to improve the availability of viable pituitary cells at the time of surgery.