QUASAR: A randomized study of adjuvant chemotherapy (CT) vs observation including 3238 colorectal cancer patients.

3501 Background: The size of survival benefit from adjuvant fluorouracil/folinic acid (FUFA) CT for colorectal cancer is unclear. METHODS: Patients with apparently curative resections of colon or rectal cancer were randomized following surgery between FUFA and observation (with CT considered on recurrence). CT consisted of either six 5-day, four-weekly or 30 once-weekly courses of intravenous fluorouracil (370mg/m(2)) with either high-dose (175mg) or low-dose (25mg) L-folinic acid, and with either levamisole or placebo. Primary outcome was all cause mortality. RESULTS: Between June 1994 and December 2003, 3238 patients (91% Dukes B, 71% colon cancer, median age 63) from 150 centres in 17 countries were randomised. Direct randomised comparisons found no benefit for high-dose FA or levamisole (Lancet 2000;355:1588-1596). A non-randomised comparison suggested equal efficacy but less toxicity with the once-weekly schedule (Annals of Oncology 2000;11:947-955). With a median follow-up of 4.2 years, risk of death with CT vs control was 0.88 (95%CI 0.75-1.05; p=0.15) and recurrence 0.82 (0.70-0-97; p=0.02). Treatment efficacy did not differ significantly by stage, site or age but efficacy of the 4-weekly schedule was significantly (p=0.04) greater than once-weekly -a prior hypothesis. CONCLUSIONS: Chemotherapy produces a small (1% - 5%) survival benefit for stage B patients, sufficient to outweigh the inconvenience and cost for high-risk and younger patients. Longer follow-up and meta-analysis of all trials is needed to clarify the balance of benefits and disbenefits for older patients. No significant financial relationships to disclose.