Randomized trial of postoperative adjuvant chemotherapy with or without radiotherapy for carcinoma of the rectum: National Surgical Adjuvant Breast and Bowel Project Protocol R-02

Background: The conviction that postoperative radiotherapy and chemotherapy represent an acceptable standard of care for patients with Dukes' B (stage II) and Dukes' C (stage III) carcinoma of the rectum evolved in the absenc e of data from clinical trials designed to determine, whether the addition of radiotherapy results in improved disease-free survival and overall survi val. This study was carried out to address this issue. An additional aim wa s to determine whether leucovorin (LV)-modulated 5-fluorouracil (5-FU) is s uperior to the combination of 5-FU, semustine, and vincristine (MOF) in men . Patients and Methods: Eligible patients (n = 694) with Dukes' B or C carc inoma of the rectum were enrolled in National Surgical Adjuvant Breast and Bowel Project (NSABP) Protocol R-02 from September 1987 through December 19 92 and were followed. They were randomly assigned to receive either postope rative adjuvant chemotherapy alone (n = 348) or chemotherapy with postopera tive radiotherapy (n = 346). All female patients (n = 287) received 5-FU pl us LV chemotherapy; male patients received either MOF (n = 207) or 5-FU plu s LV (n = 200), Primary analyses were carried out by use of a stratified lo g-rank statistic; P values are two-sided, Results: The average time on stud y for surviving patients is 93 months as of September 30, 1998. Postoperati ve radiotherapy resulted in no beneficial effect on disease-free survival ( P = .90) or overall survival (P = .89), regardless of which chemotherapy wa s utilized, although it reduced the cumulative incidence of locoregional re lapse from 13% to 8% at 5-year follow-up (P = .02). Male patients who recei ved 5-FU plus LV demonstrated a statistically significant benefit in diseas e-free survival at 5 years compared with those who received MOF (55% versus 37%; P = .009) but not in 5-year overall survival (65% versus 62%; P = .17 ). Conclusions: The addition of postoperative radiation therapy to chemothe rapy in Dukes' B and C rectal cancer did not alter the subsequent incidence of distant disease, although there was a reduction in locoregional relapse when compared with chemotherapy alone.