Susan S. Devesa

Importance: Thyroid cancer incidence has increased substantially in the United States over the last 4 decades, driven largely by increases in papillary thyroid cancer. It is unclear whether the increasing incidence of papillary thyroid cancer has been related to thyroid cancer mortality trends. Objective: To compare trends in thyroid cancer incidence and mortality by tumor characteristics at diagnosis. Design, Setting, and Participants: Trends in thyroid cancer incidence and incidence-based mortality rates were evaluated using data from the Surveillance, Epidemiology, and End Results-9 (SEER-9) cancer registry program, and annual percent change in rates was calculated using log-linear regression. Exposure: Tumor characteristics. Main Outcomes and Measures: Annual percent changes in age-adjusted thyroid cancer incidence and incidence-based mortality rates by histologic type and SEER stage for cases diagnosed during 1974-2013. Results: Among 77 276 patients (mean [SD] age at diagnosis, 48 [16] years; 58 213 [75%] women) diagnosed with thyroid cancer from 1974-2013, papillary thyroid cancer was the most common histologic type (64 625 cases), and 2371 deaths from thyroid cancer occurred during 1994-2013. Thyroid cancer incidence increased, on average, 3.6% per year (95% CI, 3.2%-3.9%) during 1974-2013 (from 4.56 per 100 000 person-years in 1974-1977 to 14.42 per 100 000 person-years in 2010-2013), primarily related to increases in papillary thyroid cancer (annual percent change, 4.4% [95% CI, 4.0%-4.7%]). Papillary thyroid cancer incidence increased for all SEER stages at diagnosis (4.6% per year for localized, 4.3% per year for regional, 2.4% per year for distant, 1.8% per year for unknown). During 1994-2013, incidence-based mortality increased 1.1% per year (95% CI, 0.6%-1.6%) (from 0.40 per 100 000 person-years in 1994-1997 to 0.46 per 100 000 person-years in 2010-2013) overall and 2.9% per year (95% CI, 1.1%-4.7%) for SEER distant stage papillary thyroid cancer. Conclusions and Relevance: Among patients in the United States diagnosed with thyroid cancer from 1974-2013, the overall incidence of thyroid cancer increased 3% annually, with increases in the incidence rate and thyroid cancer mortality rate for advanced-stage papillary thyroid cancer. These findings are consistent with a true increase in the occurrence of thyroid cancer in the United States.

BACKGROUND: Incidence rates for esophageal adenocarcinoma previously were reported to be increasing rapidly, especially among white males. Rates for gastric cardia adenocarcinoma also were observed to be rising, although less rapidly. In this article, the authors update the incidence trends through 1994 and further consider the trends by age group. METHODS: Surveillance, Epidemiology, and End Results (SEER) program data were used to calculate age-adjusted incidence rates for esophageal carcinoma by histologic type and gastric adenocarcinoma by anatomic subsite. RESULTS: Among white males, the incidence of adenocarcinoma of the esophagus rose > 350% since the mid-1970s, surpassing squamous cell carcinoma around 1990. Rates also rose among black males, but remained at much lower levels. To a lesser extent, there were continuing increases in gastric cardia adenocarcinoma among white and black males, which nearly equaled the rates for noncardia tumors of the stomach in white men. The upward trend for both tumors was much greater among older than younger men. Although the incidence also rose among females, rates remained much lower than among males. CONCLUSIONS: Previously reported increases of esophageal adenocarcinoma are continuing, most notably among white males. Cigarette smoking may contribute to the trend through an early stage carcinogenic effect, along with obesity, which may increase intraabdominal pressure and predispose to gastroesophageal reflux disease. Further research into esophageal and gastric cardia adenocarcinoma is needed to clarify the risk factors and mechanisms responsible for the upward trends as well as the racial and gender disparities in incidence.

Because the causes of most lymphoid neoplasms remain unknown, comparison of incidence patterns by disease subtype may provide critical clues for future etiologic investigations. We therefore conducted a comprehensive assessment of 114,548 lymphoid neoplasms diagnosed during 1992-2001 in 12 Surveillance, Epidemiology, and End Results (SEER) registries according to the internationally recognized World Health Organization (WHO) lymphoma classification introduced in 2001. Cases coded in International Classification of Diseases for Oncology, Second Edition (ICD-O-2), were converted to ICD-O-3 for WHO subtype assignment. Age-specific and age-adjusted rates were compared by sex and race (white, black, Asian). Age-adjusted trends in incidence were estimated by sex and race using weighted least squares log-linear regression. Diverse incidence patterns and trends were observed by lymphoid neoplasm subtype and population. In the elderly (75 years or older), rates of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma increased 1.4% and 1.8% per year, respectively, whereas rates of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) declined 2.1% per year. Although whites bear the highest incidence burden for most lymphoid neoplasm subtypes, most notably for hairy cell leukemia and follicular lymphoma, black predominance was observed for plasma cell and T-cell neoplasms. Asians have considerably lower rates than whites and blacks for CLL/SLL and Hodgkin lymphoma. We conclude that the striking differences in incidence patterns by histologic subtype strongly suggest that there is etiologic heterogeneity among lymphoid neoplasms and support the pursuit of epidemiologic analysis by subtype.