5-Fluorouracil (FU) and mitomycin C (MMC) in the management of colorectal carcinoma. Part II. In vitro activity of the two drugs in short-term tumor cultures.

Eighty-seven colorectal adenocarcinomas from untreated patients were investigated by short term tumor cultures to test in vitro sensitivity to 5-fluorouracil and mitomycin C. This study reports the preliminary results of a multistep program aimed at the prospective clinical application of the assay. At present this in vitro experience was performed in parallel with a clinical trial carried out with the same drugs. The in vitro activity of the two anticancer agents is in agreement with the response rate reported in monochemotherapy; our data would suggest an increase of responses using the combination of fluorouracil and mitomycin in comparison to single drug therapy. A low cosensitivity rate and a high number of cases sensitive to one drug but resistant to the other, account for the use of this test as screening of active drugs in the individual patient.