ALTERATIONS IN DRUG-SENSITIVITY OF TUMOR-CELLS FROM ASCITIC FLUID AFTER CHEMOTHERAPY OF OVARIAN-CANCER PATIENTS

By means of MTT-assay 47 drug sensitivity tests (to CDDP, CBDCA, ADR, thio-TEPA, 5-FU and VCR) of ascitic fluid tumor cells of 12 ovarian ca ncer patients before and after 2-6 courses of chemotherapy were perfor med. Only in 19 tests no changes in drug sensitivity were recorded. In 21 tests drug sensitivity decreased after treatment of patients (in 1 0 tests - for cytostatics used during chemotherapy and in 11 tests - f or non used). In 7 tests an increase of drug sensitivity (in 4 tests - for cytostatics used during chemotherapy and 3 - for non used) was re ported. The results are discussed. The drug sensitivity of tumor cells in all 12 cases changes during chemotherapy and the development of ac quired resistance is quite common. It can be therefore postulated that such events are not only activated by drug resistance mechanisms but also by an induced selection of tumor cells that significantly alter t he subpopulation structure of the tumor.