• ATA guidelines
• cancer
• carcinoma
• intraoperative frozen section
• lobectomy
• papillary
• thyroid
• thyroidectomy

Background: The extent of surgery for low-risk papillary thyroid cancer (PTC) remains controversial. Current guidelines endorse lobectomy as initial surgical approach. However, if high risk features (HRFs), such as aggressive subtypes, extrathyroidal extension, lymph node metastases or vascular invasion, are found in final histology a completion thyroidectomy (Ctx) may be necessary to facilitate radioactive iodine (RAI) therapy. Nevertheless, the need for completion varies considerably among medical teams due to different approaches in RAI use. Although generally safe Ctx is often challenging, adds costs and carries risks for complications. The aim of this study is to assess the effectiveness of intraoperative frozen section examination (IFS) in identifying HRFs that indicate the need for total thyroidectomy thereby evaluating its potential role in modulating the extent of surgery in patients with low-risk PTC.
Methods: The study included patients with localized low-risk PTC and was conducted in two phases. A retrospective analysis to assess HRFs and Ctx rates, and a prospective study including patients scheduled for lobectomy with IFS use. The performance of IFS in detecting HRFs was compared with final histology to evaluate its potential role in reducing the need for completion thyroidectomy.
Results: A total of 103 patients (Group A) underwent lobectomy with IFS, while 433 patients retrospectively met criteria for lobectomy according to ATA guidelines. Of these, 105 (Group B) underwent lobectomy as their initial treatment. In final pathology, 47.3% of patients eligible for lobectomy showed HRFs warranting completion thyroidectomy. Among those who underwent lobectomy 17 patients (16%) required completion surgery. The likelihood of completion increased with multiple HRFs. In the prospective phase, IFS identified aggressive subtypes in most cases with good sensitivity (70%) and excellent specificity (100%), though it was less effective in detecting ETE and VI. Overall, IFS provided valuable predictive data, potentially reducing the need for additional surgery.
Conclusion: IFS demonstrated good sensitivity and specificity in identifying aggressive variants of PTC. It can potentially be valuable in guiding the extent of surgery for low-risk PTC especially in centers where RAI is used more aggressively. However, its cost-effectiveness may be limited in settings where RAI is selectively used.