Colorectal cancer in Iran: Immunohistochemical profiles of four mismatch repair proteins

Abstract

Purpose: The aim of the present study was to determine the profile of mismatch repair (MMR) defects in Iranian colorectal cancer patients by using immunohistochemical staining for products of four MMR genes: MLH1, MSH2, PMS2, and MSH6. Methods: Tissue samples of 343 patients were immunostained for MLH1, MSH2, PMS2, and MSH6. Clinical and family history and survival data were compared between normal and abnormal staining patterns. Results: Fourteen percent of the patients had abnormal nuclear staining for MMR proteins. MLH1 was absent in four, MLH1/PMS2 in 15, PMS2 in five, MSH2 in 12, and MSH2/MSH6 in 12 patients. These tumors were more proximal, had a nonsignificant better survival, and were more associated with positive family history. Estimation of this study of prevalence of hereditary nonpolyposis colorectal cancer in Iran was 5.5% of the total colorectal cancers. Conclusions: Along with the recommendations of the National Institute of Cancer, we recommend immunohistochemistry staining for MLH1, MSH2, PMS2, and MSH6 for determining the eligibility of patients for mutation analysis of MMR genes. © 2009 Springer-Verlag.