Thyroid ultrasound imaging could be used to identify patients who have a low risk of cancer for whom biopsy could be postponed, according to a study by Rebecca Smith-Bindman, M.D., of the University of California, San Francisco, and colleagues published August 26, 2013 in JAMA Internal Medicine.

The retrospective case-control study of 8,806 patients who underwent 11,618 thyroid ultrasound imaging examinations from January 2000 through March 2005 included 105 patients diagnosed as having thyroid cancer.

Thyroid nodules were common in patients diagnosed as having cancer (96.9 percent) and patients not diagnosed as having thyroid cancer (56.4 percent). Three ultrasound nodule characteristics—microcalcifications (odds ratio [OR] 8.1), size greater than 2 cm (OR, 3.6), and an entirely solid composition (OR, 4.0)—were the only findings associated with the risk of thyroid cancer. Compared with performing biopsy for all thyroid nodules larger than 5 mm, adoption of this more stringent approach requiring two abnormal nodule characteristics to prompt biopsy would reduce unnecessary biopsies by 90 percent while maintaining a low risk of cancer, according to the study results.

"Although thyroid nodules are common, most (98.4 percent) are benign, highlighting the importance of being prudent in deciding which nodules should be sampled to reduce unnecessary biopsies."The study concludes, "Adoption of uniform standards for the interpretation of thyroid sonograms would be a first step toward standardizing the diagnosis and treatment of thyroid cancer and limiting unnecessary diagnostic testing and treatment."

The study was supported by grants from the National Cancer Institute and a SEED grant from the Department of Radiology and Biomedical Engineering, University of California, San Francisco.