Low level of microsatellite instability correlates with short disease-free survival of gastric cancer patients undergoing neoadjuvant chemotherapy.
Jiang D., Shu C., Zhang W., Sun L., Zhang M., He Y., Owen G., Jin W., He D., Deng X., Liu X.
Limited studies have been reported about the function of low level of microsatellite instability (MSI-L) in cancer. The aim of our study is to unveil the prognostic role of MSI-L in gastric cancer (GC). One hundred nine patients with locally advanced GC (T3-4a, N+, M0) who underwent neoadjuvant chemotherapy plus gastrectomy with extended (D2) lymph node dissection were collected. Clinicopathological characteristics, tumour regression score, disease-free survival (DFS), and overall survival (OS) were analysed and correlated with the MSI status. The MSI status of 96 patients was identified (7 (7.3%) with MSI-H, 12 (12.5%) with MSI-L, and 77 (80.2%) with MSS). MSI-L was significantly correlated with perineural invasion (P = 0.009) and decreased MUC5AC expression (P = 0.042). Poor response to neoadjuvant chemotherapy in MSI-L patients (83.3% assessed as poor response) was observed (P = 0.501). Compared with patients with MSS tumours, patients with MSI-L tumours showed poor DFS (P = 0.018) with a hazard ratio (HR) of 2.839 (95% CI 1.131-7.124, P = 0.026) from multivariable cox regression analysis. However, this was not associated with OS (P = 0.063). MSI-L is an independent poor prognostic biomarker for the locally advanced gastric cancer treated with neoadjuvant chemotherapy. Further studies with larger sample sizes are needed for validation.