Thyroid function might decrease after adjuvant chemotherapy in postmenopausal women with early breast cancer

Djordje Marina; Kristian Buch-Larsen; Linn Gillberg; Mads Andersen; Michael Andersson; Rasmussen AEse Krogh; Peter Schwarz

doi:10.1530/endoabs.99.P581

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Endocrine Abstracts (2024) 99 P581 | DOI: 10.1530/endoabs.99.P581

ECE2024 Poster Presentations Thyroid (58 abstracts)

Thyroid function might decrease after adjuvant chemotherapy in postmenopausal women with early breast cancer

Djordje Marina ¹ , Kristian Buch-Larsen ² , Linn Gillberg ³ , Mads Andersen ⁴ , Michael Andersson ¹ , Æse Krogh Rasmussen ¹ & Peter Schwarz ¹

Err

Author affiliations

¹Rigshopitalet, Department of Endocrinology, Copenhagen, Denmark; ²Rigshospitalet, Department of Endocrinology, København, Denmark; ³University of Copenhagen Panum and Mærsk Tower, Department of Biomedical Sciences, København, Denmark; ⁴Rigshospitalet, Department of Oncology, Centre for Cancer and Organ Diseases, København, Denmark

Objective: Adjuvant chemotherapy is often indicated in patients diagnosed with early breast cancer. Weight gain is one of the observed side effects of both chemotherapy and other cancer treatments, however, the mechanism is not well-described. In this study, we aimed to assess thyroid function before- and after the course of chemotherapy for early breast cancer.

Methods: This study is a 5-year prospective cohort study of patients diagnosed with early breast cancer. The main outcome was the thyroid function and body weight before and after completing chemotherapy. Secondary outcomes were the presence of thyroid autoantibodies and treatment radiation dosage. We included 72 patients. All patients received adjuvant chemotherapy, whereas 59 patients also received supraclavicular locoregional radiotherapy.

Results: At an average of 86 days after chemotherapy, we observed an increase in thyroid-stimulating hormone (P=0.03) and a decrease in free-thyroxine (P=0.0006), whereas no significant weight change. The prevalence of autoimmune thyroiditis was low, and we found no statistically significant difference in the thyroid function of women treated vs not treated with locoregional radiotherapy.

Conclusion: The present study suggests that thyroid function might be decreased in women with early breast cancer after adjuvant chemotherapy. The decrease in thyroid function was neither related to autoimmunity, low T3 syndrome, radiotherapy, nor high-dose corticosteroids, and an effect of adjuvant chemotherapy is suggested. It is still unknown whether the observed decrease in thyroid function is transient or permanent, and further studies with a longer follow-up of thyroid hormones are needed to observe the clinical significance of these changes.