USPSTF: Do Not Screen for Thyroid Cancer in Asymptomatic Individuals

The US Preventive Services Task Force (USPSTF) has provided a D recommendation (discourages the use of service) for thyroid cancer screening in asymptomatic individuals.

Thyroid cancer incidence has increased nearly 3 times over a 40-year period—15.3 cases per 100,000 in 2013 compared with 4.9 cases per 100,000 in 1975. However, mortality rates have not seen much of a spike: they have increased by 0.7 deaths per 100,000 persons each year. It’s also important to note that the 5-year survival for the disease ranges from 99.9% for localized disease to 55.3% for individuals who have metastases.

The USPSTF revisited neck palpation or ultrasound as a screening technique used in asymptomatic individuals to evaluate its impact on health outcomes. The recommendations, however, do not apply to individuals with hoarseness, pain, difficulty swallowing, or other throat symptoms or persons who have lumps, swelling, asymmetry of the neck, or other reasons for a neck examination. It also does not apply to persons at increased risk of thyroid cancer because of a history of exposure to ionizing radiation, particularly persons with a diet low in iodine, an inherited genetic syndrome associated with thyroid cancer, or a first-degree relative with a history of thyroid cancer.

The USPSTF committee found no direct evidence that compared screened versus unscreened populations or immediate surgery versus surveillance or observation that showed an impact on health outcomes such as mortality, quality of life, or harms.

“The USPSTF found inadequate direct evidence on the harms of screening but determined that the magnitude of the overall harms of screening and treatment can be bounded as at least moderate, given adequate evidence of harms of treatment and indirect evidence that overdiagnosis and overtreatment are likely to be substantial with population-based screening,” the authors noted.

The research need, according to the report, published in JAMA, point to the need for observational studies of early treatment versus surveillance or observation of patients with small, well-differentiated thyroid cancer to identify patients at the highest risk for clinical deterioration. The experts also noted the absence of risk prediction tools or biomarkers to understand the prognosis of differentiated thyroid cancer.

While there is no direct evidence that ascertains that screening for thyroid cancer can result in overdiagnosis, the fact that increased incidence has not resulted in increased mortality is telling, according to the report.

“Overdiagnosis occurs because screening for thyroid cancer often identifies small or slow growing tumors that might never affect a person during their lifetime,” Task Force member Seth Landefeld, MD, said in a statement for USPSTF. “People who are treated for these small tumors are exposed to serious risks from surgery or radiation, but do not receive any real benefit.”

Reference

US Preventive Services Task Force. Screening for thyroid cancer: US Preventive Services Task Force recommendation statement. JAMA. 2017;317(18):1882-1887. doi: 10.1001/jama.2017.4011.