Neoadjuvant chemotherapy modifies thyroid function in postmenopausal but not premenopausal women with breast cancer

Experimental models have described several intracellular and extracellular effects of thyroid hormones, which contribute differently to the development and progression of breast cancer. In women with breast cancer, an association between elevated levels of thyroxin (T4) has been described, regardless of their pre- or post- menopausal hormonal status.  AIM: Here we determine thyroid function in pre- and postmenopausal women with breast cancer treated or not with neoadjuvant chemotherapy (NCh) by assaying circulating TSH and free T4 (fT4) levels. Comparisons were made with control premenopausal women with regular menstrual periods and postmenopausal women with spontaneous menopause for at least one year.  MATERIAL AND METHODS: Samples from patients treated with NCh were obtained after completion of chemotherapy treatment and in parallel to samples from patients not treated with NCh and control volunteers. TSH and fT4 levels TSH levels were measured by paramagnetic-beads based chemiluminescent immunoassay.  RESULTS: We have observed an increase in serum TSH and fT4 levels in both pre- and postmenopausal women with breast cancer treated or not with neoadjuvant chemotherapy. However, postmenopausal women treated with NCh increased to a lesser extent their levels of fT4. Nevertheless, as a whole, our results suggest an increased thyroid function in pre- and post- menopausal women with breast cancer.  CONCLUSION: The monitoring of the thyroid hormone profile takes on special relevance in women with breast cancer, as well as their hormonal status, in relation to tumor progression and the effectiveness of chemotherapy treatment.