Background: Colorectal adenocarcinoma is a malignancy of the large intestine (colon and rectum) of epithelial origin, ranks third in the world, and the second leading cause of cancer death. The prognosis can be assessed based on the reaction of the tumor microenvironment that plays a role in the stage of cancer development. Immunohistochemical examination of Fibroblast Activation Protein (FAP) as well as an assessment of grading and how the ratio between the extent of tumor and stroma (Tumor-Stroma Ratio) has recently been one of the prognostic predictors of colorectal adenocarcinoma. Objective: To analyze the relationship of immunohistochemical expression of Fibroblast Activation Protein (FAP) with histopathological grading and Tumor-Stroma Ratio (TSR) in colorectal adenocarcinoma. Materials and Methods: 32 samples in the form of histopathological slides from surgical tissue with a diagnosis of colorectal adenocarcinoma, reviewed slides and assessed for grading and TSR scores, then performed immunohistochemical staining of Fibroblast Activation Protein (FAP) and assessed the expression, then analyzed for correlation between variables using the Somers'd correlation test. Results: The most histopathological grading distribution was low grade, the highest TSR was TSR-High, and the highest FAP expression found was strong expression. Based on the Somer's d correlation test, it was found that there was a significant correlation between FAP expression and grading (p=0.037) and there was no significant correlation between FAP expression and TSR (p=0.244). Conclusion: The tumor microenvironment is one of the prognostic predictor factors in colorectal adenocarcinoma patients, should be reported in the routine pathology report and further investigated how the stromal component and the role of FAP expression to open the possibility of other targeted therapies. Keywords: Fibroblast Activation Protein, Tumor-Stroma Ratio, colorectal prognosis

Fibroblast Activation Protein

Tumor-Stroma Ratio

Colorectal prognosis