Perineural invasion and survival after radical gastrectomy for gastric cancer: A propensity score-adjusted cohort study

BACKGROUNDPerineural invasion (PNI) is associated with poor survival in gastric cancer but often cooccurs with advanced pathological features.Baseline imbalances in previous observational cohorts have left PNI's independent prognostic value uncertain. AIMTo evaluate the associations between PNI and long-term survival after radical gastrectomy using complementary propensity score methods. METHODSThis single-center retrospective cohort study included 286 patients who underwent radical gastrectomy between January 2013 and June 2016.Overall survival (OS) and recurrence-free survival (RFS) were evaluated.Multivariable regression was applied to the original cohort.Overlap weighting (OW) was the primary propensity score approach, and propensity score matching (PSM) was used as a sensitivity analysis.Propensity score adjustment was combined with multivariable Cox regression. RESULTSAmong the 286 patients, 102 (35.7%) had PNI.Lymphovascular invasion and a higher pT category were independently associated with PNI.OW reduced all modeled standardized mean differences to below 0.10.After multivariable Cox regression in the original cohort, PNI remained associated with poorer OS [hazard ratio (HR): 1.92; 95% confidence interval (CI): 1.23-3.00;P = 0.004] and RFS (HR: 1.55; 95%CI: 1.02-2.37;P = 0.042).In the OW cohort, PNI remained associated with poorer OS (HR: 1.83; 95%CI: 1.17-2.84;P = 0.008), but not RFS (HR: 1.46; 95%CI: 0.96-2.22;P = 0.078).The full PSM models were unstable and did not show statistically significant associations.4 / 31 CONCLUSION PNI was associated with poorer OS after radical gastrectomy for gastric cancer, even after adjusting for other clinical and pathological factors.