Immunohistochemical studies of estrogen receptors in 351 benign and malignant thyroid specimens

It is well recognized that the pathogenesis of thyroid diseases is complex and different factors such as heredity, iodine deficiency, sex, age, radiation therapy in childhood, growth stimulating antibodies, and other epithelial growth factors can influence it. Epidemiological features of thyroid tumors and experimental evidences suggest that female sex hormones may exert effects on this gland and its neoplasms. This possibility was addressed by investigating the expression of estrogen receptor protein in 351 thyroid lesions. 351 cases of human thyroid tissues comprising 130 nodular goiters and 221 neoplastic lesions were used for the present immunohistochemical study of estrogen receptor expression. Positive control was estrogen receptor positive breast cancer tissues. The prevalence of estrogen receptor positive cases was 24% (31/130) for nodular goiters, 22% (8/37) for follicular adenomas, 11% (2/18) for follicular carcinomas, 31% (37/119) for papillary carcinomas, 0% (0/35) for medullary carcinomas, and 0% (0/12) for undifferentiated carcinomas. The prevalence of estrogen receptor positivity is more in well differentiated thyroid lesions. It is in parallel with other investigations. Estrogen receptor reactivity does not significantly differ between females and males, different age groups and does not correlate with lymph node status and vascular or capsular invasion. The relative high estrogen receptor positivity in goiters, follicular adenomas and papillary carcinomas and strong statistical association between estrogen receptor positivity and papillary carcinomas (P<0.0005), suggests that the incidence of estrogen receptor reactivity tends to increase with better differentiation of thyroid lesions. The use of these findings in treating the patients merits more clinical investigations.