RELATIONSHIP BETWEEN BREAST-CANCER AND THYROID-DISEASE - RELEVANCE OFAUTOIMMUNE THYROID-DISORDERS IN BREAST MALIGNANCY

The relationship between thyroid dysfunction and breast cancer (BC) is debated. To clarify this controversial issue, a prospective study on thyroid function in BC was performed. The prevalence of thyroid diseas e was examined in 102 consecutive BC patients with ductal infiltrating carcinoma after surgery and before starting any chemohormonal or x-ra y therapy and in 100 age-matched control healthy women Living in the s ame borderline iodine-sufficient geographic area. All subjects were su bmitted to clinical ultrasound thyroid evaluation and serum free T-4, free T-3, TSH, thyroperoxidase antibody, and thyroglobulin antibody de termination. Fine needle aspiration was performed in all thyroid nodul es. Estrogen and progesterone receptors (ER and PR, respectively) were assayed in 92 and 55 BC specimens, respectively. The overall prevalen ce of thyroid disease was 47 in 102 (46%) in BC patients and 14 in 100 (14%) in controls (P < 0.0001). The prevalence of nontoxic goiter was 27.4% in BC patients and 11% in controls (P = 0.003). Hashimoto's thy roiditis was found in 13.7% of BC patients and in only 2% of the contr ols (P < 0.005). Other thyroid disorders found in the BC group include d 2 cases of Graves' disease, 2 of thyroid carcinoma, and 1 of subacut e thyroiditis, whereas in the control group only 1 case of Graves' dis ease and none of the other disorders were found. Mean free T-3, free T -4, and TSH concentrations showed no difference between BC patients an d controls. The prevalence of thyroperoxidase antibody was higher in B C patients than in controls (23.5% vs. 8%; P < 0.005), whereas the pre valence of thyroglobulin antibody was not different. In BC patients th e presence of thyroid antibodies was more frequently associated with c linically detectable autoimmune thyroiditis (14 of 26, 51.8%; P = 0.03 ) and was more common in the younger group. The positivity of ER was f ound in 51 of 92 (55.43%) and that of PR was found in 26 of 55 (47.27% ) BC specimens. No relationship was found among ER, PR status, and the presence of serum thyroid antibodies. In conclusion, 1) the present s tudy provides evidence that the overall prevalence of thyroid disorder s is increased in patients with breast cancer; and 2) thyroid autoimmu ne disorders, especially Hashimoto's thyroiditis, account to a large e xtent for the increased prevalence of thyroid disease in patients with breast cancer. This feature is independent from the ER and PR status of the primary tumor. The present findings call attention to the usefu lness of screening for thyroid disease in any patient with breast canc er.