Temporal dynamics and spatial patterns of recurrence after curative gastrectomy for gastric cancer: A multicenter hazard function analysis of 3,278 patients.

BACKGROUND: Postoperative recurrence remains the leading cause of treatment failure in gastric cancer despite curative resection. Current surveillance strategies do not adequately reflect time-varying recurrence risk. This study aimed to characterize the temporal dynamics and spatial patterns of recurrence using hazard function analysis to inform risk-adapted follow-up. METHODS: In this multicenter retrospective cohort study, 3278 patients who underwent curative gastrectomy between 2012 and 2020 at ten tertiary centers in China were included. Kernel-smoothed hazard functions were applied to estimate instantaneous recurrence risk over time. Disease-free survival (DFS) and overall survival (OS) were analyzed using Kaplan-Meier and Cox regression models. RESULTS: During a median follow-up of 61 months, 1630 patients (49.7%) developed recurrence. Overall recurrence risk peaked at 12.7 months postoperatively (hazard rate: 0.021). Stage-specific analysis showed an early and pronounced peak in stage III disease (13.9 months; hazard rate: 0.040), whereas stage II disease demonstrated a later, attenuated peak (17.0 months; hazard rate: 0.012). Peritoneal dissemination was the most aggressive pattern, peaking at 10.0 months and accounting for 29.1% of recurrences, while locoregional recurrence showed a delayed peak at 28.7 months (9.9%). Adjuvant chemotherapy status was associated with distinct recurrence hazard trajectories: patients without chemotherapy showed an earlier and higher peak at 10.3 months (hazard rate: 0.091), whereas those receiving chemotherapy showed a lower and later peak at 16.6 months (hazard rate: 0.037). Multivariable analysis identified pT4 stage, pN3 stage, lymphovascular invasion, and perineural invasion as independent risk factors, while adjuvant chemotherapy was protective. CONCLUSIONS: Gastric cancer recurrence follows stage-dependent, non-linear trajectories with distinct temporal and site-specific patterns. The high-risk window of 10-20 months postoperatively may represent a relevant period for intensified surveillance, particularly for peritoneal dissemination. These findings provide a data-informed basis for generating risk-adapted, time-sensitive follow-up hypotheses that require prospective validation.