Non-Operative, Active Surveillance of Larger Malignant and Suspicious Thyroid Nodules.

Abstract

Active surveillance for papillary thyroid cancer (PTC) meeting criteria for surgical resection is uncommon. Which patients may prove reasonable candidates for this approach is not well defined. To examine the feasibility and safety of active surveillance for patients with known or suspected intrathyroidal PTC up to 4cm in diameter. Retrospective review of all consecutive patients who underwent non-operative active surveillance of suspicious or malignant thyroid nodules over a 20-year period from 2001-2021. We included patients with an initial US-FNA confirming either: a) Bethesda 5 or 6 cytology or, b) a "suspicious" AFIRMA molecular test. The primary outcomes and measures included the rate of adverse oncologic outcomes (mortality and recurrence), as well as the cumulative incidence of size/volume growth. Sixty-nine patients were followed with active surveillance for 1 year or longer (average 55 months), with 26 patients (38%) having nodules ≥ 2 cm. No patients were found to develop new incident occurrence of lymph node or distant metastasis. One patient however, demonstrated concern for progression to a dedifferentiated cancer on repeat core biopsy 17 years after initial start non-operative selection. 21% of patients had an increase in maximum diameter more than 3 mm, and volume increase ≥50% was noted in 25% of patients. Thirteen patients ultimately underwent delayed (rescue) surgery, and no disease recurrence was noted after such treatment. Age and initial nodule size were not predictors of nodule growth. These data expand consideration of active surveillance of papillary thyroid carcinoma in select patients with intrathyroidal suspected malignancy >1cm in diameter. Rescue surgery, if required at a later timepoint, appears effective.