Although the role of the estrogen receptor α (ERα, previously called the estrogen receptor) in breast cancer is well established, that of the second human estrogen receptor (ER), estrogen receptorβ (ERβ), remains uncertain, The expression of cyclooxygenase II (COX II) could also be regulated by sex steroids such as estrogen and progesterone. To investigate whether the expressions of the ERβ, ERα, and COX II are elevated in more aggressive breast cancers, the expression of the ERβ was studied by immunohistochemical staining in 20 primary breast cancer and original breast cancer tissues from 20 recurrent cancer patients, and its associations with ERα and cyclooxygenase (COX) II were evaluated.

Paraffin tissue sections from 40 breast cancers. surgically excised at the Department of Surgery, the Catholic University of Korea. were obtained. The immunohistochemical analysis was conducted on 20 non-recurrent, and 20 recurrent primary breast cancer tissues, using polyclonal antibodies to ERβ, ERα, and the corresponding monoclonal antibodies to COX II.

Of the 40 patients, 15 (37.5%) were ERβ-positive. 30 (75%) were ERα-positive, and 24 (60%) were COX II-positive, The ERβ status was not related to the tumor size or menopausal status, but was related to the nodal status, The stati of ERα and COX II were not related to other clinico-pathological factors, The ERβ positivity was significantly more frequent in the study than the control group. (ERβ, p = 0.0222; ERα p = 0.1441; COX II, P = 100) The presence of ERβ was significantly related to the expression of ERα and COX II (p = 0.0455, P = 0.0381, respectively).

These results suggest that the expression of ERβ is associated with early recurrence in breast cancer and the expression of COX II in the presence of ERβ implies the possibility of prognostic significance.