Estrogen receptor status and response to chemotherapy in advanced breast cancer: the Tufts-Shattuck-Pondville experience

Estrogen Receptors and Response to Chemotherapy in Advanced Breast Cancer

The relationship between receptor status and response to combination chemotherapy was retrospectively analyzed in 50 patients with advanced breast carcinoma, previously untreated with systemic therapy. Overall objective response rate to combination chemotherapy was similar in ER+ cases (14 of 33, 42 %) and in ER– (9 of 17, 53 %). The median duration of response was significantly longer in ER+ cases (48 weeks) than in ER– ones (26 weeks, P = 0.03). Response rate to cytotoxic chemotherapy does not appear to correlate with ER status.

Adjuvant chemotherapy in oestrogen-receptor-poor breast cancer: patient-level meta-analysis of randomised trials

BACKGROUND

The long-term effects of adjuvant polychemotherapy regimens in oestrogen-receptor-poor (ER-poor) breast cancer, and the extent to which these effects are modified by age or tamoxifen use, can be assessed by an updated meta-analysis of individual patient data from randomised trials.

METHODS

Collaborative meta-analyses of individual patient data for about 6000 women with ER-poor breast cancer in 46 trials of polychemotherapy versus not (non-taxane-based polychemotherapy, typically about six cycles; trial start dates 1975-96, median 1984) and about 14 000 women with ER-poor breast cancer in 50 trials of tamoxifen versus not (some trials in the presence and some in the absence of polychemotherapy; trial start dates 1972-93, median 1982).

FINDINGS

In women with ER-poor breast cancer, polychemotherapy significantly reduced recurrence, breast cancer mortality, and death from any cause, in those younger than 50 years and those aged 50-69 years at entry into trials of polychemotherapy versus not. In those aged younger than 50 years (1907 women, 15% node-positive), the 10-year risks were: recurrence 33% versus 45% (ratio of 10-year risks 0.73, 2p<0.00001), breast cancer mortality 24% versus 32% (ratio 0.73, 2p=0.0002), and death from any cause 25% versus 33% (ratio 0.75, 2p=0.0003). In women aged 50-69 years (3965 women, 58% node-positive), the 10-year risks were: recurrence 42% versus 52% (ratio 0.82, 2p<0.00001), breast cancer mortality 36% versus 42% (ratio 0.86, 2p=0.0004), and death from any cause 39% versus 45% (ratio 0.87, 2p=0.0009). Few were aged 70 years or older. Tamoxifen had little effect on recurrence or death in women who were classified in these trials as having ER-poor disease, and did not significantly modify the effects of polychemotherapy.

INTERPRETATION

In women who had ER-poor breast cancer, and were either younger than 50 years or between 50 and 69 years, these older adjuvant polychemotherapy regimens were safe (ie, had little effect on mortality from causes other than breast cancer) and produced substantial and definite reductions in the 10-year risks of recurrence and death. Current and future chemotherapy regimens could well yield larger proportional reductions in breast cancer mortality.

Differential response to chemotherapy in metastatic breast cancer in relation to estrogen receptor level. Results of a prospective randomized study

The predictive value of estrogen receptor (ER) level for response to chemotherapy was studied in 182 patients with metastatic breast cancer in a prospective study. Patients were stratified according to ER status and dominant site of disease and randomized to one of three regimens: cyclophosphamide, 5-Fluorouracil, and prednisone (CFP) versus CFP, methotrexate, and vincristine (CFPMV) versus doxorubicin and cyclophosphamide (AC). There was no significant differences in all response categories (P = 0.21), was taken as a predictor for response to chemotherapy, there was no significant difference in overall response (P = 0.61) between ER+ (62/108, 57%) and ER- patients (31/49, 63%). However, there was a significant trend toward a higher degree of response in ER- patients (more complete response [CR] nine of 49, 18%, and fewer failures six of 49, 12%) than in ER+ (less CR seven of 108, 7%, and more failures 37/108, 34%) (P = 0.006). Patients with higher measured levels of ER showed worse response (Kendall's tau C, P = 0.026). This trend for ER- patients to have better response than ER+ patients was generally consistent, regardless of the predominant site of metastases or chemotherapy regimen (P = 0.04 for CFP; P = 0.08 for CFPMV; and P = 0.20 for AC). The advantage of a better response for ER- patients was nullified by an earlier relapse which was reflected in longer duration of remission, time to treatment failure, and survival in favor of ER+ patients (12.3 months versus 7.3 months remission duration, 18.7 months versus 13.6 months survival in partial responders). These data suggest that ER- patients respond to a higher extent to chemotherapy but relapse sooner than ER+ patients, suggesting a more rapid growth for ER- tumors. In patients with ER- tumors and poorer prognosis on conventional chemotherapy, new trials of intensive consolidation after response should be considered.

Relationship of quantitative estrogen-receptor level and clinical response to cytotoxic chemotherapy in advanced breast cancer. An extramural analysis

Three hundred twenty-four patients with advanced breast cancer from seven institutions whose x-rays and records had been externally reviewed for evidence of objective regression of disease were again reviewed, this time regarding their responses to chemotherapy in relationship to estrogen receptor (ER) levels. Higher levels of ER were found in older or postmenopausal women, in those with longer disease-free intervals or with osseous metastasis, and in women whose chemotherapy treatment was given later relative to first recurrence of disease. Response to chemotherapy in 60%, or 194 cases, was comparable to the response rate in other patients treated with the same drugs. Patients with ER levels greater than 3 fmoles/mg cytosol protein had a response rate of 67% and 58% of patients with ER less than 3 fmoles responded. Regimens containing Adriamycin (doxorubicin) and Cytoxan (cyclophosphamide) in combination appeared to give higher response rates. Addition of vincristine or prednisone did not improve response rates. The best response rate (88%) was in 16 patients who had ER levels in excess of 50 fmoles and received four or more drugs. There appeared to be a benefit from increased number of drugs and from quantitatively high ER levels. There is a discussion of the possible implication of these findings.

Breast cancers: estrogen and progesterone receptor status as a predictor of in vitro chemotherapeutic response

Although clinical observations have shown that estrogen receptor-positive (ER+) breast tumors are more responsive to hormonal therapy than ER-negative (ER-) tumors, it remains controversial whether ER status can predict chemotherapeutic response. To determine if there was any correlation between estrogen and progesterone values and in vitro chemosensitivity to various anticancer drugs, clonogenic (CA), estrogen (ERA), and progesterone (PRA) assays on breast cancers were performed on 100 patients. Clonogenic assays were performed using the double-layer soft agar technique with continuous drug exposures. ERAs and PRAs were performed using the charcoal-coated dextran method. Chemosensitivity was defined as 50% inhibition of colony formation. ERA was considered positive if greater than or equal to 5 fmole/mg cytosol and PRA positive if greater than or equal to 10 fmole/mg cytosol. Significant tumor growth (greater than 30 colonies/plate) was achieved in 81/100 assays. ERA and PRA values were not predictive of colony formation in vitro. Of all agents or combinations of agents tested (L-PAM, 5-FU, MTX, adriamycin, vinblastine, cis-plat, FAC, CMF), only the response to 5-FU correlated significantly with ERA. Eight of 11 (73%) of the ER- tumors were sensitive to 5-FU, whereas only 6/20 (30%) of ER+ tumors were sensitive (P less than 0.05). ER- tumors were also more likely to be sensitive to CMF (P = 0.09) and adriamycin (P = 0.07) than ER+ tumors. PRA values were not predictive of chemosensitivity, nor did combining PRA and ERA enhance the predictive value of ERA alone.

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.