Thyroid Cancer: Individualized Follow-Up Curtails Unnecessary Tests

“Less is more” is the new mantra of the American Thyroid Association (ATA) in its updated guidelines on thyroid cancer surveillance. In patients who respond well to treatment, an anxiety-provoking extensive workup at follow-up visits may not be needed.^1,2 The ATA’s stance is to vary the follow-up strategy based on a patient’s histotype, response to initial treatment, and risk for recurrence.¹

Why Less Is More in Testing

Although it is common for differentiated thyroid cancer (DTC) to recur, it has a low mortality rate.³ Most of the recurrences found on routine surveillance are residual cancer that initial diagnostics failed to detect or that were not resected during initial thyroid surgery.

Ultrasound and serum thyroglobulin testing are the recommended surveillance measures in patients with a low to intermediate risk for recurrence.³ For DTC, the risk for recurrence is 3% to 13% in low-risk individuals, 21% to 36% in individuals with intermediate risk, and 68% in individuals at the highest risk.³

“I hope that clinicians are judicious with the imaging studies given that many times the anatomical lesions may not imply clinically significant recurrent disease and overall, the clinical course and prognosis is generally good,” said Prasanna Santhanam, MBBS, MD, assistant professor in the division of endocrinology, metabolism, and diabetes at the Johns Hopkins University School of Medicine in Baltimore, Maryland. “The diagnostic criteria and the staging are similar, but the approach has changed to somewhat less aggressive, less intensive measures. They should follow the recommendations of the  2015 ATA guidelines while exercising some sound clinical judgement.”

“Noninvasive” Does Not Mean “Risk Free”

Thyroid cancer variants like noninvasive follicular thyroid neoplasm with papillary-like features (NIFTP), which were thought to be low risk, merit closer examination.⁴ Antoine Eskander, MD, ScM, FRCSC, assistant professor in the department of otolaryngology from the University of Toronto in Ontario, Canada, and colleagues, cautioned clinicians not to become complacent because of the benign-sounding name. In their retrospective study of 725 cases of well-differentiated thyroid cancer, 318 were found to be of the NIFTP type.⁴ During the median 15.3-year follow-up, 9.4% of individuals who had NIFTP had a recurrence.⁴

“I hope clinicians realize that NIFTP is not a benign disease despite the awkward name change,” said Dr Eskander. “The diagnosis is challenging, particularly in the real-world setting, and therefore patients should be managed similar to patients with encapsulated follicular variant of papillary thyroid cancer until data on this topic has matured.”

Reduce Unnecessary Testing, Reduce Stress

Manijeh Mohammadi, MD, from the Sunnybrook Health Sciences Center and University of Toronto in Ontario, Canada, and colleagues, revisited the 2015 ATA guidelines to determine whether a checklist based on features of malignant nodules could reduce the number of fine needle aspirations.⁵ The retrospective study sampled 425 ultrasound scans of thyroid nodules and found 32 (approximately 8%) to be malignant;⁵ these tended to be solid and had greater cervical lymph node involvement than benign nodules. Use of the checklist had a 9% positive predictive value, 97.5% negative predictive value, 96.8% sensitivity, and 11.4% specificity for malignant cytologic diagnosis.⁵ Moreover, the researchers found that no single ultrasound feature could be used to determine whether or not a nodule was malignant.⁵