Prior to the standard use of preoperative chemoradiation for stage II and III rectal cancer, several studies established the benefits of adjuvant combined-modality therapy for surgical stage II and III disease. Intergroup protocol 86-47-51 (MAYO-864751) demonstrated a 10% improvement in overall survival (OS) with the use of continuous-infusion 5-FU (225 mg/m2 /day throughout the entire course of radiation therapy) compared with bolus 5-FU (500 mg/m2 /day for three consecutive days during the first and fifth weeks of radiation).[Level of evidence: 1iiA] The final results of Intergroup trial 0114 (CLB-9081) showed no survival or local-control benefit with the addition of leucovorin (LV), levamisole, or both to 5-FU administered postoperatively for patients with stage II and III rectal cancers at a median follow-up of 7.4 years.[Level of evidence: 1iiA]
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Another study, (SWOG-9304 [NCT00002551]), was a three-arm randomized trial that was designed to determine whether continuous-infusion 5-FU throughout the entire standard six-cycle course of adjuvant chemotherapy was more effective than continuous 5-FU only during pelvic radiation and included the following:
Arm 1 received bolus 5-FU in two 5-day cycles before (500 mg/m2 /day) and after (450 mg/m2 /day) radiation therapy, with protracted venous infusion 5-FU (225 mg/m2 /day) during radiation therapy.
Arm 2 received continuous infusion 5-FU before (300 mg/m2 /day for 42 days), after (300 mg/m2 /day for 56 days), and during (225 mg/m2 /day) radiation therapy.
Arm 3 received bolus 5-FU plus LV in two 5-day cycles before (5-FU 425 mg/m2 /day; LV 20 mg/m2 /day) and after (5-FU 380 mg/m2 /day; LV 20 mg/m2 /day) radiation therapy, and bolus 5-FU plus leucovorin (5-FU/LV) (5-FU 400 mg/m2 /day; LV 20 mg/m2 /day; days 1 to 4, every 28 days) during radiation therapy. Levamisole (150 mg/day) was administered in 3-day cycles every 14 days before and after radiation therapy.