SERIAL NECK ULTRASOUND IS MORE LIKELY TO IDENTIFY FALSE-POSITIVE ABNORMALITIES THAN CLINICALLY SIGNIFICANT DISEASE IN LOW-RISK PAPILLARY THYROID CANCER PATIENTS

Objective: American Thyroid Association (ATA) low-risk papillary thyroid cancer (PTC) patients without structural evidence of disease on initial posttreatment evaluation have a low risk of recurrence. Despite this, most patients undergo frequent surveillance neck ultrasound (US). The objective of the study was to evaluate the clinical utility of routine neck US in ATA low-risk PTC patients with no structural evidence of disease after their initial thyroid surgery.

Methods: We performed a retrospective review of 171 ATA low-risk PTC patients after total thyroidectomy, with or without radioactive iodine (RAI) ablation, who had a neck US without suspicious findings after therapy. The main outcome measure was a comparison of the frequency of finding false-positive US abnormalities and the frequency of identifying structural disease recurrence.

Results: Over a median follow-up of 8 years, 171 patients underwent a median of 5 neck US (range 2-17). Structural recurrence with low-volume disease (≤1 cm) was identified in 1.2% (2/171) of patients at a median of 2.8 years (range 1.6-4.1 years) after their initial diagnosis. Recurrence was associated with rising serum thyroglobulin (Tg) level in 1 of the 2 patients and was detected without signs of biochemical recurrence in the other patient. Conversely, false-positive US abnormalities were identified in 67% (114/171) of patients after therapy, leading to additional testing without identifying clinically significant disease.

Conclusion: In ATA low-risk patients without structural evidence of disease on initial surveillance evaluation, routine screening US is substantially more likely to identify false-positive results than clinically significant structural disease recurrence.