A simple method for the determination of oestrogen receptor concentrations in breast tumours and other tissues

Summary.-The relationship between oestrogen-receptor protein (ER) content of the tumour and the response to endocrine therapy was determined in 119 patients, in a collaborative prospective study. Twenty-eight of the 80 patients with measurable ER responded to treatment according to UICC criteria, compared with only 3/39 without ER. It was found that site of biopsy did not influence the result, but tumour content of the tissue sample was significantly related to the presence of receptors. The organizational problems of such a study are discussed.RESULTS from a number of centres in the United States and Europe indicate that the response of advanced breast cancer to endocrine therapy can be correlated with the oestrogen-receptor content of the tumour (McGuire et al., 1975). In 1974 the British Breast Group initiated a study to investigate these reports in a prospective series.Two centres took part in our study, both referring all patients suitable for endocrine therapy over a 30-month period (1.10.74-31.3.77). The clinicians were not informed of the results of oestrogen-receptor assays, and patients were treated according to the routine protocols for each centre. Our study included external clinical assessment of response to therapy, pathological review of all biopsy specimens, and a comparison of laboratory methodology. METHODSCriteria for inclusion.-Consecutive unselected patients from Guy's Hospital and the Royal Infirmary of Edinburgh breast clinics were included in this study, provided they had evidence of progressive, histologically confirmed, locally advanced or disseminated breast cancer, and had a lesion accessible for biopsy for the estimation of oestrogenreceptor content. Most patients had not received previous systemic therapy for advanced disease, but in the event of previous additive hormone therapy, at least 14 days were allowed to elapse before biopsy was performed. Biopsy, from a single site, was carried out immediately before new endocrine therapy was started.Pathological assessment.-Sections from every biopsy specimen were examined by one pathologist (R.R.M.) without knowledge of the oestrogen-receptor assay result, to determine whether adequate tumour tissue was present. An 8-point scoring system was devised as follows:(a) the overall proportion of neoplastic tissue to normal tissue in the section was allocated a score of 1 (<50 /) to 4 (100%) (b) the proportion of malignant epithelial cells to stroma within the neoplasm was scored 1 (<50%) to 4 (100%).

Section: Methodsmentioning

confidence: 99%

Oestrogen receptors and the response to endocrine therapy in advanced breast cancer

Roberts¹,

Rubens²,

King³

et al. 1978

“…Oe8trogen-receptor activity was determined by the method of Hawkins, Hill and Freedman (1975). A portion (160 >mg) of fat-free tumour was homogenized in tris buffer (0-25 M sucrose, 10 mM tris and 1 mM ethylene diamine tetra-acetate) at the rate of 100 mg/ml for 3 x 15 s, with intervals for cooling between periods of homogenization.…”

Section: Methodsmentioning

confidence: 99%

“…Each tumour wTas excised from the breast, measured and sectioned into 2-3 cubes. Each cube was divided into 2, one portion being used for histological examination, the other for oestrogen-receptor assay.Oe8trogen-receptor activity was determined by the method of Hawkins, Hill and Freedman (1975). A portion (160 >mg) of fat-free tumour was homogenized in tris buffer (0-25 M sucrose, 10 mM tris and 1 mM ethylene diamine tetra-acetate) at the rate of 100 mg/ml for 3 x 15 s, with intervals for cooling between periods of homogenization.…”

mentioning

confidence: 99%

Reproducibility of measurements of oestrogen-receptor concentration in breast cancer

Hawkins¹,

Hill²,

Freedman³

et al. 1977

Summary.-The reproducibility of measurements of oestrogen-receptor activity has been examined in multiple specimens from a rabbit uterus, a rat mammary tumour and human breast tumours. The relationship between receptor concentration and tumour histology has also been investigated in 11 large primary tumours.In the animal tissues, receptor measurements were relatively reproducible (co- In the 11 primary breast cancers selected for study, the level of receptor activity was related to menopausal status and the tumour content of the specimen.We conclude that the receptor activity detected varies within a tumour and depends upon the tumour content of the biopsy specimen. Predictions based on precise quantitation of receptor concentrations may therefore necessitate replicate tumour sampling and correction for the fraction of non-tumour tissue in each sample.CURRENTLY, the best index of the hormonal sensitivity of a breast cancer is the concentration of oestrogen-receptor protein in the cytoplasm of the tumour. (Folca, Glascock and Irvine 1961;Jensen et al., 1971;McGuire et al., 1975). We have, therefore, investigated the reproducibility of receptor measurements and the role of morphological factors in determiining variations in receptor concentration. MATERIALS AND METHODSTissues.-To examine the precision of the receptor assay, multiple (4-8) portions were cut at 0-40C, from each of 4 tissues selected for their apparent homogeneity. These tissues 'were the uterus from a non-pregnant rabbit, a rat mammary carcinoma (generated by the intragastric administration of 30 mg dimethylbenz(a)anthracene at 50 days of age) a large, cellular, intracanalicular fibroadenoma removed surgically from a 59-year-old woman, and a lymplh node which had been largely replaced by anaplastic breast carcinoma from a 75-year-old woman. Each portion of tissue was assayed for oestrogen-receptor activity.To examine the reproducibility of receptor measurements in human breast cancer an(d relate this to morphology, 11 mastectomy specimens containing large, primary breast cancers were collected on ice. Each tumour wTas excised from the breast, measured and sectioned into 2-3 cubes. Each cube was divided into 2, one portion being used for histological examination, the other for oestrogen-receptor assay.Oe8trogen-receptor activity was determined by the method of Hawkins, Hill and Freedman (1975). A portion (160 >mg) of fat-free tumour was homogenized in tris buffer (0-25 M sucrose, 10 mM tris and 1 mM ethylene diamine tetra-acetate) at the rate of 100 mg/ml for 3 x 15 s, with intervals for cooling between periods of homogenization.

“…The potential sources of laboratory variability have been well reviewed by Thorpe (1987). Intralaboratory variation in a number of studies using LBA is reported to range from 15% to 34% (Hawkins et al, 1975(Hawkins et al, , 1987bTaylor et al, 1982; Davis et al, 1984;Bojar, 1986;Anderson et al, 1989 Nicholson et al, 1986) and 3.7% to 16.7% (Bojar, 1986;Jordan et al, 1986;Leclerq et al, 1986;Nicholson et al, 1986) respectively. The interlaboratory CV for EIA was reported to range between 10% and 19% (Bojar, 1986;Leclerq et al, 1986).…”

mentioning

confidence: 99%

Oestrogen receptor: a stable phenotype in breast cancer

Robertson

1996

127

Summary Oestrogen receptor (ER) expression in breast cancer is regarded as a phenotype that may change during the natural history of the disease or during endocrine therapy. It has been suggested that in up to 70% of tumours that show acquired resistance the mechanism may be changed in ER status from positive to negative. This paper proposes an alternative hypothesis that ER expression is a stable phenotype in breast cancer. The paper reviews the literature on ER expression during the natural history of breast cancer in patients and also presents data on the effect of endocrine therapy on ER expression. If the alternative hypothesis is true it has important implications for treatment from chemoprevention to acquired endocrine resistance in advanced disease. Equally, if the hypothesis is true, attempts to develop laboratory models of endocrine resistance where ER-positive tumours become ER negative need to be re-evaluated.Keywords: breast cancer; oestrogen receptor; stable phenotypeThe oestrogen receptor (ER) is a 65 kDa oestrogen-binding protein expressed by 46-77% of breast cancers (Walt et al., 1976;Knight et al., 1977; Maynard et al., 1978;Brooks et al., 1980;Osborne et al., 1980; Croton et al., 1981;Howell et al., 1984;Hawkins et al.,1987a;Williams et al., 1987;Clarke and McGuire, 1988). It is a generally held view that ER expression is not a permanent phenotype in breast cancer cells Moolgavakar et al., 1980; Encarnacion et al., 1993; Morrow and Jordon, 1993;Nomura et al., 1985;Jordan, 1994;Paik et al., 1994). One reason for this view is the belief that patients with ER-positive primary breast tumours often develop ER-negative metastases in regional lymph nodes or distant sites. This has been interpreted to show that ER negativity correlates with more aggressive tumour biology and loss of cellular control. A second reason is the strong correlation between ER and therapeutic response to primary endocrine therapy (Samaan et al., 1981;Howell et al., 1984;Williams et al., 1987), which formed the basis for early hypotheses of endocrine sensitivity and resistance. Up to 60% of ER-positive tumours respond to hormone therapy (e.g. Tamoxifen), while for ER-negative tumours the figure is around 10% Samaan et al., 1981;Williams et al., 1987). Therapeutic response to endocrine therapy is not permanent and eventually all such tumours progress. As ER negativity is strongly associated with primary resistance to endocrine therapy it is generally accepted that when responding tumours subsequently progress that in the majority of tumours this is due to loss of ER expression by the tumour Moolgavakar et al., 1980;Nomura et al., 1985; Encarnacion et al., 1993;Morrow and Jordan, 1993;Jordan, 1994;Paik et al., 1994). This paper proposes the alternative hypothesis that ER is a stable phenotype in breast cancer cells.The discovery of monoclonal antibodies (Kohler and Milstein, 1975) subsequently led to specific antibodies being raised to ER (Green and Jensen, 1982 . The ER-ICA allowed assessment of tumour tissue sections (King ...