Clinicopathological characteristics of microsatellite stable and instable colorectal cancers; investigation of preoperative hematological parameters and their relationship with systemic inflammatory scoring systems

Background: According to the data of the Turkish Ministry of Health, colorectal cancers are the third most common after lung and prostate cancers in men, and third after breast and thyroid cancers in women. Determination of microsatellite instability (MSI) status in sporadic colon cancers is important for the treatment of the disease. Aim: Our aim is to evaluate the relationship of certain clinical and pathological features and preoperative hematological parameters and systemic inflammatory scoring systems with microsatellite instability in colon cancer patients. Methods: Our study included 453 colorectal adenocarcinoma cases, whose mismatch repair protein expression was determined by the pathology report immunohistochemically. The patients were divided into two groups as microsatellite stable and instable. In this retrospective study, pathological data such as tumor size, tumor invasion depth, lymphovascular invasion, perineural invasion, tumor differentiation, tumor clinical stage, number of lymph nodes removed in the operation, number of metastatic lymph nodes, tumor localization, and hematological data such as preoperative hemoglobin, neutrophil, lymphocyte, monocytes, platelet counts as well as survival and follow-up durations were compared between groups. Results: A significant difference was found in the distribution of TNM stages according to MSI and MSS groups (p=0.007). While 37.3% of MSS patients were stage 3, the majority of MSI patients were stage 2 (57.1%). The number of dissected lymph nodes was higher in the MSI group (p<0.001). The probability of metastasis in the lymph node was higher in the MSS group (p=0.018). Evaluation of grade, which is a poor prognostic criterion, between the groups showed that high grade was more frequent in the MSI group with a rate of 25% versus 7.1%. In this study, it was revealed that there was a statistically significant difference between microsatellite stable and instable groups in NLR, PLR, LMR ratios (p<0.05). While NLR and PLR rates were higher in the microsatellite instable group, LMR was statistically significantly higher in the microsatellite stable group. Conclusion: It was found that microsatellite instable cases had a lower TNM stage, more lymph node dissection was performed in these cases, and these cases had less lymph node metastasis. In our study, a cut-off value was determined for NLR, PLR and LMR ratios, and patients above these values were found to be microsatellite unstable with high sensitivity and specificity. As a result of this study, in which we pointed out the possibility of microsatellite instability with the data we easily obtained from the complete blood count, patients above the cut-off value can be referred for further investigations. Keywords: Colorectal cancer, Microsatellite Instability, Systemic Inflammatory Scoring Systems