Role of immunohistochemistry in molecular classification, prognosis, and survival of colorectal cancer patients

The aim of this study is to describe the role of IHC in molecular classification, prognosis and survival of CRC patients in Upper Egypt. This is a retrospective cross-sectional multicenter study conducted on 67 specimens of colon adenocarcinoma from the pathology laboratory of Qena University Hospital, South Valley University, and the oncological pathology department at South Egypt Cancer Institute at Assiut University. The most prevalent molecular subtype was epithelial-type carcinoma (CMS 1, 2, 3) (70.1%) followed by hybrid-type carcinoma (CMS 4) (25.4%) and the least frequent subtype was mesenchymal carcinoma (4.5%). There were statistically significant associations between molecular subtypes and age (p-value<0.001), pathological T stage (p=0.045); tumor location (p=0.038); nodal status (p=0.005); deposits (p=0.013); tumor infiltrating lymphocytes (p=0.033) and perineural invasion (p=0.008). Patients with epithelial-type carcinoma had the best overall survival rate and disease-free survival rate, there was a statistically significant association between molecular subtypes and disease-free survival of colorectal cancer (p= 0.023). The most significant predictor of poor survival was metastasis either nodal or in distant organs, with a p-value <0.001 and Hazard Ratio =35.926, followed by N2-stage (p-value =0.027, HR =2.771). Liver metastasis was the most prevalent in (34.3%) of cases followed by peritoneal deposits, lung metastasis in (12.7 % and 4.8%), respectively and (95.1%) of cases received postoperative chemotherapy. There were highly statistically significant association between vimentin and age (p <0.001). The availability of immunohistochemical markers for both diagnostic and predictive/prognostic purposes is anticipated to establish a role for practicing pathologists who might utilize these skills in their daily practice with CRC patients.