Esophageal cancer (EC) is associated with synchronous or metachronous cancer at other primary sites. However, few studies have evaluated second malignancies after treatment. We aimed to clarify the frequencies and risk factors of second malignancies after definitive therapy for EC.
EC patients (pts) who received definitive therapy at Aichi Cancer Center Hospital between 2000 and 2010 were retrospectively analyzed. Exclusion criteria were synchronous cancer or a past cancer history. We used competing risks regression model, which defined death and the development of second malignancies as competing risk, to conduct risk analyses. Standardized incidence rate (SIR) was calculated using population-based cancer registry.
A total of 758 pts were included. Patient characteristics were as follows: male, 84%; median age, 64 (range, 32–84) years; squamous cell carcinoma, 94%; upper-third/middle-third/lower-third, 19/49/31%; clinical stage 0–I/II/III/IV, 28/24/45/3%; alcohol consumption history, 87%; smoking history, 86%. Chemotherapy, surgery, radiotherapy and endoscopic therapy were performed in 579 (76%), 374 (49%), 349 (46%), and 107 (14%) pts, respectively. With a median follow-up of 3.7 years, a total of 131 second malignancies were observed in 106 patients (14%). Cumulative incidences of second malignancies after 5 years were 7.6%. SIR of the patients was 1.83 [95% confidence interval (CI): 1.50–2.22]. Most common primary tumor sites were head and neck (20%), followed by lung (17%), stomach (16%), and colon and rectum (11%). Risk analyses revealed that age ≥ 65 [subdistribution hazard ratio (sHR): 1.51, 95% CI: 1.01–2.24, vs.
EC pts are at a high risk of second malignancies after definitive treatment. Careful follow-up is required, especially in elderly pts or pts with early-stage.
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All authors have declared no conflicts of interest.