Background: Tumors of the colon and rectum are one of the most common malignancies worldwide. However, its incidence was less in India compared to the developed countries. In the recent years, due to westernization, sedentary lifestyle and increased consumption of animal fats with less dietary fibre intake have increased the incidence in India in the past few decades. Family history and Microsatellite instability also predisposes the patient to Colo-rectal carcinoma. Many prognostic factors have been studied in Colo-rectal cancers and have been proved. However newer factors like macrophage infiltration in the tumor microenvironment have been studied. Many theories have been put forth to study these macrophages and their sub population M1 and M2. M1 macrophages are considered to be tumoricidal whereas M2 macrophages are considered to promote tumor growth by releasing growth factors and promoting angiogenesis. Hence, the study of these macrophage subpopulation M1 and M2 can help in assessing the prognosis in patients with Colo-rectal cancers. Aims & Objectives: 1. To determine the expression of CD68 and CD163 in Colorectal Cancer. 2. To correlate the expression of CD68 and CD163 with the histological grade and stage of the tumor. Materials and Methods: All Colorectal carcinoma specimens received in the Department of Pathology from R.L. Jalappa Hospital and Research Center attached to Sri Devaraj Urs Medical College, Tamaka, and Kolar from December 2016 to September 2018 and also the paraffin blocks taken from all cases of Colorectal cancer retrieved from Archives of Department of Pathology from the year January 2008 to November 2016 were included in the study. Data regarding the clinical details (Age, Sex, Histological grading) were collected. Hand E slides were reviewed for Histopathological types, grade and staging of the tumor. Immunohistochemistry for CD68 and CD163 (Biocare mouse antibody) was performed on all cases of Colorectal Carcinoma using appropriate positive and negative controls by peroxidase and anti peroxidase method. Results: A total of 62 cases were studied of which 39 were males and 23 were females. The most common site of tumor was Rectum followed by ascending colon. Majority of the tumors were less than 5 cms. The most common grade was moderately differentiated adenocarcinoma. Maximum number of cases were in Stage III, 23 cases (37.1%) Perineural invasion was seen in 2 cases and lymphovascular invasion was seen in 3 cases. Maximum number of cases (64.5%) were in lymphnode ratio less than <0.111. Expression of CD 68 was significantly correlating with site of the tumor, Size of the tumor, Grade, and lymphnode ratio. Expression of CD 163 was correlating with T stage, N stage, TNM stage, and Lymphnode ratio. Conclusion: CD 68 expression was associated with better prognostic factors such as smaller size of tumor, lesser grade and lesser lymphnode ratio(LNR) and CD 163 expression was associated with poorer prognostic factors such as higher T stage, Higher N stage, and higher values of lymphnode ratio (LNR). Hence, CD 69 and CD 163 can serve as a reliable prognostic marker in colo-rectal cancers.

Keywords: Colo-rectal cancer; Immunohistochemistry; Prognosis.