Relative Importance of Estrogenand ProgesteroneReceptorAssays as PrognosticIndicatorsin PrimaryBreast Cancer: a Short-Term Study

This short-term study of the relative importance of estrogen and progesterone receptors shows that progesterone recep-tor correlates better than estrogen receptor with tumor recur-rence regardless of lymph-node status. Ufe-table analysis has effectively identified only two groups of patients that may be classified by progesterone receptor status alone. Proges-terone-receptor negativity correlated well with tumors of histological Grade Ill; estrogen-receptor positivity correlated with Grade I and II tumors. The earlier recurrence of Grade Ill breast tumors may explain why progesterone receptor is a better prognostic indicator than estrogen receptor in short-term studies. Measurements of estrogen receptors (ER) and progester-one receptors (PR) in primary breast cytosols are widely used as indicators of responsiveness to subsequent endocrine therapy (1). This is particularly true for PR after tamoxifen “priming ” of the tumor (2). Lymph-node status and the histological grade of the primary tumor (3) are established as good predictors of disease-free interval, but the role of ER and PR in predicting the likelthood of recurrence is more controversial. Factors such as the cutoff value used to distinguish between positive and negative results (4), the length of follow-up (5), and subsequent therapy after pri-mary mastectomy (6) have all been shown to influence the performance of ER and PR as predictors of recurrence or non-recurrence. Here we report our investigation of the relative impor-tance of ER and PR as predictors of disease-free interval (i.e., non-recurrence) in 179 patients with primary cancer of the breast during three years of follow-up