BACKGROUND
Thyroid cancer is common. Fortunately, the prognosis is excellent as we have very effective treatments, including surgery, radioactive iodine therapy and thyroid hormone suppression. Years ago, most patients got all 3 of these treatments. However, as more studies have come out allowing better identification of patients that are at low risk of the thyroid cancer, these treatment options have changed. Now lobectomy (remove of the lobe that contains the cancer) is becoming more common as opposed to removal of entire thyroid (total thyroidectomy). Radioactive iodine therapy is now being reserved for patients at highest risk for thyroid cancer recurrence. This paper now addresses the need for thyroid hormone suppression after surgery.

Thyroid hormone suppression means adjusting the thyroid hormone dose to keep TSH levels very low. Keeping TSH levels low may help prevent the cancer from coming back, but too much thyroid hormone can cause heart problems, bone loss, and other side effects. Doctors have debated how low TSH should be for different risk levels of thyroid cancer. This study looked at whether stricter TSH suppression really lowers the chance of thyroid cancer coming back.

THE FULL ARTICLE TITLE
Cho YY et al. TSH cut-offs and recurrence risk in differentiated thyroid carcinomas: a systematic review and meta-analysis. J Clin Endocrinol Metab. 2025. Epub 2025 Aug 14:dgaf463; doi: 10.1210/clinem/dgaf463. PMID: 40811629.

SUMMARY OF THE STUDY
Researchers looked at 9 studies with over 5,000 people who had thyroid cancer. They compared cancer recurrence rates in patients who kept their TSH levels very low (<0.1), somewhat low (0.1–0.5), or closer to normal (up to 2.0).

They also looked at whether patients were low-, medium-, or high-risk for the cancer returning, and whether they had cancer that had spread to other parts of the body (metastases).

In the primary analysis, cancer recurrence risk did not differ significantly at any TSH cutoff. When stratified by ATA risk, no significant differences were observed for low-risk or high-risk patients. Data for intermediaterisk patients were too limited for analysis, with only a single study available. Notably, patients with spread of the cancer outside of the neck had significantly higher recurrence risk when TSH was maintained at ≥0.1 mIU/L versus at <0.1 mIU/L.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The study supports new 2025 guidelines that say most people with thyroid cancer do not need very strong TSH suppression for life. Instead, doctors can adjust thyroid hormone doses based on how patients respond to treatment and how they are feeling. This approach may help prevent side effects while keeping the cancer from returning.

Keeping TSH extremely low is not necessary for most thyroid cancer survivors. Only people with cancer that has spread far from the thyroid might still need stronger suppression. Patients can feel reassured that their treatment can be personalized. Many people can take less thyroid hormone and still stay safe, reducing risks to their heart, bones, and quality of life.

— Maria Brito, MD, ECNU

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