Risk and survival of second primary malignancies following diagnosis of gastric mucosa-associated lymphoid tissue lymphomas: A population-based study.

Whether gastric mucosa-associated lymphoid tissue lymphoma (GML) is associated with a higher risk of second primary malignancy (SPM) remains controversial. This study aimed to evaluate the detailed risk of SPM and its prognosis in patients with GML based on a large population-based cohort. The Surveillance, Epidemiology, and End Results database was searched to identify patients who were diagnosed with GML during 2000-2014. The standardized incidence ratio was used to estimate the relative risk of developing SPM. Overall survival was evaluated using the Kaplan-Meier method with the log-rank test, as well as Cox regression analysis. Among 3,379 patients with GML, 416 patients (12.31%) developed SPMs. Compared to the general US population, GML patients had a significantly increased risk of developing SPM (standardized incidence ratio: 1.46, 95% CI: 1.33-1.61). The SPM sites were stomach, lung and bronchus, small intestine, thyroid, mouth, and non-Hodgkin's lymphoma. The risk of developing SPM in GML patients varied according to clinical and demographic characteristics. Patients with younger age (<50 year), chemotherapy use and radiotherapy use had the higher risk of developing SPMs. Relative to patients with only GML, GML patients who developed the SPMs had significantly poorer overall survival (P < 0.001). Among GML patients with SPMs, poor overall survival was independently associated with non-localized SPM disease, shorter latency period (<60 months), chemotherapy use and older age (≥70 year). Patients with GML had an elevated risk of developing SPM, which was associated with a poor prognosis. These findings may be useful for improving follow-up surveillance for patients with GML.