[Correlations between estrogen receptor and prognostic factors of patients with breast cancer. The Kanto Cooperative Study Group of Adjuvant Chemoendocrine Therapy for Breast Cancer, Japan].

We investigated possible correlations between estrogen receptor (ER) and prognostic factors in 3,789 patients with stage II or stage IIIa breast cancer in Japan. The patients with ER-positive tumors showed a significantly better prognosis in the 5-year survival rate and the 5-year disease-free survival rate compared with the patients with ER-negative-tumor. Positivities increased with increasing patient age, with increasing tumor size, and lowering degree of cell differentiation, and no relation was observed between the positivities and tumor sites, obesity index, and lymph-node metastasis.