Clinical Thyroidology® for the Public
Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID CANCER
Should I take extra thyroid hormone for my thyroid cancer?
BACKGROUND
Thyroid cancer is common. Fortunately, most people do well and the prognosis is excellent. Most patients are treated with thyroid surgery, after which they need to take thyroid hormone pills. For patients with a low risk of thyroid cancer returning (cancer recurrence), thyroid hormone pills were usually adjusted to keep TSH levels in the normal range.
For many years, thyroid cancer patients that were at intermediate or high risk of thyroid cancer recurrence were treated with extra thyroid hormone to get their TSH levels below the normal range. The theory behind the practice of prescribing extra thyroid hormone to decrease TSH levels was that TSH levels that were normal or slightly high would cause any remaining cancer cells to grow. Indeed, the 2015 American Thyroid Association thyroid cancer guidelines recommended to keep the TSH goal <0.1 for cancers that were high risk of recurrence and 0.1-0.5 for cancers that were intermediate risk of recurrence. However, more recent studies have investigated whether giving extra thyroid hormone to keep the TSH below normal improves thyroid cancer patients’ lifespan.
The goal of this study is to examine the effect of extra thyroid hormone on the lifespan of thyroid cancer patients at intermediate and high risk of recurrence, as well as the bad effects of giving extra thyroid hormone replacement.
THE FULL ARTICLE TITLE
Gubbi S, et al. The effect of thyrotropin suppression on survival outcomes in patients with differentiated thyroid cancer: a systematic review and meta-analysis. Thyroid 2024;34(6):674–686.
SUMMARY OF THE STUDY
Adults above the age of 18 who had intermediate and high risk of recurrence thyroid cancer were followed for 5-40 years after their diagnoses depending on the research project. In the nine research projects that were studied between 1996-2019, patients were given extra thyroid hormone to lower the TSH according to the 2015 American Thyroid Association guidelines for thyroid cancer. Patients whose TSH levels were kept below the normal range (any value below 0.5 mIU/L) were compared to those patients whose TSH levels were kept normal (above mIU/L) with levothyroxine.
When more than 3,500 patients were studied, the lifespan and time without any worsening of the thyroid cancer were not different between patients with a low TSH and those with a normal TSH. When 1,294 patients were studied through two studies, there was a higher chance of having a heart or bone problem in patients who had a low TSH.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that there is no better disease control or life span improvement when extra thyroid hormone supplementation is given to patients who have intermediate and high risk of recurrence thyroid cancers. There can be heart and bone damage from taking too much thyroid hormone. Therefore, the 2025 American Thyroid Association Thyroid Cancer guidelines support TSH goals that are mostly normal depending on the patient’s response to their thyroid cancer therapy. In addition, TSH goals are re-evaluated depending on if the patient’s response to therapy changes based on labs and imaging. These data suggest that unless a patient has distant spread of the thyroid cancer to the lungs or bones, keeping the TSH level normal might be more beneficial.
— Pinar Smith, MD
ATA RESOURCES
Hypothyroidism (Underactive): https://www.thyroid.org/hypothyroidism/
Thyroid Cancer (Papillary and Follicular): https://www.thyroid.org/thyroid-cancer/
ABBREVIATIONS & DEFINITIONS
Hypothyroidism: a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone. Treatment requires taking thyroid hormone pills.
Thyroid cancer: the most common type of thyroid cancer, includes papillary, follicular and oncocytic thyroid cancer.
Thyroid hormone therapy: patients with hypothyroidism are most often treated with Levothyroxine in order to return their thyroid hormone levels to normal. Replacement therapy means the goal is a TSH in the normal range and is the usual therapy. Suppressive therapy means that the goal is a TSH below the normal range and is used in thyroid cancer patients to prevent growth of any remaining cancer cells.
TSH: thyroid stimulating hormone — produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.
Pituitary gland: this endocrine gland sits at the base of the brain and secretes hormones that control thyroid and adrenal function, growth and reproduction. The pituitary gland secretes TSH to control thyroid function.
Cancer metastasis: spread of the cancer from the initial organ where it developed to other organs, such as the lungs and bone.
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