Prognostic impact of tumour laterality in early-stage colon cancer: A population-based study.

Abstract

e15148 Background: Recent data has suggested that disease biology and outcome of colon cancer may differ between right-sided and left-sided tumours. Here we explore differences in laterality based on disease characteristics and outcomes in a population-based cohort of early-stage colon cancer. Methods: Electronic records of treatment were linked to the Ontario Cancer Registry to identify all patients with colon cancer in 2002-2008. The study population included a 25% random sample of all patients with resected stage 0-III disease. Right-sided colon cancer was defined as any tumor arising in the cecum, ascending colon, hepatic flexure or transverse colon. Left-sided colon cancer was defined as any tumor arising from the splenic flexure, descending colon, sigmoid colon or rectosigmoid colon. Log binomial regression was used to identify factors associated with laterality. Cox models were used to explore the association between laterality and overall (OS) and cancer-specific (CSS) survival. Results: Among the study cohort (n = 6391) median age was 72 and 52% (3307/6391) had right-sided disease. Stage distribution was 2% (98/6391) stage 0, 17% (1091/6391) stage I, 38% (2446/6391) stage II, and 43% (2756/6391) stage III. Patients with right-sided colon cancer were more likely to be older (p < 0.001), female (p < 0.001) and have greater co-morbidity (p = 0.001). Right-sided cancer was more likely to be T4 (19% vs 16%, p = 0.001) and poorly differentiated (21% vs 10%, p < 0.001) but less likely to be node positive (42% vs 45%, p = 0.029) compared to left-sided disease. In adjusted analyses there was no difference in long-term survival for right-sided compared to left-sided colon cancer: OS HR 1.00 (95%CI, 0.92-1.08); CSS HR 1.00 (0.91-1.10). These results were consistent when the survival analyses were restricted to stage III disease: OS HR 1.03 (95%CI 0.93-1.14); CSS HR 1.10 (0.97-1.24). Conclusions: In this population-based cohort of early-stage resected colon cancer disease laterality was not associated with long-term survival.