JMIR Publications

ABSTRACT

Background:

Surgeons often face challenges in distinguishing between benign and malignant follicular thyroid neoplasms (FTNs), particularly for small tumors, until diagnostic surgery is performed.

Objective:

This study aimed to identify the size-specific predictors for malignancy risk of FTNs preoperatively.

Methods:

A retrospective cohort study was conducted at Peking University Third Hospital in Beijing, China, from 2012 to 2023. Patients with a postoperative pathological diagnosis of follicular thyroid adenoma (FTA) or carcinoma (FTC) were included. FTNs were classified into small- and large-sized categories based on the cutoff value of tumor diameter derived from spline regression, which indicated the turning point of malignancy risk. We identified the 5 most important predictors from 22 variables including demography, sonography, and hormones, using machine learning methods. We also calculated odds ratios (OR) with 95% confidence intervals (CI) for these predictors in both small- and large-sized FTNs. To synthesize existing evidence on this topic, a literature review of clinical guidelines and research papers was conducted.

Results:

Altogether, we included 1494 FTNs, comprising 1266 FTAs and 228 FTCs. FTNs with a maximum diameter smaller than 3.0 cm were grouped as small-sized (n = 715), while those with larger diameters were categorized as large-sized (n = 779). In the small-sized group, tumors appearing macrocalcification [OR (95%CI): 2.90 (1.50, 5.60)], peripheral calcification [4.50 (1.50, 13.00)], or in younger patients [1.33 (1.05, 1.69)] showed a higher malignancy risk. In the large-sized group, tumors presenting a nodule-in-nodule appearance [3.30 (1.30,7.90)] exhibited a higher malignancy risk. In both groups, lower TSH levels [small-sized FTNs: 1.49 (1,20, 1,85); large-sized FTNs: 1.61 (1.37, 1.96)] and larger mean diameter [small-sized FTNs: 1.40 (1.10, 1.70); large-sized FTNs: 1.50 (1.20, 1.70)] were associated with the malignancy risk of FTNs. Our review identified a research gap in using tumor size thresholds as a stratification factor for assessing malignancy risk in FTNs before diagnostic surgery, which is not addressed by current clinical guidelines or existing literature.

Conclusions:

This study identified size-specific predictors for malignancy risk in FTNs, highlighting the importance of stratified prediction based on tumor size. Clinical Trial: This study has been registered publicly.