Неоадъювантная химиоиммунотерапия у пациентов раком желудка с микросателлитной нестабильностью

Introduction. Perioperative chemotherapy is the standard treatment for patients with locally advanced resectable gastric cancer. The prognostic relevance of MSI status in patients undergoing neoadjuvant chemotherapy remains unclear. Aim. To study the prognostic significance of MSI in gastric cancer patients undergoing perioperative CT. Materials and methods. The study included 173 patients with locally advanced gastric cancer who received perioperative therapy at the N.N. Blokhin National Medical Research Center of Oncology. All patients underwent PCR testing for MSI-H in 5 markers (BAT25, BAT26, NR21, NR24, NR27). Tumor regression grades (TRG) were evaluated according to the Mandard tumour regression score, including disease-free survival (DFS) and overall survival (OS). Results. 17 (9.82 %) cases presented MSI-H. High TRG was detected in 15,17 % of patients with MSS status, 0 of 12 patients with MSI who received FLOT or FOLFIRINOX and 3 of 5 patients who received immunochemotherapy. The 6-month DFS in patients with MSS was 93 % versus 58 % in MSI-H patients who received CT and 100 % in patients from the immunochemotherapy group (p = 0.034). Conclusion. Our data show that the results of modern chemotherapy are worse in MSI-H patients compared to MSS tumors. However, the addition of nivolumab to chemotherapy improved the rate of pathological complete response (pCR) to 60 % in the MSI-H group.