THE CORRELATION OF KI-67 STAINING INDEXES WITH TUMOR DOUBLING TIMES IN REGROWING NONFUNCTIONING PITUITARY-ADENOMAS

In order to improve our ability to predict the regrowth of nonfunction ing pituitary adenomas, we tried to assess the correlation between gro wth fractions with Ki-67 and PCNA (proliferating cell nuclear antigen) and tumour doubling times in regrowing tumours, and also to find out any difference of growth fractions between the regrowing and the cured cases. In 33 patients with non-functioning pituitary adenomas, 14 cas es including 11 with cavernous sinus invasion showed residual tumour o n MRI after the operation (regrowing group) and 19 cases had no tumour regrowth on MRI within 5 years after the operation (cured group). Imm unocytochemical studies were done with monoclonal antibodies (anti-PCN A, anti-Ki-67: MIB-1). The growth fraction of each tumour was estimate d by calculating the ratio of the positive nuclei to the total number of tumour cells with the aid of an image analyser (Mac SCOPE). The tum our doubling times were estimated from serial CT or MRI with the aid o f the image analyser (NIH image). Ki-67 staining; indices ranged from 0.2% to 1.5% (n = 14, 0.86+/-0.10%; mean+/-SEM) in the regrowing group , and from 0.1% to 0.5% (n = 19, 0.23+/-0.03%) in the cured group. PCN A staining indices of the regrowing group ranged from 0.6% to 24% (n = 14, 3.7+/-1.6%). In the regrowing group, the tumour doubling times ra nged from 200 to 2550 days (930+/-180 days), and showed a significant inverse correlation with Ki-67 staining indices, but no correlation wi th PCNA staining indices. The regrowing group showed a significantly h igher Ki-67 staining index (n = 14, 0.86+/-0.10%) than the cured group (n = 19, 0.23+/-0.03%) (p<0.01). These results indicate that immunocy tochemical studies using MIB-1 may be better than those with PCNA for the prediction of regrowth in non-functioning pituitary adenomas. Immu nocytochemical study with MIB-1 could lead to the accurate prediction of the rapid regrowing lesions in non-functioning adenomas.