EMVI as an independent predictor of recurrence and the role of chemotherapy in N0 colonic adenocarcinoma: retrospective Cox regression analysis (2015-2022).

[PURPOSE] Extramural venous invasion (EMVI) is a high-risk pathological feature in colorectal cancer, yet its role in guiding adjuvant chemotherapy in node-negative colon cancer remains uncertain. This study evaluates EMVI as a predictor of recurrence in patients undergoing colon cancer resection and investigates whether adjuvant chemotherapy affects recurrence in node-negative, EMVI-positive (N0/EMVI +) patients.

[METHODS] A retrospective cohort study was conducted on adults undergoing surgery for colon cancer at a single UK cancer centre between 2015 and 2022. Patients with rectal tumours or metastatic disease at presentation were excluded. Cox proportional hazards models were used to assess predictors of recurrence. Kaplan-Meier survival curves were generated to visualise recurrence-free survival (RFS) stratified by EMVI and chemotherapy status.

[RESULTS] Among 675 patients, EMVI was present in 361 (53%). EMVI was independently associated with increased recurrence (HR: 1.80, 95% CI: 1.14-2.84, p=0.011). In the N0/EMVI+ subgroup (n=124), chemotherapy was not significantly associated with reduced recurrence: partial chemotherapy (HR: 1.36, 95% CI: 0.30-6.20, p=0.69), full chemotherapy (HR: 1.53, 95% CI: 0.46-5.12, p=0.49). Kaplan-Meier analysis revealed five-year RFS of 80.9% for no chemotherapy, 60.6% for partial chemotherapy, and 41.6% for full chemotherapy (p=0.69). Survival differences were not statistically significant.

[CONCLUSION] EMVI is a predictor of recurrence in patients undergoing surgery for colon cancer. However, in node-negative patients with EMVI, chemotherapy was not significantly associated with improved recurrence-free survival. These findings highlight the need for larger, prospective studies to better define the role of EMVI in guiding adjuvant therapy in stage II colon cancer.