Association between Metabolic Syndrome and Risk of Hypopharyngeal Cancer: A Nationwide Cohort Study from Korea

SIMPLE SUMMARY: The incidence of hypopharyngeal cancer has been rapidly increasing, but hypopharyngeal cancer has a poorer prognosis compared to other head and neck cancers. This is because the diagnosis of hypopharyngeal cancer is late due to few symptoms in the early stages. Thus, early diagnosis and prevention are very important in the management of hypopharyngeal cancer. Metabolic syndrome, including a combination of obesity, impaired lipid and glucose metabolism, and hypertension, has recently attracted attention as a risk factor for various cancers. In this study, we investigated the association between metabolic syndrome and hypopharyngeal cancer. We confirmed that metabolic syndrome lowered the risk of hypopharyngeal cancer regardless of age, sex, smoking, and alcohol consumption. This inverse association was more prominent in women than in men. ABSTRACT: This study evaluated the relationship between metabolic syndrome (MS) and the risk of hypopharyngeal cancer. This retrospective cohort study used data from the Korean National Health Insurance Research Database. A total of 4,567,890 participants who underwent a health checkup in 2008 were enrolled. The participants were followed until 2019, and the incidence of hypopharyngeal cancer was analyzed. We evaluated the risk of hypopharyngeal cancer according to the presence of MS, including obesity, dyslipidemia, hypertension, and diabetes, using a multivariate Cox proportional hazards model adjusted for age, sex, alcohol consumption, and smoking. During the follow-up period, 821 were newly diagnosed with hypopharyngeal cancer. MS was inversely associated with the risk of hypopharyngeal cancer (hazard ratio (HR), 0.83 [95% confidence interval (CI), 0.708–0.971]). Large waist circumference and high triglyceride levels among MS elements were both inversely related to the risk of hypopharyngeal cancer (HR: 0.82 [95% CI, 0.711–0.945] and 0.83 [95% CI, 0.703–0.978], respectively). The risk of hypopharyngeal cancer decreased with increasing comorbidity of MS in women (N = 0 vs. N = 1–2 vs. N ≥ 3; HR = 1 vs. HR = 0.511 [95% CI, 0.274–0.952] vs. HR = 0.295 [95% CI, 0.132–0.66]), but not in men. This study may improve our etiological understanding of hypopharyngeal cancer.