[Relationship between venous invasion and hematogenous metastasis in the colorectal cancer patients]

We investigated the correlation between venous invasion and hematogenous metastasis. In thirteen patients with colorectal carcinoma, depth of invasion (ss.s or a1.a2) was the same. Four cases had hepatic metastasis at operation (group A), 3 cases were identified with hematogenous recurrence after operation (group B), and 6 cases were disease free over 10 years after operation (group C). Specimens were all step-sectioned and serial sections were stained both with HE and EM. Results were as follows. 1. Venous invasion was found in all cases and average rates of venous invasion (ARVI) of groups A and B were higher than that of group C (A; 7.8%, B; 6.3%, C; 2.1%, p less than 0.05). 2. In ss.s layer, ARVI of group A and B were higher than that of group C (A; 6.1%, B; 6.2%, C; 1.5%, p less than 0.05). 3. Rates of venous invasion to larger veins (diameter greater than 200 microns) were higher in group A than in others (A; 53.5%, B; 25.6%, C; 7.9%, p less than 0.05), and those to the middle-sized veins (diameter; 50-200 microns) were higher in group B than in others. These facts suggest that cancer invasion to the veins located in ss.s (a1.a2) layer or ranged in diameter over 200 microns relates to hematogenous metastasis.