Intermediate-Risk Papillary Thyroid Cancer: Not Everyone Needs Radioactive Iodine

Intermediate-risk papillary thyroid carcinoma (PTC) accounts for 40%-60% of newly diagnosed PTC and comprises a heterogeneous group with variable recurrence risk. The benefit of postoperative radioactive iodine (RAI) remains uncertain.

To describe features, response-to-therapy outcomes, and ATA 2025 recurrence-risk redistribution in patients with ATA 2015 intermediate-risk PTC managed without adjuvant RAI.

Retrospective cohort study.

Adults (≥ 18 years) with ATA 2015 intermediate-risk PTC treated with total thyroidectomy (TT) or thyroid lobectomy (TL), with/without lymph node dissection, and followed for ≥ 1 year were included. Omission of postoperative RAI was based on histopathology, cervical ultrasound (US), serum thyroglobulin (Tg), and anti-thyroglobulin antibodies (TgAb) measured within 6 months postoperatively. TL patients required negative US. TT patients required negative US plus Tg < 1 ng/mL if TgAb-negative, or stable/declining TgAb if positive. Response to therapy was assessed using ATA 2015 dynamic risk stratification and reassessed with ATA 2025 criteria.

Ninety-nine patients were included; 84 (84.8%) were women, the mean age was 40.2 ± 13.3 years, and the median follow-up was 4.8 years. Microscopic extrathyroidal extension was present in 51 (51.5%), lymph node metastases in 37 (37.4%), and extranodal extension in 4 (4.0%). By ATA 2015, 67 (67.7%) had an excellent response and 32 (32.3%) an indeterminate response; no incomplete responses or structural recurrences occurred. ATA 2025 reclassified 3 (3.0%) as low risk, 39 (39.4%) as low-intermediate, 52 (52.5%) as high-intermediate, and 5 (5.1%) as high risk.

Selected intermediate-risk PTC patients managed without adjuvant RAI had excellent mid-term outcomes, supporting a risk-adapted de-escalation strategy.