Combined modality therapy of rectal cancer: decreased acute toxicity with the preoperative approach.

PURPOSE: We compared the combined radiation therapy (RT) plus chemotherapy segments of two separate parallel phase I trials to determine if combined pelvic RT, fluorouracil (5-FU), and high-dose leucovorin (LV) had less acute toxicity when delivered preoperatively versus postoperatively in patients with rectal cancer. PATIENTS AND METHODS: Patients with unresectable disease received preoperative RT plus LV and 5-FU followed by surgery and postoperative LV and 5-FU. Patients with resectable disease received identical doses, techniques, and schedules of RT and LV and 5-FU except all therapy was delivered postoperatively. On day 1, patients received LV and 5-FU times one cycle. RT began on day 8. A second cycle of LV and 5-FU was given concurrently with the fourth week of RT. RESULTS: Although more patients (75% v 32%; P = .02) received the higher dose level of 5-FU (250 mg/m2), significantly fewer experienced acute grade 3 to 4 toxicity with preoperative versus postoperative therapy (13% v 48%; P = .045). There was no grade 3 to 4 myelosuppression in either group. The two grade 3 toxicities in the preoperative group were gastrointestinal. The grade 3 toxicities in the postoperative group included seven gastrointestinal and two genitourinary; four patients had a grade 4 toxicity. CONCLUSION: Given the high incidence of grade 3 to 4 toxicity also reported in the postoperative combined modality adjuvant randomized trials, future adjuvant trials should explore the preoperative approach.