Impact of intramural and extramural vascular invasion on stage II‐III colon cancer outcomes

BACKGROUND AND OBJECTIVES: Vascular invasion, in particular extramural venous invasion (EMVI), is a pathologic characteristic that has been extensively studied in rectal cancer but rarely in colon cancer. This study aims to evaluate its prognostic role in stage II-III colon cancer. METHODS: All stage II-III colon cancer patients who underwent surgery between 2004 and 2015 were reviewed. We compared patients without invasion, with intramural invasion only (IMVI), EMVI only, and both IMVI/EMVI (n = 923). RESULTS: EMVI was associated with other high-risk features, including T4, N+ disease, lymphatic, and perineural invasion (P < 0.001). EMVI+ patients had higher rates of locoregional and distant recurrence and subsequently disease-specific mortality (stage-II, odds ratio [OR] 3.64; P = 0.001; stage-III OR, 1.94; P = 0.009), whereas outcomes were comparable between IMVI and no vascular invasion (OR, 1.21; P = 0.764; OR, 1.28, P = 0.607, respectively). The adjusted HRs for EMVI+ patients on disease-free survival, and disease-specific survival were 2.07 ( P < 0.001) and 1.67 ( P = 0.027), respectively. Moreover, EMVI+ stage-II patients fared worse than EMVI- stage-III patients, even after adjusting for adjuvant chemotherapy. CONCLUSION: EMVI is a strong predictor for worse oncologic outcomes in stage II-III colon cancer patients, whereas IMVI is not. It is also associated with worse outcomes compared in patients with higher stage disease who are EMVI negative.