Related Experiment Videos
Thyroid function in postmenopausal breast cancer patients treated with tamoxifen
G B Anker1, P E Lønning, A Aakvaag
1Department of Oncology, Haukeland University Hospital, Bergen, Norway.
Summary
Tamoxifen treatment in postmenopausal women with breast cancer significantly alters thyroid function. It suppresses free triiodothyronine (FT3) and free thyroxine (FT4) levels while increasing thyroid-binding globulin (TBG) and thyroglobulin (TG).
Area of Science:
- Endocrinology
- Oncology
- Pharmacology
Background:
- Tamoxifen is a widely used selective estrogen receptor modulator (SERM) for breast cancer treatment.
- Potential impacts of tamoxifen on endocrine function, particularly thyroid hormones, require thorough investigation.
Purpose of the Study:
- To evaluate the effects of tamoxifen on thyroid function in postmenopausal women with breast cancer.
Main Methods:
- Thyroid function tests were performed on 26 postmenopausal women with breast cancer.
- Measurements were taken before and at various intervals during tamoxifen treatment.
Main Results:
- Tamoxifen significantly suppressed plasma free triiodothyronine (FT3) and free thyroxine (FT4) levels (p < 0.005).
- Elevated plasma concentrations of thyroid-binding globulin (TBG) (p < 0.005) and thyroglobulin (TG) (p < 0.025) were observed.
- Plasma TSH increased significantly after 1 year of treatment (p < 0.025).
- Changes became significant generally after 6 months of treatment.
Conclusions:
- Tamoxifen influences thyroid hormone levels by modulating plasma TBG and potentially interfering with thyroid hormone synthesis or secretion.
- Reduced bioavailability of T4 and T3 is suggested by the observed hormonal changes.