Evaluations of vascular incasion, perineural invasion and serosal involvement in pathology slides of colorectal cancer

Background: Colorectal cancer (CRC) is one important cause of mortality in the world. In the common staging systems of CRC, many biological behaviors of the tumor that determine the prognosis are not defined. Risk stratification is becoming increasingly important in low-stage CRC, because these patients do not undergo adjuvant therapy unless poor prognostic factors such as vascular invasion (VI), perineural invasion (PI) and serosal involvement (SI) are present. Accurate evaluation of these factors in CRC specimens is still challenging. Methods: In this study, we evaluated the detection rate of VI, PI and SI in 180 patients of CRC who underwent surgical resection based on basic pathology reports, review of hematoxylin and eosin (H&E) slides with considering morphologic clues such as “protruding tongue” and “orphan artery” signs, and elastin stain for detection of VI. In addition, the stage of the disease, pT stage, tumor location, tumor type and grade were categorized, separately. We used the Fisher’s exact test for comparing variables between the two groups. P