Recurrence-Free Survival Outcomes Based on Novel Classification Combining Lymphovascular Invasion, Perineural Invasion, and T4 Status in Stage II–III Colon Cancer

Background: T4 tumor, lymphovascular invasion (LVI) and perineural invasion (PNI) are regarded as one of risk factors and associated with poor outcomes in colorectal cancer. The relationship between these three combined risk factors and the prognosis for colon cancer is not yet clear. The purpose of this study was to evaluate the prognostic value of combining the risk factors T4 tumor, LVI, and PNI in stage II-III colon cancer. Methods: Between January 2011 and December 2019, we retrospectively reviewed the medical records of patients who underwent curative resection for stage II-III colon cancer at four Hallym University-affiliated hospitals. These patients are categorized into three groups based on T4, LVI and PNI: no-risk group (no risk factors), low-risk group (one risk factor), and high-risk group (two or more risk factors). Results: Of 1684 patients, the incidence of no-, low-, and high-risk group were 49.3%, 32.6%, 18.0%, respectively. The median follow-up period was 48.9 months, and the 5-year recurrence-free survival (RFS) rate decreased from 78.5% to 58.7% as the number of risk factors increased (P < 0.001). Cox's proportional hazard regression models showed that T4 (P < 0.001), LVI (P = 0.043), and PNI (P = 0.018) were independent prognostic factors for poor RFS. In subgroup analysis in stage II colon cancer, patients with one or more risk factors showed the better 5-year RFS rate when they received adjuvant chemotherapy than in those who did not (P < 0.001). Poor/mucinous differentiation, obstruction, and lymph-node positivity were independent predictors in the high risk group. Conclusion: The present study showed the histological combination of LVI, PNI, and T4 indicates a poor prognosis for RFS in patients with stage II-III colon cancer. Therefore, patients with one of these risk factors should be considered for chemotherapy and have close follow-up.