Long-term ultrasound follow-up unnecessary after low-risk papillary thyroid cancer
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Follow-up ultrasound scans conducted in adults treated for low- to intermediate-risk papillary thyroid cancer are more likely to detect nonactionable findings than clinically significant disease, according to study data.
“The overall structural recurrence rate observed in our study of American Thyroid Association low- to intermediate-risk patients was 5.4% over a median follow-up period of 2.5 years after surgery,” Samantha Peiling Yang, MBBS, MRCP, senior consultant in the department of endocrinology at the National University Hospital in Singapore, and colleagues wrote in a study published in Clinical Endocrinology. “Importantly, the recurrent disease was identified as small-volume metastatic cervical lymph nodes that were often nonactionable.”
Researchers retrospectively analyzed medical records from adults with low- or intermediate-risk papillary thyroid cancer treated at the National University Hospital in Singapore. All participants underwent total thyroidectomy and had serial neck ultrasound scans during follow-up between 1998 and 2017. All participants had a nonstimulated thyroglobulin level of less than 1 ng/mL, no interfering antithyroglobulin antibodies and no suspicious findings on postoperative neck ultrasounds.
Follow-up ultrasound scans were classified as suspicious, indeterminate or normal based on the features found on the thyroid nodules. To be classified under normal findings, individuals must have had two consecutive negative ultrasounds.
There were 93 adults in the study cohort (86% women; median age, 49 years) with 49 having low-risk papillary thyroid cancer and 44 intermediate-risk cancer. In the low-risk group, 37 had an excellent response to treatment, three had a biochemical incomplete response and nine an indeterminate response. Two individuals in the low-risk group with an initial excellent response had a recurrence of cancer. In the intermediate-risk cohort, 21 had an excellent response to treatment, four had a biochemical incomplete response and 19 had an indeterminate response. Three participants in the intermediate-risk group had a recurrence of cancer; two had an initial excellent response to treatment and one an initial indeterminate response.
Five individuals in the full study cohort developed suspicious ultrasound findings after a median follow-up of 2.5 years. The five participants had a median of seven neck ultrasounds during a median follow-up period of 7.3 years. All five individuals with suspicious findings had small-volume disease on the neck ultrasounds and did not meet ATA’s criteria for future intervention.
Of the remaining participants, 19 developed indeterminate features on a median of five neck ultrasounds during a median follow-up period of 4 years. Structural damage was not found during follow-up investigations, indicating nonactionable findings. The remaining 69 participants had normal neck ultrasounds during a median follow-up period of 5.8 years. A median of three ultrasounds were done during follow-up.
“Continued long-term follow-up with aggressive ultrasounds in low- to intermediate-risk patients with an excellent response to therapy has the potential to cause more harm than good,” researchers wrote. “Therefore, the frequency and timing of routine neck surveillance should be tailored according to risk of recurrence and response to treatment. After 5 years of follow-up, we no longer recommend routine use of screening ultrasonography in low- to intermediate-risk patients demonstrating an excellent response to therapy.”
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