Microsatellite-unstable colorectal cancer in elderly patients: clinical features and the role of immunodeficiency

Background. Tumors demonstrating the phenomenon of microsatellite instability (MSI) represent a special category of colorectal cancer (CRC). Such neoplasms account for up to 20 % of CRC and are characterized by specific molecular and clinical manifestations, including high immunogenicity and sensitivity to immunotherapy. MSI phenotype occurs in two different groups of patients: young individuals with Lynch syndrome and patients older than 70 years with non-hereditary CRC. We assume that the development of sporadic MSI-positive tumors in elderly patients may be associated with age-dependent decrease in immune defense. The aim of the study was to investigate clinical and morphological characteristics in elderly patients with MSI-positive colorectal cancer. Material and Methods. MSI status and mutations in the BRAF gene were tested in a group of 384 CRC patients older than 65 years by PCR-based techniques. A comparative analysis of clinico-pathological features was further conducted in the groups of 23 MSI-positive and 34 MSI-negative CRC cases. Results. MSI-positive phenotype was associated with the proximal tumor location, low degree of differentiation and the presence of the mucinous component in the tumor (p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }