Microsatellite instability in gastric carcinomas in Kano, Nigeria

Abstract

Background and Objectives: Gastric carcinoma, though relatively less prevalent in most parts of Africa and Nigeria, usually presents at an advanced stage in most of our patients. This makes the elucidation of clinical and molecular factors relating to prognosis an important avenue to explore. Gastric carcinomas exhibiting microsatellite instability (MSI) are said to have better prognosis, but there has been no study in Northern Nigeria. We, therefore, undertook this study to evaluate the proportion of MSI gastric carcinoma in our center. Methodology: This retrospective 5-year study was done on 48 histologically diagnosed gastric carcinomas to evaluate the immunohistochemical expression of mismatch repair DNA proteins: MLH1 and MSH2. Results: Forty-eight gastric cancer (GC) biopsies fulfilled the study criteria. They were from patients aged 23–80 years, with a mean of 52.1 years (standard deviation [SD] ±12.79) and male to female ratio = 3.4:1. Twenty cases (42%) had MSI, with a mean age of 51.7 years (SD ± 12.75; P = 0.67). The remaining 28 cases were microsatellite stable (MSS), with a mean age of 53.3 years (SD ± 12.92). Male preponderance was more marked in the MSS group (6:1) than in the MSI group (2.3:1). Intestinal carcinoma was by far the most common histologic type in both MSI (75%) and MSS (70%) groups. Conclusion: Forty-two percent of gastric carcinomas were harboring MSI. Although our sample size was small, it nonetheless provided useful insight and baseline data for MSI gastric carcinoma in our center. MSI GC appears to be more common in our center than an earlier Southern Nigerian study. This is consistent with the widely differing proportion of MSI gastric carcinoma across the globe, sometimes within the same country. Further studies are therefore required to make sense of this seemingly conflicting data.