PROLIFERATION IN ADRENOCORTICAL TUMORS - CORRELATION WITH CLINICAL OUTCOME AND P53 STATUS

There appears to be a relationship between mitotic activity and malign ant behavior in adrenocortical tumors, and carcinomas with a high mito tic index may have a poorer prognosis. This has been investigated furt her by quantifying and comparing the Ki-67 index using antibody MIB-1 in a series of 14 adrenocortical adenomas and 40 carcinomas. The level s have been correlated with survival and disease-free survival in carc inomas and with evidence of abnormal p53 expression as detected by imm unohistochemistry. Nevertheless, many carcinomas have a low level of p roliferation that may reflect varying abnormalities within the regulat ion of both cell division and apoptosis. Expression of bcl-2 protein, an inhibitor of apoptosis has therefore also been examined. The Ki-67 index in carcinomas was significantly higher than in adenomas, but bel ow 4% there was overlap. There was no significant difference in surviv al between carcinomas with MIB-1 index <3% and those greater, but the lower group had significantly longer disease-free survival (p = 0.02). There was no significant difference between p53 immunopositive and p5 3 immunonegative carcinomas. No tumor showed immunopositivity for bcl- 2 protein. It is concluded that MIB-1 index may contribute additional prognostic information in adrenocortical tumors. Inhibition of apoptos is by bcl-2 does not appear to play a role in tumor growth.