The Relationship of Estrogen Receptor, Endogenous Estradiol and Epidermal Growth Factor Receptor to the Proliferative Activity of Breast Cancer

In order to evaluate the relationship of the expression of estrogen receptor （ER）, endogenous estradiol （E2） and epidermal growth factor receptor （EGFR） to the proliferative activity of primary breast cancers, immunohistochemical studies were performed on 71 cases of primary breast cancer. Proliferative activity was evaluated by using anti-DNA polymerase α monoclonal antibody, CL22-2-42B, which reacts with cells in the proliferation cycle. The percentage of positive stained cancer cells was calculated and used as an indicator of the proliferative activity of each specimen. The relation of ER, endogenous E2 and EGFR to the proliferative activity was investigated. The results are summarized as follows: 1. The ER positive breast cancers had a lower proliferative activity than the ER negative breast cancers. 2. Among the ER positive breast cancers, E2 positive cancers had higher proliferative activity than E2 negative cancers. Thus endogenous E2 seems to play a role in the proliferation of ER positive breast cancers. 3. EGFR positive cancers had higher proliferative activity than EGFR negative cancers. 4. ER（-） EGFR（+） tumors had greater proliferative activity than ER （+） EGFR （-） tumors. The expression of EGFR relates much more closely to higher proliferative activity of breast cancer than ER.departmental bulletin pape