The effect of microsatellite instability on survival in non-metastatic right and left colon cancers

Background: Colon cancers are the most common cancers among gastrointestinal system cancers. Colorectal cancers, which you evaluate together with the rectum, are seen in the 3rd frequency in our country after breast and thyroid cancers in women, and after lung and prostate cancers in men. Some characteristic features have been shown in MSI positive patients. This confirmed is thought to be important in terms of patient survival, prognosis, and treatment. Aim: Evaluation of survival and prognosis in MSI positive or MSI negative patients according to tumor localization in patients with non-metastatic colon adenocarcinoma who were operated on in our hospital. Methods: Our study included 247 colon adenocarcinoma cases, whose mismatch repair protein expression was determined by the pathology report immunohistochemically. Patients were divided into 2 groups as right and left colon according to tumor localization. The effect of microsatellite instability in the right and left colon on survival was investigated. Results: 1-year survival was 93% and 3-year survival 85% in MSI patients, 1-year survival was 84% and 3-year survival was 73% in MSS patients at right colon cancer. While 1-year survival was 91% and 3-year survival was 80% in MSI patients, 1-year survival was 84% and 3-year survival was 76% in MSS patients at left colon cancer. However, no statistically significant difference was found in the findings. In addition, the 3-year survival rate of those who received adjuvant therapy was 100% in Stage 2 MSI-positive patients, while this rate was 84.6% in those who did not receive adjuvant therapy. Right and left colon patients could not be evaluated separately due to insufficient number of patients. Poor differentiation was seen in 36% of MSI patients and 6% of MSS patients. Findings were similar in the right and left colons. According to TNM staging, 63.2% of MSI patients were stage 2 and 48.8% of MSS patients were stage 3 Conciusion: In our study, it was determined that the presence of MSI did not have a statistically significant difference in survival in patients with right and left colon cancer. Compared to CNS patients, MSI patients were found to be at a lower stage. This rate was similar in right and left colon cancers