Mgmt immunohistochemical expression in colorectal carcinoma and its correlation with tumor progression

BACKGROUND: There is an urgent need to identify predictive features and markers for progression and treatment of colorectal carcinoma (CRC). AIM: This study aimed to assess O6-methylguanine DNA methyltransferase (MGMT) expression in CRC and to correlate with the clinico-pathological aspects of the tumor, also to evaluate the relationship between different histopathologic parameters and tumor progression. MATERIALS AND METHODS: The study was carried on 70 colectomy using formalin fixed paraffin embedded tumor tissue not subjected to chemo-radiotherapy nor with missing data. Specimens were collected from the Department of Pathology of Kasr El-Aini Hospital, Faculty of Medicine, Cairo University, during the period between (March-2017 and May-2018). Immunohistochemistry was used to detect MGMT expression and clinico-pathologic aspects as well as to assess tumor budding, type of desmoplastic reaction (DR), inflammatory lymphocytic milieu, pattern of invasive front and necrosis, and then correlated with MGMT expression and tumor progression, using parametric and non-parametric statistical methods. RESULTS: MGMT loss of expression was detected in 42.9% of CRC cases. MGMT expression status was significantly correlated with tumor stage and metastatic status (p < 0.05), while it was not correlated with other clinico-pathologic features, (p > 0.05). DR, tumor budding, stromal tumor infiltrating lymphocytes (TIL-S), and necrosis were correlated with tumor stage (p < 0.05). DR correlated with tumor budding (p < 0.05). Both types of TIL and Crohn’s-like lymphoid reaction showed a mutual correlation (p < 0.05). CONCLUSION: MGMT high expression and histopathologic parameters as DR, tumor budding, inflammatory lymphocytic milieu, and necrosis could be correlated with CRC progression.