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.