Thyroid hormone receptors in human breast cancer: effect of thyroxine administration

The present study was designed to establish the presence and pharmacological properties of the nuclear triiodothyronine receptors (T3R) (binding capacity, affinity and number of sites) in human breast cancer samples as well as the effects on them of thyroid hormone administration (T4). A computerized Scatchard plot analysis was designed to resolve the exponential curves in order to estimate the real number of T3R. T3R was present in 83% of the patients studied. In the thyroxine treated group, the number of nuclear T3R increased in the postmenopausal women, and may decrease in the premenopausal group, compared with the control group. These results suggest that T3R and thyroid hormone may play a role in breast cancer growth regulation; they also suggest that the T3R could open up the possibility of the classification of patients (as for ER and PgR), and consequently of new therapeutic trials.