Frequent neck US in papillary thyroid cancer likely detects non-actionable findings.

Abstract

American Thyroid Association (ATA) low-intermediate-risk papillary thyroid cancer (PTC) patients without structural and biochemical evidence of disease on initial post-treatment evaluation have a low risk of recurrence. Studies have shown that with current ultrasound scans (US) and thyroglobulin assays, recurrences mostly occurred 2-8years after initial therapy. The ATA recommends that neck US be done 6-12months after surgery to establish patient's response to therapy, then periodically depending on risk of recurrence. The lack of clarity in recommendations on timing of follow-up US and fear of recurrence leads to frequent tests. To evaluate the utility of routine neck US in ATA low-intermediate-risk PTC patients with no structural disease on neck US and non-stimulated thyroglobulin <1.0ng/mL after initial therapy. A retrospective study of 93 patients from Singapore, Saudi Arabia and Argentina with ATA low (n=49) to intermediate (n=44) risk PTC was conducted between 1998 and 2017. The outcome was to measure the frequency of identifying structural disease recurrence and non-actionable US abnormalities. Over a median follow-up of 5years, five of the 93 patients (5.4%) developed structural neck recurrence on US at a median of 2.5years after initial treatment. Indeterminate US abnormalities were detected in 19 of the 93 patients (20.4%) leading to additional tests, which did not detect significant disease. In ATA low-intermediate-risk PTC with no suspicious findings on neck US and a non-stimulated thyroglobulin of <1.0ng/mL after initial therapy, frequent US is more likely to identify non-actionable abnormalities than clinically significant disease.