What is it about?

Although anti-oestrogens tamoxifen and letrozole have been used for more than a decade, less is known about the side effects of these treatments on thyroid function. Breast cancer patients gain on average 1-5 kg during the treatment with chemotherapy/anti-oestrogens, yet for unknown reasons. We performed a systematic review to examine if tamoxifen/letrozole can influence thyroid function and thereby can partly explain weight gain in patients treated for breast cancer.

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Why is it important?

Side-effects of cancer treatments can influence the quality of life. Despite great advances in cancer treatments during the last decade, less is known about treatment-related side effects and reasons for weight gain. Our findings show that tamoxifen can influence thyroid function, being the risk of subclinical hypothyroidism and probaly weight gain.


I hope this article will raise awareness on a very important issue - the side-effects of cancer treatments. Disease-free survival of breast cancer patients will still be the most important end-point, but reaching the knowledge of treatment-related side-effects can change the quality of life of people living with this condition.

Djordje Marina
Rigshospitalet, University Hospital of Copenhagen, Denmark

Read the Original

This page is a summary of: Influence of the anti‐oestrogens tamoxifen and letrozole on thyroid function in women with early and advanced breast cancer: A systematic review, Cancer Medicine, June 2022, Wiley,
DOI: 10.1002/cam4.4949.
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