Meguid RA et al. (2008) Is there a difference in survival between right- versus left-sided colon cancers? Ann Surg Oncol 15: 2388–2394

The incidence of right-sided colon cancers has increased since the 1980s, while the incidence of left-sided colon cancers has decreased. Numerous hypotheses have been proposed to explain this phenomenon but whether right-sided and left-sided colon cancers have a different prognosis is still unclear.

Meguid et al. retrospectively analyzed data from the Surveillance, Epidemiology and End Results Program (SEER) to compare survival between patients with right-sided and left-sided colon cancers. A total of 77,978 patients who underwent surgical resection for a first primary adenocarcinoma of the colon were included in the study, of whom 57.1% had right-sided colon cancer and 42.9% had left-sided.

The median survival of all patients studied was 83 months. After diagnosis, patients with right-sided colon cancer had a significantly shorter survival time than those with left-sided colon cancer (78 versus 89 months, respectively). Survival for right-sided colon cancer was significantly shorter than for left-sided colon cancer at 5, 10 and 15 years, respectively (P <0.001 for all comparisons). Right-sided colon cancer was associated with an increased risk of mortality compared with left-sided colon cancer.

The authors conclude that patients with right-sided colon cancer have a worse prognosis than those with left-sided colon cancer, even after adjustment for American Joint Committee on Cancer stage, tumor grade, number of lymph nodes examined, year of diagnosis and patients' demographic variables. Further studies are needed to determine the cause of the observed difference in survival.