Background: Right-sided colon cancer (RC) is derived from the mid-gut, while left-sided colon cancer (LC) originates from the hindgut. LC has been associated with better survival compared to RC. The effect of primary tumor sidedness on colorectal cancer (CRC) survival rates has not been studied in VA hospitals.
Methods: Data from the National VA Cancer Cube Registry was studied. 65,940 cases of CRC were diagnosed between 2001 and 2015. ICD codes C18 to C20 were used to delineate patients with RC vs. LC. RC was defined as cancer from the cecum to the hepatic flexure, LC from the splenic flexure to the rectum with transverse cancer in between flexures. Local IRB approval was obtained.
Results: Of the total number of CRC, 30.3% were RC and 58.8% were LC. RC constituted 36.3% of cases in women and 30.1% of cases in men. RC was diagnosed after the age of 70 years in 51.8% of cases, compared with 38.5% of LC. LC constituted 56.0% of CRC in blacks, and 59.4% in whites. RC was more likely to be diagnosed at more advanced stage, with 60.84% of cases diagnosed at stage II-IV, compared to 51.82% of LC. Stage IV RC has worse one year survival as compared with LC (50.5% vs 42.2% surviving less than one year, respectively)
Conclusions: RC is associated with female gender, older age, poorer functional status, and more advanced stage at diagnosis. LC was associated with white race. Stage IV RC had worse one-year survival than LC colon cancer.
