Background: Extramural venous invasion is an independent predictor of poor outcome in colorectal cancer, whereas the significance of the intramural component of venous and lymphatic and perineural invasion is unclear.
Aims: To evaluate the prognostic impact of intramural components for venous, lymphatic, and perineural invasions and the relation of these invasion patterns with clinicopathological features in patients with colon cancer.
Study design: A retrospective cross-sectional study.
Methods: The analysis included 626 patients with colon cancer in stages II and III. All patients were divided into four categories (no invasion, intramural invasion only, extramural invasion only, or both intramural and extramural invasions) for vascular invasion, lymphatic invasion and perineural invasion. The primary outcomes were 5-year disease-free and overall survival.
Results: Right-sided (for vascular invasion, 24.7% vs. 33.9%, p = 0.007; for perineural invasion, 34.5% vs. 41.5%, p = 0.034) and dMMR tumors (for vascular invasion, 13.5% vs. 33.5, p < 0.001; for perineural invasion, 25% vs. 41.4%, p = 0.004) exhibited less venous and perineural invasion. Compared with no invasion, presence of intramural invasion only, did not exert any effect on disease-free or overall survival for vascular invasion, lymphatic invasion, and perineural invasion. Multivariate analyses revealed that the presence of both intramural and extramural invasion was independently associated with poor disease-free and overall survival for venous (hazard ratios: 2.39, p = 0.001; hazard ratios: 2.46, p = 0.001), lymphatic (hazard ratios: 2.456, p < 0.001; hazard ratios: 2.13, p = 0.02) and perineural invasion (hazard ratios: 2.99, p < 0.001; hazard ratios: 2.68, p < 0.001), respectively.
Conclusion: Our data strongly advocates the importance of reporting intramural and extramural components of invasion since the presence of intramural invasion alone may not be considered as a high-risk factor for systemic recurrence.