Evaluation of the prevalence of metachronous second primary malignancies in hypopharyngeal carcinoma and their effect on outcomes

BACKGROUND: To investigate the clinical characteristics of metachronous second primary malignancies (Met‐SPMs) and its impact on prognosis in hypopharyngeal carcinoma (HPC). METHODS: We reviewed 593 newly diagnosed HPC patients without invasive synchronous SPMs (Syn‐SPMs) who were treated in our cancer center between 2009 and 2019. According to the status during follow‐up, patients were classified into three groups: (a) without SPMs (No‐SPMs, n = 440), (b) with tumors in situ in the esophagus or stomach (Tis, n = 80), or (c) with Met‐SPMs (n = 73). RESULTS: The median follow‐up time for entire cohort (n = 593) was 66.7 months. Met‐SPMs were present in 12.3% of the cohort (73/593). The predominant site of SPMs was esophagus, followed by lung, oral cavity, thyroid, stomach, and oropharynx. In Met‐SPMs group, both index tumor and SPMs were the main causes of death. Tis group exhibited comparable 5‐year overall survival (OS) and disease‐specific survival (DSS) with that of No‐SPMs group. The Met‐SPMs group had similar 5‐year OS rate and better 5‐year DSS rate of 47.3% versus 43.6% (odds ratio [OR], 0.931; 95% confidence interval [CI], 0.681–1.274, p = 0.657) and 66.3% vs. 46.2% (OR, 0.600; 95% CI, 0.402–0.896, p = 0.012), respectively, compared with the No‐SPMs group. CONCLUSION: The overall incidence of Met‐SPMs in HPC was 12.3%. The occurrence of Met‐SPMs does not jeopardize the survival outcome of HPC. Routine surveillance of Met‐SPMs was requisite for patients with HPC.