Background: Thyroid cancer incidence has significantly increased in the United States over the past few decades. Recent studies have suggested a change in thyroid cancer incidence trends following 2013. The main objective of this study was to update the data on thyroid cancer incidence and mortality trends in the United States. Methods: Thyroid cancer incidence and incidence-based mortality trends were evaluated using the Surveillance, Epidemiology, and End Results-18 cancer registry. Cases of thyroid cancer diagnosed in 2000–2018 and thyroid cancer deaths during 2000–2018 were included. Annual percent change (APC) was calculated using joinpoint regression analysis. Results: Among 197,070 patients, female (75.6%) and white (81.0%) patients comprised the majority of cases. Papillary thyroid carcinoma (PTC) was the most common histology (89.1%). Incidence rates increased during 2000–2009 (APC 6.80, 95% confidence interval [CI 6.46 to 7.13]) and 2009–2014 (APC 2.58 [CI 1.71 to 3.47]) and then decreased during 2014–2018 (APC −2.33 [CI −3.15 to −1.51]). The incidence trends for PTC overall, localized disease, and tumors ≤1.0 cm mirrored the overall thyroid cancer trends, while incidence rates for regional disease stabilized during 2015–2018 (APC −1.65 [CI −4.09 to 0.84]). The incidence of distant disease decreased during 2015–2018 (APC −17.86 [CI −26.47 to −8.25]). The incidence of tumors ≤1.0 cm decreased (APC −5.83 [CI −7.24 to −4.40]), while the incidence of tumors 1.1–2.0 cm (APC −0.10 [CI −1.16 to 0.96]), 2.1–4.0 cm (APC 1.12 [CI −0.17 to 2.43]), and >4.0 cm (APC −1.13 [CI −4.58 to 2.45]) stabilized during the most recent 4–6 years. Incidence-based mortality increased throughout 2000–2018 (average APC 1.35 [CI 0.88 to 1.82]). Conclusions: Thyroid cancer incidence rates have declined since 2014. Similar declines are noted for PTC, localized disease, and tumors ≤1.0 cm, but not for tumors >2.0 cm. Incidence-based mortality rates continue to increase. These findings suggest that changing patterns in the management of thyroid nodules may have led to a decrease in diagnosis of small indolent tumors, but not more advanced tumors.

Thyroid cancer is the most rapidly increasing cancer in the United States.¹ The incidence rates increased by 3% annually from 1974 to 2013, from 4.6 per 100 000 person-years from 1974 to 1977 to 14.4 per 100 000 person-years from 2010 to 2013.² In adults, it has been hypothesized that overdiagnosis, attributable to the increased ability to detect and diagnose small, indolent tumors that would remain asymptomatic and otherwise not require treatment, is responsible for this phenomenon.^3-7 However, others hypothesize that increased thyroid cancer incidence-based mortality rates since the late 1980s and increased incidence rates of large tumors and advanced-stage disease demonstrate a true increase in occurrence of thyroid cancer.^2,8,9

We performed a population-based historical cohort study using the Surveillance, Epidemiology, and End Results (SEER) database to determine trends in the incidence of major salivary gland cancer and to evaluate the effect of sex, tumor size, histology, primary site, and extent of disease. Participants were men and women with major salivary gland cancer, diagnosed 1973–2009. The incidence of major salivary gland cancer increased from 10.4 per 1,000,000 in 1973 to 16 per 1,000,000 in 2009 (annual percent change [APC] 0.99; 95% confidence interval [CI] 0.78 to 1.20; p < 0.05). The incidence of parotid cancers increased (APC 1.13; 95% CI 0.88 to 1.39; p < 0.05) and paralleled the increase in major salivary gland cancer overall. There was an increase in the incidence of tumors measuring 0 to 2.0 cm (APC 1.99; 95% CI 0.61 to 3.38; p < 0.05), but no change in tumors measuring 2.1 to 4.0 cm (APC 1.02; 95% CI -0.46 to 2.52; p > 0.05) and tumors measuring >4 cm (APC -0.52; 95% CI -1.72 to 0.69; p > 0.05). There was an increase in the incidence of regional (APC 0.77; 95% CI 0.32 to 1.23; p < 0.05) and distant (APC 2.43; 95% CI 1.43 to 3.45; p < 0.05) disease, but not localized disease (APC 0.35; 95% CI 0 to 0.71; p > 0.05). We conclude that the incidence of major salivary gland cancer is increasing, especially small parotid tumors. The incidence of tumors with regional and distant metastasis is also increasing. These findings highlight the need for further research on the etiology of salivary gland cancer, which may reveal opportunities for further public health efforts aimed at prevention.

Objective: To evaluate the impact of county‐level socioeconomic status on survival in patients with oropharyngeal cancer in the United States.Study Design: Retrospective cohort study via a large population‐based cancer database.Methods: Data were extracted from the SEER 18 database (Surveillance, Epidemiology, and End Results) of the National Cancer Institute. The study cohort included 18,791 patients diagnosed with oropharyngeal squamous cell carcinoma between 2004 and 2012.Results: Patients residing in counties with a low socioeconomic status index had worse overall survival (56.5% vs 63.0%, P <. 001) and disease‐specific survival (62.7% vs 70.3%, P <. 001) than patients residing in counties with a high socioeconomic status index. On multivariable analysis, residing in a county with a low socioeconomic status index was associated with worse overall survival (hazard ratio, 1.21; 95% CI, 1.14‐1.29; P <. 001) and disease‐specific survival (hazard ratio, 1.21; 95% CI, 1.12‐1.30; P <. 001), after adjusting for race, age, sex, marital status, year of diagnosis, site, American Joint Committee on Cancer stage group, presence of distant metastasis, presence of unresectable tumor, histologic grade, surgical resection of primary site, treatment with neck dissection, and radiation therapy.Conclusion: Residing in a county with a low socioeconomic status index is associated with worse survival. Further research is needed to elucidate the mechanism by which socioeconomic status affects survival in oropharyngeal cancer.