Deescalating Follow-up after Hemithyroidectomy for Patients with Low-risk Papillary Thyroid Microcarcinoma

Importance: Structural recurrent disease (RD) after surgical treatment of papillary thyroid microcarcinoma (mPTC) is rare. We hypothesized that the RD rate after hemithyroidectomy in low-risk patients with mPTC is low. Objective: To assess the occurrence of RD in Dutch patients with mPTC who received surgical treatment according to the Dutch guidelines. Design, Setting, and Participants: This nationwide retrospective cohort study included all patients who had undergone surgery with a diagnosis of cN0/cNx mPTC in the Netherlands between January 2000 and December 2020 were identified from the Netherlands Cancer Registry database. Patients with preoperative lymph node metastases were excluded. Two groups were defined: group 1 (incidental), mPTC in pathology report after thyroid surgery for another indication; and group 2 (nonincidental), patients with a preoperative highly suspect thyroid nodule (Bethesda 5) or proven mPTC (Bethesda 6). Dutch guidelines state that a hemithyroidectomy is sufficient in patients with unifocal, intrathyroidal mPTC. Main Outcomes and Measures: The occurrence of RD in patients with low-risk mPTC after hemithyroidectomy. Results: In total, 1636 patients with mPTC were included. Patients had a median (IQR) follow-up time of 71 (32-118) months. Median (IQR) age at time of diagnosis was 51 (41-61) years and 1292 (79.0%) were women. Overall, RD after initial treatment was seen in 25 patients (1.5%). The median (IQR) time to RD was 8.2 (3.6-16.5) months and 22 of the 25 (88%) patients developed RD within 2 years. Recurrent disease was not significantly different between both groups (group 1, n = 15 [1.3%]; group 2, n = 10 [2.1%]; difference, 0.8%; 95% CI, -0.5% to 2.5%). Of the 484 patients with nonincidental mPTC (group 2), 246 (50.8%) patients were treated with a hemithyroidectomy and follow-up in accordance with Dutch guidelines. Lymph node metastases were found in 1 of 246 (0.4%) patients after hemithyreoidectomy, and new mPTC in the contralateral thyroid was detected in 3 of 246 (1.2%) patients. Median (IQR) follow-up of this patient group was 37 (18-71) months. The 10-year probability of RD was 1.3% for patients without vascular invasion and 24.4% for patients with vascular invasion. Conclusions and Relevance: This nationwide cohort study found that overall, RD after hemithyroidectomy for patients with low-risk mPTC was rare (<2%). Based on these results, it seems reasonable to deescalate follow-up of patients with low-risk mPTC without vascular invasion after hemithyroidectomy. From a health care perspective, deescalation of follow-up may contribute to increased sustainability and accessibility to health care, both large challenges for the future..