MITOTIC INDEX IN THE SUBRENAL CAPSULE ASSAY AS AN INDICATOR OF THE CHEMOSENSITIVITY OF OVARIAN-CANCER

The subrenal capsule assay (SRCA) is used in clinical oncology to asse ss the sensitivity of individual malignant tumors to various anticance r agents and their combinations. Mitotic indices reflect cancer cell p roliferation and have prognostic value in epithelial neoplasms, includ ing ovarian carcinoma. We combined the two tests (SRCA, mitotic index) by evaluating the numbers of mitotic figures per square millimeter of neoplastic epithelium (MV) in paraffin-embedded tumor samples after S RCA. The M/V index was compared with the tumor size measurement (dTS), which is used in conventional SRCA to predict the drug response. Hist ology examination showed insignificant changes in the size of tumor tr ansplants due to host reaction but disclosed a number of potential err ors in the use of dTS to evaluate transplant growth and drug effects. In our series of 62 patients with advanced ovarian carcinoma the M/V v alue was superior to the dTS in explaining the clinical response after 6 months as assessed at second-look laparotomy. Patients showing no r esponse had significantly higher M/V values than did those displaying complete or partial responses (P < 0.033). The use of 6 mitotic figure s/mm(2) as a limit differentiating responders from nonresponders resul ted in an overall predictive accuracy of 79% in the logistic regressio n analysis. In comparison to the FIGO stage, residual tumor size, and the dTS, the M/V value obtained for the cytostatic combination given t o the patient was the single most significant factor predicting the 6- month clinical response. The results indicate that the combined use of the M/V index and SRCA is a promising new approach to prediction of t he drug response in ovarian adenocarcinoma.