Microsatellite instability-high gastric cancer patients may benefit from adjuvant radiotherapy

Gastric cancer remains one of the deadliest types of cancer despite the improvements in therapy regimens. The knowledge about specific molecular and histopathologic features of gastric tumors leads toward targeted therapy protocols. Patients with microsatellite instability-high cancer exhibit special characteristics regarding the response to therapy. These patients benefit from specific immunotherapy regimens and respond poorly to conventional therapy. Our study aimed to evaluate the effect of chemotherapy and chemoradiotherapy on the survival of patients with microsatellite instability gastric cancer in our institution. The results of our study show an increase in survival in the microsatellite instability-high group of patients who received radiotherapy (p=0.04). Since all the recent studies recommend radiotherapy only in patients with incompletely resected disease or those with less than D2 lymphadenectomy, our study offers a novelty suggestion in consideration of therapeutic options. If the benefit of radiotherapy can be confirmed in a larger sample of patients, radiotherapy could be a part of tailored therapy for microsatellite instability-high (MSI-H) gastric cancer.