The persistent risk of secondary malignancies in gastric neuroendocrine tumor survivors: a population-based analysis.

Gastric neuroendocrine tumors (G-NETs) are rare neoplasms with a favorable survival rate, yet they present a significant risk for second primary malignancies (SPMs). This study aims to estimate the relative risks of SPMs in G-NET survivors, exploring variations across key patient characteristics. Patients diagnosed with G-NETs were identified from the Surveillance, Epidemiology, and End Results database (2000-2021). Standardized incidence ratios (SIRs) and excess absolute risks (EARs) were calculated to assess SPM risk stratified by age at diagnosis, gender, race, latency period, marital status, and surgical intervention. Among 5072 G-NET survivors, 912 (18.0%) developed SPMs, with a median interval of 34.3 months between the diagnoses. The overall SIR for SPMs was 2.09 (95% confidence interval [CI] 1.96-2.23), corresponding to an EAR of 145.64 per 10,000 person-years. Increased risks were observed for cancers of the stomach, small intestine, thyroid, hepatobiliary system, pancreas, and esophagus. The highest risk for SPMs occurred within the first 4 years following G-NET diagnosis (SIR 2.57; 95% CI 2.11-3.1), with a gradual decline thereafter. Patients under 50 years had the highest SIRs, particularly for stomach cancer (SIR 196.28; 95% CI 160.21-238.05). Females exhibited a slightly higher SIR than males. White patients demonstrated the highest risk for stomach cancer, with an SIR of 63.88 (95% CI 57.00-71.38). G-NET survivors are at a persistently elevated risk of developing SPMs, particularly within the first 4 years of diagnosis. Age, gender, and racial factors significantly influence this risk. Personalized surveillance strategies are warranted to address these disparities and reduce SPM incidence.