Histochemical estrogen binding An independent predictor of recurrence and survival in stage II breast cancer

Cox's proportional hazards regression model was used to analyze the prognostic significance of multiple variables affecting recurrence and survival in patients with Stage II breast cancer. Among the variables were biochemical estrogen (ER) and progesterone receptor (PgR) values and results of a histochemical estrogen‐binding assay using a fluoresceinated bovine serum albumin—estradiol conjugate where carrier and label were bound at position 17. In 190 cases ER and PgR were not found to be significantly associated with either disease recurrence or patient survival. On the other hand, patients with tumors that were demonstrably “rich” in estradiol ligand conjugate binding by histochemistry experienced both a longer disease‐free interval (P < 0.03) and survival (P < 0.02) than did patients whose tumors were “poor” in conjugate binding or showed a heterogenous population of positively and negatively stained cells. A patient with a tumor rich in estrogen binding was five times more likely to survive than a patient with a neoplasm that was poor in estrogen binding by histochemistry. These results indicate that the histochemical technique used provides new and independent parameters for determination of prognosis in Stage II breast cancer.