Epidemiology of Patients With Thymic Carcinoma in the United States: A Systematic Literature Review

OBJECTIVES: Thymic carcinomas (TC) are rare malignancies that generally arise in the anterior mediastinum and are present at advanced stages. The current systematic literature review (SLR) aims to understand the epidemiology of thymic cancers across the United States (US).

METHODS: Electronic databases such as Embase^® and Medline^®, were searched using the combination of relevant keywords for epidemiology and thymic cancer. US-specific, English language articles with outcomes specific to epidemiology were included from the last 10 years. A standard two independent review and quality control process was followed during data collection.

RESULTS: In total five publications providing epidemiological data on thymic cancer in the US were included. As per the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database (1999-2019), thymic epithelial tumors were the most commonly reported anterior mediastinal tumors in adults aged >20 years, with an overall annual incidence of 0.48 per million inhabitants for thymic carcinomas. As per the SEER database 1973-2015, a total of 216 cases of thymic squamous cell carcinoma were identified. The prevalence was reported to be higher in males vs. females (54.6%-57.8% vs 42.2%-45.4%), while in terms of race, Whites exhibited the highest prevalence (51.8%-65.3%), followed by Asians (23.6%-23.9%). Further, among the 13,586 patients diagnosed with thymic cancer, 9041 (66.3%), 2772 (20.4%), 481 (3.5%), and 1319 (9.7%) had thymoma, thymic carcinoma, thymic neuroendocrine tumor, and other types of tumors, respectively. The standardized rate of thymic carcinoma increased from 0.03/100,000 in 2001 to 0.07/100,000 in 2015, with an AAPC of 5.3% (p <0.05).

CONCLUSIONS: The results of this study provide an inclusive overview of the epidemiology of TC. However, more studies are required which would aid in developing new prevention and treatment strategies.