Analyzing Risk Factors for Second Malignancies in Early Gastric Carcinoma from the SEER Database

A retrospective study was conducted based on a large population analyzing GC patients treated between 2010 and 2015 to elucidate the clinical features and predictive risk factors for developing secondary primary malignancies (SPMs). The cumulative incidence of SPM in patients was determined using Kaplan‒Meier analysis. Competing risk analyses adjusted for mortality were used after stratified Cox proportional hazard regression models and multivariate analyses to identify independent SPM predictors. A total of 3,289 of 167,747 GC sufferers were included in our analytic cohort. Of these, 155 patients were diagnosed with SPM. Histologic types other than adenocarcinoma (AC) and signet ring cell carcinoma (SRCC) were independent risk factors for developing SPM (hazard ratio [HR] of 2.262, 95% confidence interval [CI] of 1.146–4.465, P  = 0.019) in multivariate Cox regression analysis. The surgical method, including both biopsy/local excision (HR of 2.3, CI of 1.291–4.095, P  = 0.005) and subtotal/total resection (HR of 1.947, CI of 1.028–3.687, P  = 0.041), chemotherapy (HR of 1.527, CI of 1.006–2.316, P  = 0.047 and histologic type (HR of 2.318, CI of 1.193–4.504, P  = 0.013)), were independent risk factors in the competitive risk model. Meanwhile, in subgroup analyses stratified by chemotherapy, an increased risk of developing SPM was associated with older age. Furthermore, we developed and internally validated a nomogram for predicting the cumulative incidence of SPM in GC patients (C-index = 0.73 for 72 months). These findings suggested that in specific histologic types of GC, the lymph node infiltration region missed after local surgical resection and concomitant chemotherapy would have an increased risk of SPM.