Gender-related differences in growth hormone-releasing pituitary adenomas. A clinicopathological study

Background/Aims: Pituitary adenomas are the third most common primary intracranial neoplasm, after astrocytomas and meningiomas, and about 30% of them secrete growth hormone (GH). Other subtypes of pituitary tumors are characterized by well-known gender-related differences, not only in clinical presentation and other biological characteristics but also in surgical outcome. For GH-releasing pituitary adenomas, however, detailed data on gender differences of postsurgical treatment are not available. Patients and methods: The patient charts of a series of 18 patients with acromegaly who met strict immunohistochemical and electron microscopic criteria and who underwent surgical resection of their tumors between January 1990 and June 1999 were retrospectively reviewed. Results: There were eight women and ten men; the male-to-female-ratio was 1.3:1. The men and women were equal in age at surgery. Men demonstrated higher lGF-1 and smaller GH levels pre- and postoperatively, whereas the reduction in IGF-1 was more pronounced compared to women (58% vs. 27%). The overall outcome was better in women than in men. Mixed GH- and prolactin-secreting adenomas showed a worse outcome among all other histological subtypes. Mitose- and MIB-1 labeling index was increased in men compared to women. Conclusion: The clinical course and tumor biology of GH-releasing pituitary adenomas appear to differ in women and men. Men demonstrated a shorter preoperative duration of symptoms, larger and more invasive tumors, and a worse clinical outcome. These findings suggest that therapy for GH-releasing adenomas should be more aggressive in men than in women. The gender-related differences in GH-releasing pituitary adenomas appear to have a basis in different biologic behavior, which warrants further investigation.