Time-Varying Effects of Marital Status on Gastric Cancer: A Population-Based Study

Although prior studies have shown that marital status affects the prognosis of patients with gastric cancer, its time-varying effects are not well understood. We aimed to investigate the changes in marital status' impact over a 10-year follow-up time among patients with gastric cancer (GC) in the United States.

All patients with gastric cancer diagnosed between 2004 and 2008 in the Surveillance, Epidemiology, and End Results (SEER) database were retrieved. Married patients and unmarried patients (single, separated, divorced or widowed) with complete survival time were selected for comparisons. A total of 14,545 patients who had clinical data and follow-up information available were enrolled. We used Kaplan-Meier analyses and time-dependent flexible parametric models to estimate time-varying hazard ratios (HRs).

Unmarried GC patients had worse overall and cancer-specific survival compared with married patients (log-rank test: P < 0.001 and P < 0.001, respectively). The time-varying analysis found that unmarried patients had a significantly higher risk of overall mortality during the 10-year follow-up time, with the lowest adjusted hazard ratio (HR) at 12 months after diagnosis (HR at 12 months, 1.08; 95% CI, 1.03-1.15). For cancer-specific mortality, the time-varying adjusted HR of unmarried patients was significantly higher initially (HR at 12 months, 1.08; 95% CI, 1.02-1.14) but decreased to null after 20 months (HR at 24 months = 1.04; 95% CI = 0.99-1.11).

Unmarried patients had a higher risk of cancer-specific mortality during the 20 months after gastric cancer diagnosis, which may be an appropriate time frame for intervention.