PROGNOSTIC IMPLICATIONS OF CHEMORESISTANCE-SENSITIVITY ASSAYS FOR COLORECTAL AND APPENDICEAL CANCER

A major problem with pharmacologic treatments for cancer is the unpred ictable nature of the clinical response. Therefore many patients are t reated but few benefit from chemotherapy. Selection of patients for dr ug treatment would greatly benefit both responders and nonresponders. Mitomycin C (MMC) and 5-fluorouracil (5-FU) are important drugs widely used in the treatment of patients with gastrointestinal malignancies. In a prospective study, an in vitro chemoresistance-sensitivity assay (CR-SA) was performed for 95 patients at the time of surgery for peri toneal carcinomatosis from colorectal and appendiceal cancer. Followin g cytoreductive surgery, all of these patients had minimal-to-moderate residual disease. All patients were treated with the same chemotherap y regimen regardless of the results of the in vitro assay in the posto perative period, Clinical status of patients was correlated to the ass ay predictions, and the results were statistically evaluated. When res istance was correlated with outcome, there was no statistical differen ce. In addition, the mean percentage of growth inhibition was not incr eased when responders and nonresponders were compared. Finally, more p atients who had greater than or equal to 95% in vitro growth inhibitio n of cancer did not survive than did those with <95% growth inhibition . The in vitro test did not predict sensitivity or resistance to cance r when regional chemotherapy was administered in a clinical setting of peritoneal carcinomatosis.