Prognostic impact of tumor location in stage IV colon cancer: a propensity score analysis in a multicenter study.

BACKGROUND

Right-sided colon cancer is considered to be biologically different from left-sided colon cancer; however, conflicting results have been reported regarding differences in prognosis. We aimed to clarify the prognostic impact of tumor location in stage IV colon cancer.

METHODS

Stage IV colon cancer treated from January 1997 to December 2007 (n = 2208) were retrospectively studied. Clinical and pathological features were compared between right-sided colon cancer (cecum, ascending, and transverse colon) and left-sided colon cancer (descending, sigmoid, and rectosigmoid colon). The impact of tumor location on cancer-specific survival (CSS) was analyzed in a multivariate analysis and propensity score analysis to mitigate the differences in background features.

RESULTS

Right-sided colon cancer was associated with older age, female sex, larger tumor size, poorly differentiated adenocarcinoma, mucinous adenocarcinoma, and signet-ring cell carcinoma, a more advanced state within stage IV disease, and a worse CSS. In the cohort matched by propensity scores for background clinicopathological features, tumor location in the right-sided colon was associated with a significantly worse CSS (hazard ratio 1.2, 95% confidence interval 1.1-1.4, p = 0.008) in patients treated with palliative primary tumor resection, but not in those treated with R0 resection or no resection.

CONCLUSION

Right-sided colon cancer were diagnosed at a more advanced state within stage IV disease and showed a significantly worse prognosis than left-sided colon cancer, suggesting that stage IV right-sided colon cancer is oncologically more aggressive than left-sided colon cancer.