The prognostic value of signet ring cell histology in stage I/II colon cancer-a population-based, propensity score-matched analysis

Previous research associated signet ring cell histology in colon cancer patients with poor survival outcomes. The aim of this study was to analyze the prognostic significance of signet ring cell histology on overall and cancer-specific survival in patients with localized colon cancer. Stage I and II colon cancer patients treated with surgical resection between 2004 and 2015 were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Overall survival (OS) and cancer-specific survival (CSS) were assessed using risk-adjusted Cox proportional hazards regression models and propensity score methods. Eighty-eight thousand nine hundred fifty-eight stage I-II colon cancer patients were identified. Overall, 446 (0.5%) showed signet ring cell histology. In unadjusted analyses, the 5-year OS and CSS rates of patients with signet ring cell histology were 65.8 and 83.1%, respectively, compared with 74.3 and 88.7% in patients with non-signet ring cell adenocarcinoma (p values: OS, p < 0.001; CSS, p < 0.001). Neither in risk-adjusted Cox proportional hazard regression analysis (OS: hazard ratio (HR), 0.96 (95% CI, 0.82-1.12%) p = 0.616; CSS: HR, 1.01 (95% CI, 0.79-1.28%) p = 0.946) nor with propensity score matching (OS: HR, 0.96 (95% CI, 0.82-1.14%) p = 0.669 and CSS: HR: 1.09 (95% CI: 0.84-1.40%) p = 0.529), a survival disadvantage was found for signet ring cell histology. This is the first propensity score-adjusted population-based investigation on exclusively stage I and II colon cancer patients providing compelling evidence that signet ring cell histology does not negatively impact survival in stage I and II colon cancer after risk-adjusting for known prognostic factors. Therefore, standard treatment strategies can be applied in these patients.