The following is a summary of “Malignancy Risk of Follicular Neoplasm (Bethesda IV) With Variable Cutoffs of Tumor Size: A Systemic Review and Meta-Analysis,” published in the May 2024 issue of Endocrinology by Cho, et al.

Determining whether to proceed with diagnostic lobectomy for follicular neoplasms (FN) diagnosed via fine needle aspiration presents a clinical challenge due to uncertainty regarding the appropriate size cutoff for recommending surgery. For a meta-analysis, researchers sought to investigate whether an optimal size cutoff existed for advising surgery for thyroid nodules diagnosed as FN by fine needle aspiration.

The Ovid-Medline, EMBASE, Cochrane, and KoreaMed databases were systematically searched for studies reporting the malignancy rate of FN or suspicious for FN (FN/SFN) nodules based on tumor size. Search terms included “fine needle aspiration,” “follicular neoplasm,” “lobectomy,” “surgery,” and “thyroidectomy.”

About 14 observational studies encompassing 2016 FN/SFN nodules with postsurgical pathologic reports were included. The pooled analysis revealed the following malignancy risk odds ratios (OR) based on tumor size cutoffs: 2.29 (95% CI, 1.68-3.11) for ≥4 cm (9 studies), 2.39 (95% CI, 1.45-3.95) for ≥3 cm (3 studies), and 1.81 (95% CI, 0.94-3.50) for ≥2 cm (5 studies). In the sensitivity analysis, however, tumors ≥2 cm also showed a higher risk (OR 2.43; 95% CI, 1.54-3.82). Summary receiver operating characteristic (sROC) curves indicated that the cutoff of 4 cm had the highest summary area under the curve (sAUC, 0.645) compared to other cutoffs (sAUC, 0.58 with 2 cm, and 0.62 with 3 cm).

While the risk of malignancy increases with tumor size, significant risk persists across all tumor sizes. No specific cutoff limit can be recommended as a definitive parameter for diagnostic surgery in Bethesda IV thyroid nodules.

Reference: academic.oup.com/jcem/article-abstract/109/5/1383/7479149