Risk factors for second primary cancers in patients with curatively resected gastric cancer.

Purpose: Despite improving long-term outcomes after gastrectomy for gastric cancer (GC), screening methods for second primary cancer (SPC) following resection remain challenging. This study aimed to investigate the cumulative incidence and risk factors for SPC in patients with curative resection for GC.

Methods: We included 1128 patients who underwent R0 resection for Stage I/II/III GC. Incidence of duplicate cancers before and after gastrectomy was investigated. The cumulative incidence of SPC following gastrectomy was calculated, and the relationship between SPC occurrence and clinicopathological factors was analyzed.

Results: During a median postoperative follow-up of 64 months, the most common SPCs were lung, prostate, and colorectal cancers. Additionally, lung and pancreatic cancers occurred significantly more frequently after gastrectomy than before. The cumulative incidence of SPCs was 7% at 5 years,  18% at 10 years, and 29% at 15 years. Multivariate analysis identified male sex, postoperative carcinoembryonic antigen (CEA) levels ≥ 5.0 ng/mL, and albumin levels ≤ 3.8 g/dL at one month after gastrectomy as significant factors associated with SPC development.

Conclusion: After gastrectomy for gastric cancer (GC), enhanced surveillance for SPCs can be tailored based on three factors: male sex, postoperative CEA levels ≥ 5.0 ng/mL, and albumin levels ≤ 3.8 g/dL.