In a nutshell
The authors aimed to assess whether chemotherapy has an impact on thyroid function.
Some background
The thyroid is an endocrine gland (tissue that releases hormones) found in the neck. It controls how quickly the body uses energy used in the body, how the body reacts to other hormones and makes proteins.
Thyroid hormones can have enhancing effects on breast cancer tumor growth. Inversely, hypothyroid (under-active thyroids) patients may be 'protected' from breast cancer. This indicates a link between thyroid hormones and breast cancer.
To date, the interaction between thyroid hormones and chemotherapy have not been well studied.
Methods & findings
The aim of the study was to determine whether chemotherapy had effects on thyroid function. The levels of free thyroxine and hyroid stimulating hormone (TSH), two thyroid hormones, were analysed pre- and post-treatment.
A total of 38 women with human epidermal growth factor receptor 2 negative (HER2-) breast cancer, of whom 33 were hormone receptor positive (HR+; presence of either estrogen receptor or progesterone receptor proteins on cancer cells) with no previous thyroid problems were evaluated. 18 of the patients were allocated to a course of chemotherapy before surgery with zoledronic acid (Zometa; used to prevent bone weakening associated with chemotherapy), 20 patients received chemotherapy before surgery without zoledronic acid.
During chemotherapy, free thyroxine levels decreased while TSH levels increased. Greater reductions in free thyroxine was associated an increased risk of experiencing nausea, vomiting and nerve damage compared to lesser reductions. In simple analyses, higher levels of TSH were associated with a better chance of complete cancer disappearance.
Overall, 12.5% of HR+ breast cancer patients and 40% of the triple-negative patients (cancer cells that are negative for both HR+ and HER2) achieved complete disappearance of the cancer.
The bottom line
The authors concluded that chemotherapy affects thyroid functions during breast cancer treatment.
The fine print
This study included a very small group of patients.
What’s next?
Discuss your treatment with your doctor if you have existing thyroid problems.
Published By :
Breast Cancer Research and Treatment
Date :
Jan 06, 2015
We have a 58 year old lady…post adjuvant ch TSH of 150
T3 normal
T4 low.
High TSH is suggestive of cure but will adding thyroxine to bring TSH to normal and to reduce symptoms increase chances of recurrence
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