The US Preventive Services Task Force (USPSTF) has recommended against screening for thyroid cancer in asymptomatic adults in a recent summary statement published in JAMA.
The rationale for the recommendation comes from recent incidence and mortality data. Thyroid cancer cases in the United States increased between 1975 (4.9 cases per 100,000 persons) and 2013 (15.3 cases per 100,000 persons), and the number of cases has increased by 6.7% between 1997 and 2009. However, the rate of increase has lowered to 2.1% per year between 2009 and 2013. Furthermore, the number of deaths from thyroid cancer has decreased to 0.7 deaths per 100,000 people, with a 5-year survival rate of 98.1%.
The USPSTF gave a D recommendation to screening for thyroid cancer in asymptomatic adults, noting that the negative effects of screening would most likely outweigh the benefits of a neck palpation or ultrasound screening test. The recommendation is an update from a previous C recommendation made in 1996, which indicated “insufficient evidence to recommend for or against” use of screening in this population.
Other medical societies such as the American Cancer Society, American Academy of Family Physicians, American Thyroid Association, American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinologi, as well as the Canadian Task Force on the Periodic Health Examination, have no specific recommendations for thyroid cancer screening in asymptomatic adults.
“The USPSTF found inadequate direct evidence to determine whether screening for thyroid cancer in asymptomatic persons using neck palpation or ultrasound improves health outcomes,” the USPSTF wrote in their statement. “However, the USPSTF determined that the magnitude of benefit can be bounded as no greater than small, based on the relative rarity of thyroid cancer, the apparent lack of difference in outcomes between patients who are treated vs only monitored, and the observational evidence demonstrating no change in mortality over time after introduction of a population-based screening program.”
The USPSTF noted that overdiagnosis and overtreatment are “likely consequences of screening” in asymptomatic adults, but this recommendation does not apply to adults with throat symptoms such as difficulty swallowing, hoarseness, pain, lumps, neck asymmetry, or swelling, or adults with an increased risk for thyroid cancer as a result of exposure to ionizing radiation, a diet low in iodine, or a genetic predisposition to thyroid cancer.
Furthermore, although evidence for harms resulting from screening for thyroid cancer was limited, “[c]onsiderable evidence has documented the harms of treatment with surgery and radioactive iodine therapy.”
“Although no direct studies of whether screening causes overdiagnosis exist, ecological and cross-sectional data suggest that screening for thyroid cancer leads to an increase in incidence of disease without any resulting change in mortality,” the USPSTF concluded.
Bibbins-Domingo K, Grossman DC, Curry SJ, et al. Screening for Thyroid Cancer US Preventive Services Task Force Recommendation Statement. JAMA. 2017;317(18):1882-1887. doi:10.1001/jama.2017.4011