Sonographically Estimated Risks of Malignancy for Thyroid Nodules Computed with Five Standard Classification Systems:...

Area of Science:

• Endocrinology
• Radiology
• Oncology

Background:

• Over 50% of thyroid nodules are benign or low-suspicion.
• Current surveillance relies on malignancy risk estimates from ultrasonographic classification systems like TIRADS.
• Longitudinal evaluation of risk estimate stability is needed.

Purpose of the Study:

• To assess the temporal stability of malignancy risk estimates for benign thyroid nodules using five common classification systems.
• To determine if changes in risk class during follow-up predict malignancy.

Main Methods:

• A longitudinal study re-analyzed data from 232 patients with 432 baseline benign thyroid nodules and 122 new nodules at 5-year follow-up.
• Malignancy risk was calculated using AACE/ACE/AIUM, ACR TIRADS, ATA 2015, EU-TIRADS, and K-TIRADS guidelines.
• Risk class changes and biopsy indications were evaluated over the 5-year interval.

Main Results:

• Risk class increased for 13.2-29.4% of original nodules over 5 years.
• Few nodules (6.3-8.3%) met cytology criteria at 5-year follow-up if not initially indicated.
• Only 3.3-6.6% of new nodules required biopsy based on follow-up risk estimates.
• No cancers were diagnosed in the study cohort.

Conclusions:

• Ultrasound-based risk classifications for benign thyroid nodules demonstrate good temporal stability.
• Changes in risk class requiring biopsy are infrequent.
• New nodule development is common, but most are low-risk, supporting less intensive surveillance protocols for benign thyroid nodules.