Relation of estrogen and/or progesterone receptor content of breast cancer to patient outcome following adjuvant chemotherapy.

In 1977 the National Surgical Adjuvant Breast and Bowel Project (NSABP) initiated a prospectively randomized clinical trial to evaluate the relative merits of 1-phenylalanine mustard and 5-fluorouracil (PF) with and without tamoxifen (T) as adjuvant therapy for patients with primary breast cancer and positive axillary nodes. A previous presentation of findings noted that there was a strong relationship between the outcome of those receiving PFT and the estrogen receptor (ER) and progesterone receptor (PR) content of their tumors. This report relates the outcome of the PF-treated patients in that trial with these tumor receptors. It indicates that the results observed following nonhormonal therapy (PF) are also related to tumor receptors. Both the disease-free survival (DFS) and survival (S) of women following PF therapy were influenced by the ER and PR content of their tumors. Subsequent to adjustment for other prognostic variables, the predictive influence of tumor ER persisted. Both the DFS (p = 0.0003) and the S (p = 0.00003) were significantly higher in those with greater than or equal to 10 fmol tumor ER than in those with less than 10 fmol ER. The PR significantly added to the predictive value of ER. Thus, this analysis is the first to demonstrate that having information on both ER and PR is important for predicting outcome of patients receiving adjuvant chemotherapy. The study does not provide information which correlates receptor status with the response of patients to adjuvant chemotherapy since there is no similar nonchemotherapy-treated group of patients in the trial. The findings continue to emphasize that there is a heterogeneity in outcome of breast cancer patients to adjuvant chemotherapy which is related to an increasing number of host and tumor variables. For proper assessment of overall results, it is essential that analyses employ tests for interaction to indicate homogeneity or heterogeneity of patient subsets and that adjustments be made for imbalances in tumor ER and PR as well as in other prognostic factors.

RCT Entities:   Population Interventions Outcomes