Assessment of infusional 5-fluorouracil schedule and dose intensity: a Southwest Oncology Group and Eastern...

Building on results from Southwest Oncology Group trial 8905, this trial was designed to compare low-dose continuous infusion (LDCI) of 5-fluorouracil (5-FU) versus intermittent high-dose infusion (HDI) of 5-FU in disseminated colorectal cancer (CRC) for evidence of survival advantage based on dose intensity. A companion trial was funded to assess molecular parameters associated with fluoropyrimidine response or resistance and toxicity from these treatments.

Eligibility included histologic diagnosis of disseminated CRC, measurable or evaluable disease, no previous therapy for metastatic disease, performance status of 0-2, and adequate renal, hepatic, cardiac, and hematologic function. Stratification factors were measurable versus evaluable disease, performance status of 0/1 versus 2, presence versus absence of adjuvant therapy, and presence versus absence of previous surgery and enrollment on the companion trial. Patients were randomized to receive (1) LDCI 5-FU 300 mg/m(2) per day for 28 days every 5 weeks or (2) HDI 5-FU 2,600 mg/m(2) for 24 hours each week.

Between April 1995 and May 1999, 730 patients were accrued (LDCI arm, n = 360; HDI arm, n = 370). Of these, 708 eligible patients were assessable for survival and 690 for toxicity. Median survival for both groups was 13 months. Toxicity was mild; < 10% of patients in both arms had grade > 4 events. There were 8 study-related deaths (1%). Less than 10% of patients were enrolled in the companion trial.

Increasing 5-FU dose intensity yields no survival advantage beyond that achieved with LDCI 5-FU. This study confirms the favorable toxicity profile of infusional 5-FU. Because no preferential benefit was observed for either infusion schedule, the more convenient weekly schedule should be considered for 5-FU-based combination regimens for disseminated CRC.