BACKGROUND
Cancer risk stratification plays a pivotal role in guiding treatment decisions, which must be tailored to individual patient characteristics. This depends on the stage of the cancer, which depends on the type of cancer and the spread of the cancer to elsewhere in the body. The main pathology staging system of cancers (AJCC/UICC) is designed to predict the risk of death from cancer. However, the excellent prognosis of differentiated thyroid cancer led to the development of additional risk stratification systems focused on cancer recurrence rather than death. The 2009 ATA cancer guidelines introduced 3 groups (low, intermediate, and high risk) to estimate the likelihood of recurrence of the cancer after the initial treatment. In 2015, the ATA guidelines, after incorporating new evidence, substantially refined and expanded this model. The 2025 guidelines expand the risk stratification groups to help identify which patients will benefit from additional treatment, such as radioactive iodine therapy.

This paper summarizes the changes in risk stratification in the 2025 ATA differentiated thyroid cancer guidelines.

THE FULL ARTICLE TITLE
Ringel MD et al. 2025 American Thyroid Association management guidelines for adult patients with differentiated thyroid cancer. Thyroid 2025;35(8):841-985.

SUMMARY OF THE STUDY
The 2025 ATA risk classification introduces several important updates compared with the 2015 system. A major role in this classification is to help identify which patients will benefit from additional treatment, such as radioactive iodine therapy.

1. The traditional three-tier model has been replaced by a four-tier classification based on the risk of thyroid cancer recurrence. This mainly divided the intermediate group into intermediate vs high risk. The current groups are:
   1. Low risk: risk of recurrence: <10%
   2. Low–intermediate risk: 10–15%
   3. Intermediate–high risk: 16–30%
   4. High risk: >30%

2. The model now clearly distinguishes recurrence behavior of thyroid cancer based on the pathology results.
   1. Papillary thyroid cancer and its subtypes most commonly present with spread to the lymph nodes in the neck, but recurrence is rare when the cancer is limited to the thyroid and completely removed.
   2. Follicular thyroid cancer and invasive encapsulated follicular variant of papillary thyroid cancer typically spread through the blood, with the extent of vascular invasion serving as one of the main risk determinants.
   3. Oncocytic thyroid cancer has a higher rate of recurrence outside of the neck and extensive vascular invasion markedly increases recurrence risk. Further, oncocytic thyroid cancer is more resistant to radioactive iodine therapy than other forms of differentiated thyroid cancer.
3. New features, such as margin involvement, multiple areas of cancer within the thyroid, cancer size, and spread outside of the thyroid have been incorporated into the 2025 classification.
4. The 2025 model emphasizes that the combination of features can have an additive effect on the overall recurrence risk. For instance, the coexistence of two low–intermediate-risk factors reclassify the cancer as being intermediate–high risk of recurrence. This underscores that the increase in the number of adverse features significantly magnifies overall risk.
5. Follicular and oncocytic thyroid cancer are now evaluated separately and extensively characterized in the 2025 guidelines

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The 2025 ATA thyroid cancer guidelines have clarified cancer recurrence risk assessment by the division of intermediate risk of recurrence cancer into either low–intermediate or intermediate–high risk and the subclassification of thyroid cancer subtypes (papillary, follicular and oncocytic). In doing so, the guidelines provide the most comprehensive set of recommendations to date to help clinicians associate a cancer’s pathologic features with a percentage range for risk of cancer recurrence after initial treatment. This risk assessment, in turn, helps patient– doctor discussions and decision-making by identifying which patients would benefit from additional therapy, such as radioactive iodine therapy.

— Alan P. Farwell, MD

Table of Contents | PDF File for Saving and Printing