Second Cancer Incidence, Risk Factor, and Specific Mortality in Head and Neck Squamous Cell Carcinoma

Objective Second primary malignancies (SPMs) are common in patients with head and neck squamous cell carcinoma (HNSCC) and have a negative impact on their survival. This study aimed to evaluate risk factors for SPM occurrence and cause-specific mortality in Asian HNSCC patients. Study Design A retrospective cohort study. Setting University teaching hospital. Subjects Nine hundred and thirty-seven patients without previous cancer history who were treated between 2000 and 2009 and followed for at least 2 years. Methods Confirmation of SPMs was performed by histopathology. The cumulative probability of a SPM among survivors of index HNSCC was calculated using a competing risk model. Univariate and multivariate analyses were utilized to determine factors predictive of SPM occurrence and cause-specific mortality. Results Of 937 patients, cumulative incidence of SPMs was 7.2% at 0 to 6 months (synchronous), 17.9% at 5 years, and 23.1% at 10 years after index tumor diagnosis. In multivariate analyses, old age (> 60 years) (P = .002), hypopharyngeal index tumor site (P = .001), and heavy drinker (P = .001) were independently associated with the development of SPMs, and hypopharyngeal index tumor site were independent variables for SPM-specific survival (P < .001). Cumulative incidence function of SPM-specific mortality according to index tumor sites was significantly higher in the hypopharynx than other sites (P = .011). Conclusion Elderly patients, hypopharyngeal index cancer patients, or heavy drinkers may require careful surveillance for the development of SPMs. Our results may help identify and properly manage Asian patients at high risk of SPMs.