Extramural vascular invasion is an adverse prognostic indicator of survival in patients with colorectal cancer.

Background/aims  Extramural vascular invasion (EVI) in colorectal cancer is reported to be a stage-independent adverse prognostic factor, and is a core item in the Royal College of Pathologists minimum data set for colorectal cancer histopathology reporting. The detection of EVI is also highly variable amongst pathologists. Our aims were to analyse both the frequency of EVI in colorectal cancer resections, and the effect of EVI on survival, in patients operated on over a 5-year period. Method  A retrospective analysis of patients having potentially curative surgery for colorectal cancer between January 1999 and December 2004. Results  Over 5 years, 378 patients underwent a potentially curative resection. One-hundred seven (28.3%) cancers exhibited EVI, of which 104 (97%) were T3 and T4 tumours. Survival curves with and without EVI, unadjusted for nodal status and T stage, were significantly different (P = 0.0001) with 5-year survivals of 52% and 73% respectively. Survival curves for T3 and T4 tumours stratified with and without EVI also showed significantly different survival distributions (P = 0.007). A significant difference in frequency of EVI year on year was seen (P < 0.001), ranging from 8.5% to 46.7%, whereas the number of T3 and T4 tumours in each year was not significantly different (P = 0.677). Conclusions  EVI is an adverse prognostic indicator for survival in patients undergoing potentially curative resection of colorectal cancer, and the routine requirement of EVI in colorectal cancer histopathology reporting is justified. Optimal specimen preparation, meticulous histopathological analysis and regular auditing of EVI detection rates are essential for the accurate staging of colorectal cancer.