This study aimed to elucidate the prognostic implications of extramural venous invasion (EMVI) in colorectal cancer (CRC) through a meta-analysis. Eighteen eligible studies were included in this meta-analysis. Data on the prevalence of EMVI and the correlation between EMVI and survival were collected from these studies. In addition, a subgroup analysis was conducted based on tumor location and evaluation methods. The estimated prevalence of EMVI was 28.3% (95% confidence interval [CI] = 23.1% to 34.0%) in patients with CRC. The estimated prevalence of EMVI in patients with colon cancer and rectal cancer was 23.0% (95% CI = 17.6% to 29.6%) and 35.7% (95% CI = 22.3% to 51.6%), respectively. Based on the evaluation method, the estimated prevalence of EMVI were 28.3% (95% CI = 23.2% to 34.1%) and 27.3% (95% CI = 8.4% to 60.6%) in pathologic and radiologic examinations, respectively. The correlation of EMVI with worse overall and disease-free survival rates was significant (hazard ratio = 1.773, 95% CI = 1.483-2.120, and hazard ratio = 2.059, 95% CI = 1.683-2.520, respectively). However, in the subgroup analysis with radiologic examination, there was no significant difference in survival rates between patients with and without EMVI. Our study showed that EMVI was frequently detected in 28.3% of patients with CRC and was correlated to worse survival. The detection of EMVI can be useful for predicting the prognosis of patients with CRC.
Keywords: colorectal cancer; extramural venous invasion; meta-analysis; prognosis; venous invasion.