Clinical characteristics and prognostic nomogram analysis of patients with dual primary cancers with first gastric cancer: a retrospective study in China

BACKGROUND: With the improvement in diagnosis and treatment of gastric cancer (GC), the survival time of patients has been gradually prolonged. However, these survivors are at increased risk for other diseases, including second primary cancers (SPCs). Currently, there remain few central studies concerning double primary cancers with first gastric cancer (DPCFGC). Thus, this study aimed to investigate these patients’ clinical characteristics and perform prognostic nomogram analysis. METHODS: The clinical data of 78 DPCFGC patients were retrospectively collected and analyzed through the hospital electronic medical record system. Univariate and multivariate Cox regression analyses were performed to screen independent risk factors, based on which the prognostic nomogram was further constructed and validated using the R software package. Finally, Kaplan–Meier curves were plotted to explore the association of overall survival (OS) with prognostic factors and the model. RESULTS: The prevalence of DPCFGC was 0.86%, of which the proportions of synchronous and metachronous patients were 47.44% and 52.56% , respectively; 65.38% (51/78) and 34.62% (27/78) of patients were male and female, respectively. The median age at GC and SPC diagnosis was 63 and 65 years, respectively, and 52.57% of GC patients developed SPCs within 1 year. The top three SPCs were in the esophagus (19.24%), colon (16.67%), and rectum (15.39%). The most common features of GC and SPCs were adenocarcinoma, poorly and moderately differentiated histology, and pathological stages I and II. The radical resection rate of GC was significantly lower in synchronous patients than in metachronous patients (45.94% vs. 100.00%, P < 0.001), but no significant difference was noted in the radical resection rate of SPCs (35.13% vs. 46.34%, P = 0.315). The OS of DPCFGC patients was 31.03 ± 4.14 months. The pathological stage of GC and SPCs, whether to operate for GC, and diagnostic interval were independent risk factors. The predictive efficacy of the prognostic nomogram for 1-, 2- and 3-year OS in DPCFGC patients was 0.922, 0.935 and 0.796 , respectively, with good consistency and clinical applicability. The OS was significantly lower in the high-risk group than in the low-risk group. CONCLUSIONS: During follow-up, clinicians should attach great importance to the screening of GC survivors, especially at early stage in older men within 1 year after diagnosis, and be alert to the possibility of occurrent digestive system malignancies. The nomogram constructed in this study can provide a theoretical basis for the early clinical development of individualized treatment plans.