The prognostic impact of intramural invasion in patients undergoing surgery for non-metastatic colon cancer.

Abstract

e15516 Background: The invasion of extramural veins is an independent predictor of poor outcome in colorectal cancer whereas the significance of intramural component of venous as well as lymphatic and perineural invasion is less clear. We aimed to search the prognostic impact of these invasion patterns and their association with various clinicopathological variables. Methods: All patients undergone surgery for colon cancer between December 2014 and December 2020 were analyzed retrospectively and patients with stage II and III disease were enrolled. The patients were divided into four categories as no invasion, intramural invasion only, extramural invasion only or both (intramural and extramural) for vascular invasion (VI), lymphatic invasion (LI) and perineural invasion (PNI). 5-year disease-free (DFS) and overall-survival (OS) were the primary outcomes. Results: 626 patients were included (47.1% stage II patients). There was no significant difference between the presence of ‘intramural only’ venous (DFS, 87.2 vs 88.4% p = 0.84; OS, 88.3 vs 90.7% p = 0.90), lymphatic (DFS, 89.5 vs 85.1%, p = 0.13; OS, 89.5 vs 89.4%, p = 0.9) and perineural invasion (DFS, 89.1 vs 80.9%, p = 0.26; OS, 90.6 vs 84.8%, p = 0.12) compared to ‘no invasion’ in terms of DFS and OS. Invasion of both intramural and extramural compartments for each of these parameters demonstrated poor survival. Presence of exclusively extramural venous and perineural invasion without intramural invasion had adverse effect on DFS (87.2 vs 78.7%, p = 0.036, 89.1 vs 80.9%, p = 0.044, respectively) but not OS (88.3 vs 89.3%, p = 0.78, 90.6 vs 83.8%, p = 0.215, respectively). Tumor sidedness did not have impact on the depth and rate of lymphatic invasion however right-sided and dMMR tumors exhibited less venous and perineural invasion (24.7 vs 33.9% p = 0.007; 34.5 vs 41.5% p = 0.034 and 13.5 vs 33.5% p < 0.001; 25 vs 41.4% p = 0.004, respectively). The ratio of stage III patients with venous, lymphatic and perineural invasion was consistently higher when compared with stage II patients (for LI 69.8 vs 39.7% vs p < 0.001; for VI 36.9 vs 22.7% p < 0.001; for PNI 51.4 vs 24.4% p < 0.001). Low grade tumors exhibited less LI and PNI when compared with high grade tumors (for LI 53.2 vs. 71.3% p = 0.004, for PNI 37.1 vs. 48.3% p = 0.031) however there was no significant difference for venous invasion rates among two groups. Conclusions: Presence of merely intramural component of invasion may not be considered a synonym for lymphovascular invasion which is supposed to be a high-risk factor for systemic recurrence.