IMMUNOHISTOCHEMICAL EXPRESSION OF ESTROGEN RECEPTOR ALPHA (ERalpha) AND PROGESTERONE RECEPTOR (PR) IN PATIENTS WITH PAPILLARY THYROID CANCER

Background: Papillary thyroid cancer (PTC) prevalence is nearly 3 times higher in females than in males. This gender difference suggests that growth and progression of PTC might be influenced by female sex hormones. Objectives: To analyze the expression of both estrogen receptor (ER)-α and progesterone receptor (PR) by immunohistochemistry in 203 PTC patients. Methods: ER-α and PR expression was evaluated in paraffin-embedded tumor tissue samples of 45 males and 158 females followed up for 7.2 ± 3.7 years. Results: ER-α was expressed in 52 (25.6%) patients (41 females and 11 males) and PR in 94 (46.3%) patients (75 females and 19 males). ER-α and PR were coexpressed in 31 (15.3%) patients (27 females and 4 males). ER-α expression correlated significantly with tumor size in the whole sample (ER-α positive 22.8 ± 11.8 mm vs. ER-α negative 15.1 ± 12.4 mm; p = 0.02) and in the subgroup of women (ER-α positive 18.8 ± 12.8 mm vs. ER-α negative 14.9 ± 12.3 mm; p = 0.048). In addition, ER-α expression significantly correlated with remission of the disease. In fact, of the 192 patients followed up, 50/153 (32.7%) disease-free patients were ER-α positive, in contrast to only 3/39 (7.7%) with evidence of disease persistence/recurrence (χ2 = 8.5, p = 0.0036). PR expression was not associated with any of the parameters analyzed. Conclusions: The present study confirmed recent data indicating that ER-α and PR expression is a common finding in thyroid tumor tissue. However, in contrast to previous reports, we observed an association between ER-α expression and a more favorable outcome in PTC patients.