Predominance of younger age, advanced stage, poorly-differentiated and mucinous histology in Israeli Arab patients with colorectal cancer

Background: Colorectal cancer (CRC) incidence in the Israeli population is higher in the Jewish population than among Arabs. Materials and Methods: To determine the differences in demographic, clinical, histopathological and molecular characteristics of CRC between these two ethnic groups, 125 Arab patients treated at 3 community hospitals over a 20-year period were compared to a group of 208 consecutive Jewish patients. The mutator (replication error-positive [RER]) phenotype was detected by immunohistochemical evaluation of hMLH1 and hMSH2 protein expression in tumor tissue. Results: The Arab patients were younger than the Jewish patients with a higher percentage of poorly-differentiated and mucinous cancers and a higher percentage of advanced stage cancers (Dukes' C+D) at presentation. The mutator phenotype was detected at similar rates in both ethnic groups. Conclusion: Our study demonstrated that CRC patients from two major ethnic populations in Israel, Arabs and Jews, differed in terms of the prevalence of the disease, pathological features and age at presentation, but not in frequency of mismatch-repair-positive cancers.