Study Suggests Increase in Thyroid Cancer among Veterans Linked to Increases in Diagnostic Testing
BACKGROUND:
From 1975 to 2009, the incidence of thyroid cancer in the United States nearly tripled. While some studies suggest that these trends represent an actual increase in the number of cases, several population-based studies suggest that the increase in thyroid cancer incidence is related to increases in screening, more sensitive diagnostic methods, and an increase in thyroid tumors found incidentally on non-thyroid imaging studies. Investigators in this national cross-sectional study used VA data to examine the number of Veterans who were diagnosed with thyroid cancer in the VA healthcare system between 2000 and 2012, as well as the utilization of thyroid ultrasound (US) and fine needle aspiration (FNA). Investigators then determined annual percent changes in incidence, use of thyroid US and FNA.
FINDINGS:
- Between 2000 and 2012, the incidence of thyroid cancer among Veterans within the VA healthcare system nearly doubled – from 10.3/100,000 persons to 21.5/100,000. Of the nearly 11 million Veterans who received healthcare during the study period, 8,870 were diagnosed with thyroid cancer.
- The number of Veterans who underwent a thyroid US increased from 4,493 in 2000 to 21,450 in 2012, and the number of Veterans who underwent a thyroid FNA increased from 275 in 2000 to 2,234 in 2012. Thus, the rates of US increased nearly fivefold (125.6/100,000 to 572.1/100,000), while the rates of FNA increased nearly sevenfold (7.0/100,000 to 46.2/100,000).
- Among Veterans receiving a thyroid cancer diagnosis, 69% underwent a thyroid US, 32% underwent a thyroid FNA, and 30% did not have either test in the VA healthcare system.
LIMITATIONS:
- Investigators relied onICD-9 and CPT codes in VA data, which are subject to bias and coding errors.
- ICD-9 codes do not provide specific information about tumors, treatment, and outcomes. Thus, it is not possible to determine whether the increase in incidence occurred primarily in one type of thyroid cancer or another – or in smaller or larger tumors.
IMPLICATIONS:
- Findings suggest the increase in thyroid cancer incidence may reflect over-diagnosis of subclinical disease due to increased thyroid US and FNA utilization, although these findings do not rule out a true increase in thyroid cancer incidence.
AUTHOR/FUNDING INFORMATION:
This study was partly funded by HSR&D. Drs. Hartman, Kramer, and Chiao are part of HSR&D's Center for Innovations in Quality, Effectiveness and Safety, Houston, TX.
Zevallos J, Hartman C, Kramer J, Sturgis E, and Chiao E. Increased Thyroid Cancer Incidence Corresponds to Increased Utilization of Thyroid Ultrasound and Fine Needle Aspiration: A Population-Based Study in the Veterans Affairs Healthcare System. Cancer. November 6, 2014;e-pub ahead of print.
