Abstract
Two estrogen receptor isoforms (ER alpha and ER beta) have been characterized with variable and sometimes contrasting responses to estrogens, partially explained by different receptor signaling pathways in estrogen-sensitive tissues. This is a retrospective, descriptive, cross-sectional study, aiming to evaluate the expression pattern of ER beta, employing immunohistochemical techniques using specific monoclonal antibody for ER beta, to correlate its expression with that of ER alpha in a Sudanese population. Two-hundred and fifty formalin-fixed paraffin-wax-embedded breast tissue blocks were used in this study. Of these, 200 were taken from breast cancer patients ascertained as study cases, and the remaining 50 were noninvolved surgical margin considered as normal breast tissue. Receptor expression was demonstrated using immunohistochemical techniques. The immune expression of ER beta was detected in 57.5% of breast cancers. It was differentially expressed in breast tissues encompassing normal, noninvasive, as well as invasive carcinoma (P=.02). There was no evidence of a significant relationship between ER beta and ER alpha expression. Among the ER alpha-negative tumor, 60.4% expressed ER beta. The expression of ER beta among this subgroup was significantly associated with good clinicopathological parameters such as negative Her2/neu, lower grade, and negative lymph node metastasis (P=.002). This study concludes that ER beta was commonly expressed among Sudanese patients with breast cancer, either co-expressed with ER alpha or expressed alone. In the ER alpha-negative subgroup, it was associated with better tumor outcomes suggesting ER beta should be included in the diagnostic protocol as an independent marker for favorable prognosis.