USPSTF reinforces recommendation against thyroid cancer screening
The USPSTF recommends against thyroid screening in asymptomatic adults, issuing guidance on a “D” rating (recommends against screening).
“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,” wrote the USPSTF in a recommendation statement published in the Journal of the American Medical Association.
The incidence rate of thyroid cancer in the U.S. when measured in 2013 was 15.3 cases per 100,000 persons, more than a three-fold increase from the 4.9 cases per 100,000 people measured in 1975. However, most thyroid cancers have a good prognosis—the five-year survival rate is 98 percent—making it difficult for screening to prove its worth.
More detection led to more treatment, but the combination of a stagnant mortality rate and documented surgical harms led the USPSTF to reconsider their rating. To be clear, there’s very limited evidence for harms of screening itself, but surgical treatments have resulted in hypocalcemia, vocal cord paralysis, and laryngeal nerve palsy.
It’s important to note these recommendations exclude patients with pain, difficulty swallowing, or other throat symptoms, in addition to patients with a history of radiation exposure. This was a provision specifically added after physicians voiced their opposition during the public comment period opened by the USPSTF in November.
“Many respondents shared personal stories of how their clinician noticed a lump during physical examination, often prompted by symptoms such as hoarseness or throat pain, and expressed concern that the recommendation would prevent diagnosis of such cancer cases,” wrote the USPSTF. “Clinicians who interpreted the recommendation as discouraging them from performing neck examination also expressed concern. In response, the USPSTF expanded the Clinical Considerations section to clarify that this recommendation does not apply to persons who experience hoarseness, pain, difficulty swallowing, or other throat symptoms or persons who have lumps, swelling, asymmetry of the neck, or to other reasons for a neck examination.”
This guidance is an update on their previous position, issued in 1996, which couldn't recommend for or against screening due to a lack of evidence. Since then, the USPSTF commissioned a systematic evidence review, finding the "magnitude of the overall benefits of screening and treatment can be bounded as no greater than small."
The USPSTF joins several other healthcare organizations in not recommending widespread thyroid cancer screening, including the American Cancer Society, the American Academy of Family Physicians and the Canadian Task Force on Preventative Health Care.