Proliferation potential in GH-secreting adenomas: Measurement by monoclonal antibody (MIB-1)

Abstract

The growth fraction of 21 GH-producing macroadenomas was studied retrospectively by im-munohistochemical analysis using the monoclonal antibody MIB-1 (Ki-67 equivalent). Ten patients presented with noninvasive macroadenoma, eleven had invasive macroadenoma. Among the invasive adenomas, 3 patients underwent subtotal removal, and they received postoperative radiation therapy. These patients were followed for 51.1. ± 40.7 months (ranged 4-120 months), but we have not observed tumor regrowth. The mean Ki-67 labeling index (LI) for noninvasive and invasive macroadenomas were 0.77 ± 0.41 %, and 1.1 ± 0.34%, respectively. Although female patients had a higher mean Ki-67 LI than male patients (0.65 ± 1.74 % versus 0.23 ± 1.24 %, p=0.028), there was no significant difference in the mean Ki-67 LI values between invasive and noninvasive adenomas. As a result, the correlation of Ki-67 LI to age, hormonal state, tumor size and invasiveness did not reveal any statistically significant differences.