The emergence of the human papillomavirus (HPV) as the primary etiology of oropharyngeal cancer has changed head and neck cancer (HNC) epidemiology. This study described change in the age at diagnosis of oropharyngeal and non-oropharyngeal HNC in the United States in the last four decades. Using a retrospective cohort analysis, the Surveillance, Epidemiology, and End Results dataset from 1975 to 2016 was queried for eligible adult cases of HNC, grouped as oropharyngeal (n = 31,702) versus non-oropharyngeal (n = 87,108). Age at diagnosis was compared by gender (female, male) using independent t-test, and by race/ethnicity (Hispanic, non-Hispanic black, non-Hispanic white, non-Hispanic other) using analysis of variance. Joinpoint regression estimated yearly increases/decreases in age of diagnosis by sex and race/ethnicity through annual percent changes (APC), which were summarized with average annual percent changes (AAPC). Mean age at diagnosis for oropharyngeal cancer was 60.3 years. While there was initially a decrease in age at diagnosis, a 0.37% annual increase occurred from 2002 to 2016 (APC = 0.37, 95% confidence interval (CI) 0.28, 0.45). For non-oropharyngeal cancer, mean age at diagnosis was 63.2 years, with a continuous increase in age at diagnosis throughout the study period (1975–2016 AAPC = 0.08, 95% CI 0.04, 0.12). Females had higher average age at diagnosis than males for both sites, while blacks (57.4 years for oropharyngeal cancer; 59.0 years for non-oropharyngeal) had the lowest age at diagnosis of all races/ethnicity. Age at diagnosis of oropharyngeal cancer has increased significantly since 2002, while non-oropharyngeal HNC has increased significantly in the last four decades.

Background/Objectives: Thyroid cancer incidence has risen in both the United States and Canada, despite differing healthcare systems. While overdiagnosis likely partly explains this trend in adults, its impact on younger populations is unclear. We used the North American Association of Central Cancer Registries, which included 133,808 thyroid cancer cases from the United States and Canada, to assess incidence trends among pediatric, adolescent, and young adult (PAYA) populations. Methods: Age-adjusted incidence rates (AAIR) per 100,000 person-years (PY) were compared using rate ratios (RR), stratified by sex, age, race/ethnicity (United States only), and histology. Joinpoint regression estimated annual percentage changes (APC) and average APCs (AAPC) in AAIRs. From 1995 to 2014, thyroid cancer incidence increased by 137%. Significant increases occurred across all age groups (0–14, 15–24, 25–34, 35–39 years). The rate increase was highest for papillary thyroid cancer (AAPC = 5.50, 95% CI 5.06, 5.94), and among individuals aged 35–39 years (AAPC = 5.99, 95% CI 4.84, 7.15). Of racial/ethnic groups in the United States, non-Hispanic White individuals had the highest AAIR (6.22 per 100,000 PY). Mortality has changed minimally. Conclusions: Over the past two decades, thyroid cancer incidence has increased in individuals under 40. While evidence suggests that overdiagnosis primarily accounts for this trend, other contributing factors cannot be ruled out. Further research and surveillance of the drivers of increased incidence are critical.