Active Surveillance in Adults with Low-Risk Papillary Thyroid Microcarcinomas: A Prospective Study

The acceptance and results of active surveillance in patients with low-risk papillary thyroid microcarcinomas (PTMC) are unknown in populations other than the Japanese population. This was the objective of the present prospective study. We selected patients ≥20 years who had thyroid nodules ≤1.2 cm with intermediate or high suspicion for malignancy on ultrasonography (US), not located near the recurrent laryngeal nerve and without extrathyroidal invasion or apparent lymph node metastases, whose cytology was suspicious (Bethesda V) or diagnostic (Bethesda VI) of papillary thyroid carcinoma. Patients who opted for active surveillance were followed up by biannual US. Fifteen patients (18.7%) readily opted for surgery and 12 (15%) for active surveillance. Fifty-three patients (66.2%) delegated the decision or wished to know the doctor's preference before deciding. After the doctor had declared his/her preference for active surveillance, 50 patients decided to have this management and three to have surgery. Only 1/70 patients exhibited tumor progression (growth associated with a suspicion of extrathyroidal invasion) after 30 months of follow-up. Two patients decided to have surgery during follow-up, although the indication was not defined by the study. A>50% reduction in tumor volume was observed in three patients. The study shows that active surveillance can be well accepted if doctors were convinced that it is the best option for patients with low-risk PTMC. At least the short-term results reproduced those observed in other populations, with tumor progression being uncommon.