Clinicopathological features and prognosis of patients with esophageal cancer as the second primary cancer: a large population-based analysis using the SEER program [2000–2015]

BACKGROUND: This study used the Surveillance, Epidemiology, and End Results (SEER) data to investigate clinicopathological characteristics and prognoses of patients with esophageal cancer as a second primary cancer from 2000 to 2015. METHODS: Esophageal cancer as the second primary cancer (SEPC) patient information collected from the SEER database were extracted, evaluated, and compared with only primary esophageal cancer (OPEC) patient data. Overall survival (OS) was evaluated by the Kaplan-Meier method. Univariate analysis (UVA) and multivariate analysis (MVA) by the Cox proportional hazards regression identified risk factors that predicted OS and the results were used to construct a nomogram to predict OS in SEPC patients. RESULTS: A total of 7,161 esophageal cancer patients were identified from the SEER registry, which included 813 patients (11.4%) with SEPC in the patient history. The most common cancer for the first primary cancer prior to esophageal cancer (FPC) was genital system cancer (43.5%). The median OS was 7 (95% CI: 6.69–11.31) months and was not significantly different from that of patients with OPEC. The patients with SEPC appeared with unique clinical pathological features compared with OPEC, including older age, more squamous cell carcinoma, and early stage esophageal cancer, and less lower third of esophageal cancer (P<0.001). UVA and MVA identified M stage, surgery, and chemotherapy as independent risk factors. The nomogram had a calibration index of 0.682. CONCLUSIONS: SEPC had unique clinicopathological characteristics. M stage, surgery, and chemotherapy were independently associated with OS. The nomogram accurately predicted OS.