A prospective randomized comparison of protracted infusional 5-fluorouracil with or without weekly bolus cisplatin in metastatic colorectal carcinoma. A Mid-Atlantic Oncology Program study. One hundred eighty-four patients with advanced measurable colorectal cancer not previously treated with chemotherapy were entered into a prospective randomized clinical trial by the Mid-Atlantic Oncology Program (MAOP) to assess the value of weekly cisplatin (20 mg/m2) when added to a protracted schedule of 5-fluorouracil (5-FU) infusion (PIF) at 300 mg/m2/d for 10 weeks of every 12 weeks. The liver was the primary indicator lesion in approximately 75% of the study group. All tumor measurements required radiographic confirmation. The response rate in the PIF alone arm was 35% (29 of 83; 95% confidence interval [CI], 25% to 46%) compared with 33% (28 of 85; 95% CI, 23% to 44%) for the arm in which weekly cisplatin was added to PIF. The median survival times were 11.8 and 11.2 months in the two groups. Weekly cisplatin does not appear to add to the effectiveness of PIF in colorectal carcinoma. 