Odeny TA, et al. - Researchers examined the link between tumor location, perioperative carcinoembryonic antigen (CEA) ratio, and 5-year survival among 111 patients who underwent resection for colorectal cancer (CRC) at KUMC. They excluded patients without pre- or post-operative CEA data. They could calculate a CEA ratio (post-op/pre-op CEA) for 62 patients and these were categorized as either high ( ≥ 0.5) or low ( < 0.5) ratio. Study participants had median age of 61 years, 54% were male, 31% were smokers, 74% had left-sided tumors, median pre-operative CEA was 3.3, and 60% had CEA ratio ≥ 0.5. In patients with left-sided vs right-sided tumors, the observed overall survival (OS) rates were 89.1% and 81.3%, respectively. In patients with high vs low CEA ratios, the observed OS rates were 83.8% and 92.0%, respectively. After adjusting for smoking status and tumor stage in multivariate analysis, both tumor location and perioperative CEA ratio had no significant relation to OS. Findings revealed no difference in OS between left vs right-sided tumors. Tumor location remarkably altered the link between perioperative CEA ratio and OS.