In the Journals

PET imaging used in about 20% of differentiated thyroid cancers

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October 2, 2015

About one-fifth of patients with differentiated thyroid cancer underwent PET imaging, and results of PET scans changed management of differentiated thyroid cancer in about 30% of those patients, according to recent study findings published in Thyroid.

“The rising incidence of low-risk thyroid cancer is changing treatment paradigms,” the researchers wrote. “Interestingly, management is being driven by risk assessment, and a ‘one size fits all’ approach to thyroid cancer treatment is no longer recommended. The same should be true for posttreatment surveillance. The choice of imaging modality should be tailored toward the patient’s risk, the clinical suspicion for recurrent or persistent disease, and the serum thyroglobulin.”

Jaime L. Wiebel, MD, of the University of Michigan, and colleagues evaluated 585 patients with differentiated thyroid cancer who underwent surgery from 2006 to 2011 to determine the rate of utilization of and the indications for PET scans and changes in management based on results. Median follow-up was 5 years.

Jaime Wiebel

Jaime L. Wiebel

At least one PET scan was performed on 19% of patients for a total of 200 PET scans. One PET scan was performed on 54.1% of patients, 25.2% had two, 10.8% had three, 6.3% had four, 2.7% had five and 0.9% had more than five scans.

Follow-up of a previous scan was the most common indication for PET scan (28.4%), followed by elevated thyroglobulin and negative radioactive iodine (26%), evaluation of extent of disease (16.5%), evaluation of an abnormality on another imaging test (11%), rising thyroglobulin (9%), positive thyroglobulin antibodies (6.5%), unknown indications (1.5%) and other indications (1%).

Sixty-two percent of PET scans were positive.

Observation was the most common management strategy based on a PET scan (55%), followed by surgery (33%), chemotherapy or radiation (11.5%) and palliative care (0.5%). Management was changed in 29.5% of cases after the scan.

“The present study suggests that the PET scan is most helpful in patients with higher thyroglobulin levels in the setting of a negative radioiodine scan or when evaluating a rising thyroglobulin and that routine follow-up of a previous scan is least likely to change management,” the researchers wrote. “In addition, attention should be paid to cost-effectiveness and radiation exposure. Future research needs to investigate whether use of an imaging modality can affect patient morbidity and mortality, rather than simply identifying recurrent or persistent thyroid cancer.” – by Amber Cox

Disclosure: The researchers report no relevant financial disclosures.

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