Megan Haymart, MD, and colleagues at the University of Michigan have discovered that while widespread use of ultrasound increased the diagnosis of low-risk thyroid cancers, it may lead to harm following thyroid surgery. Click through the slides below for details on their study and take home points for clinical practice.
Thyroid Cancer and Ultrasound. Thyroid cancer incidence has increased in the US with the greatest change in adults aged ≥65 years and the cause for the increase is controversial. Authors of the study sought to evaluate the relationship between area-level use of imaging and thyroid cancer incidence.
The Study. Authors conducted a longitudinal study looking at imaging patterns in Medicare patients aged ≥65 years and assessed SEER-Medicare regions in relation to differentiated thyroid cancer diagnosis. A time-trend analysis of use of thyroid ultrasound was performed from 2002-2013 with the main outcome measure being incidence of differentiated thyroid cancer.
The Results. Thyroid ultrasound as initial imaging per 100 000 people enrolled in Medicare increased over time at a rate of 20.9% per year from 2001-2013 (p<.001). Majority of patients that met outcome measure had papillary thyroid cancer (85.7%) and localized disease (69.9%) with over 35.6% having tumors ≤1 cm. Use of thyroid ultrasound was significantly associated with thyroid cancer incidence (p<.001) and 1833 fewer thyroid cancers would have been diagnosed between 2003-2013 if ultrasound use had remained constant at 2002 levels.
Take Home Points:
- Thyroid ultrasound use has increased dramatically over last 2 decades
- Women and patients with comorbidities are particularly vulnerable to widespread thyroid ultrasound testing
- The more often an ultrasound is used as first imaging modality, the more diagnoses of thyroid cancer are made
- Data supports the notion that overdiagnosis is responsible for increased incidence of thyroid cancers in the US
- Prior investigation has suggested that near zero mortality rate for low-risk thyroid cancer, especially if localized and ≤1 cm
Perspective. “The common misconception that the goal of medicine is to detect/diagnose disease is addressed in this work and should be considered the primary finding of this study. Finding cancer is a sensitive subject for both clinicians and patients and conventional wisdom endorses early diagnosis and early treatment. As diagnoses increase, however, we also see a rise in a negative impact of treatment in the forms of surgical, medical, and psychological morbidity."
Reference: Haymart MR, Banerjee M, Reyes-Gastelum D, Caoili E, Norton EC. Thyroid ultrasound and the increase in diagnosis of low-risk thyroid cancer. J Clin Endocrinol Metab. 2018.
