Adjuvant therapy for stage III colon cancer after complete resection. Provincial Gastrointestinal Disease Site Group.

Guideline questions: Should patients with resected stage III colon cancer receive adjuvant therapy? If so, which therapy should be recommended?

Objective: To make recommendations regarding the use of adjuvant therapy in the treatment of resected stage III colon cancer.

Outcomes: Overall survival is the primary outcome of interest. Secondary outcomes are disease-free survival and adverse effects of the treatment regimens.

Perspective (values): Evidence was selected and reviewed by 4 members of the Gastrointestinal Disease Site Group (GI DSG) of the Ontario Cancer Treatment Practice Guidelines Initiative. Earlier drafts of the guideline were reviewed, discussed and approved by the GI DSG, which comprises medical and radiation oncologists, surgeons and epidemiologists. Community representatives did not participate in the development of this guideline but will participate in future guidelines development.

Quality of evidence: There are 3 meta-analyses, 33 published randomized controlled trials (RCTs) and 1 consensus statement. The GI DSG pooled data from 10 of the 33 RCTs that allowed for such an analysis.

Benefits: Two of 3 RCTs reported improved survival rates with 5-fluorouracil (5-FU) plus semustine or mitomycin C (MMC) compared with no treatment (observation) after surgical resection. Three trials reported a benefit in both overall and disease-free survival with 5-FU plus levamisole compared with observation after surgery. In 2 trials, levamisole alone did not produce a survival benefit compared with observation. One trial reported improved disease-free, but not overall, survival rates with oral HCFU (1-hexylcarbamoyl-5-fluorouracil) compared with observation. In 3 trials of 5-FU plus leucovorin, disease-free and overall survival rates were improved compared with observation. Nine trials compared portal vein infusion (PVI) of 5-FU with observation after surgery. In 2 of the trials, for which data were available for stage III patients only, improved overall survival was reported. There was a trend in all studies favouring PVI. One trial reported a survival benefit for stage III and IV patients who received oral HCFU maintenance therapy for 1 year compared with no maintenance therapy. In a trial comparing MMC plus oral HCFU with MMC alone, a survival benefit was reported in the combined treatment group; however, the stages of cancer were unevenly distributed among the treatment groups. Only 1 study tested monoclonal antibody; a benefit was reported for both overall and disease-free survival. A meta-analysis of 10 trials comparing adjuvant therapy with observation in patients with stage III disease detected a significant reduction in the odds ratio (OR) for death (OR 0.69; 95% confidence interval [CI] 0.57 to 0.85), with an absolute improvement in survival of 4% to 13%. When trials were separated according to the type of treatment given, the significant ORs were for 5-FU plus either levamisole (OR 0.61; 95% CI 0.46 to 0.80) or leucovorin (OR 0.51; 95% CI 0.36 to 0.73). Three recently reported trials comparing various combinations of 5-FU plus leucovorin, with or without levamisole, showed similar improvements in disease-free and overall survival.