Lymph Node Evaluation and Survival After Curative Resection of Colon Cancer: Systematic Review

BACKGROUND: Adequate lymph node evaluation for cancer involvement is important for prognosis and treatment of patients with colon cancer. The number of lymph nodes evaluated may be a measure of quality in colon cancer care and appears to be inadequate in most patients treated for colon cancer. We performed a systematic review of the evidence for the association between lymph node evaluation and oncologic outcomes in patients with colon cancer. METHODS: Medline, Scopus, Cochrane, and the National Guidelines Clearinghouse databases were searched from January 1, 1990, through June 30, 2006, for studies in which survival data as a function of number of lymph nodes evaluated were available. These studies were evaluated for methodologic quality, design, and data source. A total of 61,371 patients were included. RESULTS: Seventeen studies from nine countries were eligible for systematic review, including two secondary analyses of multicenter randomized trials of adjuvant chemotherapy for colon cancer, five population-based observational studies, and 10 single-institution retrospective cohort studies. Despite heterogeneity in methodology and differences in threshold numbers of lymph nodes evaluated (range = 6-40 lymph nodes), 16 of 17 studies reported that increased survival of patients with stage II colon cancer was associated with increased numbers of lymph nodes evaluated. Four of six studies with data from stage III patients also reported a positive association with survival among patients with stage III colon cancer. CONCLUSIONS: The number of lymph nodes evaluated after surgical resection was positively associated with survival of patients with stage II and stage III colon cancer. These results support consideration of the number of lymph nodes evaluated as a measure of the quality of colon cancer care.