No abstract

Background: Right-and left-sided colon cancers are considered two distinct entities, with differences in embryological origin, clinical presentation and tumor biology. Although unclear whether these differences have meaningful impact in mortality, right colon location is many times associated with a worse prognosis. Some studies, however, have suggested that right colon location in stage II disease is associated with better overall survival, in contrast with the more advanced stages. The aim of this study is to assess the differences between primary tumor location in terms of disease free survival (DFS) and overall survival (OS). Methods: We identified all patients with AJCC stage II primary adenocarcinoma of the colon diagnosed from 2008 to 2013 in three hospitals in the Greater Lisbon Area, who underwent surgery for curative intent. Disease free survival (DFS) and overall survival (OS) were examined using the Kaplan-Meier survival analysis and Cox proportional hazards regression. Results: Among the 652 patients identified, 49% had right-sided colon cancer (RCC). There was no difference in age or sex demographics between RCC and left-sided colon cancer (LCC). Regarding the high-risk factors, grade 3 tumors were more common in RCC (p-value¼0.040); less than 12 removed lymph nodes and the presence of occlusion were more common in LCC (p-value¼0.005 and p-value¼0.006, respectively). No statistically significant difference was observed between RCC and LCC patients in disease free survival (HR 1.016 95%CI 0.615,1.679, p-value¼0.949) or overall survival (HR 0.980 95%CI 0.588,1.634 p-value¼0.938). Adjusting for sex, age group, chemotherapy and high risk features, there were still no differences observed between RCC and LCC, both in terms of DFS (HR 1.127 95%CI 0.680,1.868,) and OS (HR 1.086 95%CI 0.647, 1.822, p-value¼0.754). Conclusions: These findings demonstrate that, in stage II disease, there was no overall difference in DFS and OS between right-and left-sided colon cancers. Although there has been an increasing interest in determining the prognostic value of sideness in colon cancer, this may be of lesser importance in earlier stages.