Simultaneous micro measurement of steroid receptors in breast cancer

Quality Assurance for Steroid Receptor Assay in Human Breast Cancer: Six Years Experience of the Italian Committee

Since 1979 the quality control design proposed by the Italian ad hoc Committee has evaluated several lyophilized preparations with scalar receptor content; this permits the identification by linear regression analysis of systematic and non systematic errors. At present 41 laboratories from most of the national regions have joined the Italian Committee. The overall results of five years application of quality assurance in Italy show that there was a different pattern of imprecision with satisfactory indexes for intralaboratory performances but major variations in interlaboratory controls. There was also a remarkable difference of variability indices between the so-called "expert" and "new" laboratories; this problem can be reduced with practical seminars for new centers. On the basis of the results and experience achieved the Committee is starting another program of quality assurance for different new methodologies to provide guidelines for international working reference standards.

Prognostic Value of S-Phase Fraction in 920 Breast Cancer Patients: Focus on T1N0 Status

The aim of this study was to reexamine the prognostic role of tumor cell kinetics measured by S-phase fraction (SPF) and to establish its clinically relevant threshold values. SPF was determined by flow cytometry in a group of 920 consecutive breast cancer patients, all followed at our institute for 10 years (1988 to 1998). Mean age was 60.5 years (27–89 years). Median follow-up was 63 months (3–150 months). All patients had initial surgical treatment. SPF quartiles were: Q1=3.08%, median value = 5.98%, Q3=10.22%. A significant difference in overall specific survival was obtained between two populations divided by a cutoff at Q1 (p<0.0001). A multifactorial analysis including SPF and known prognostic factors such as tumor size, node status, histological grade, ER and PR status was performed using the Cox model in a population of 719 patients: univariate analysis showed that each of these factors had significant influence on overall survival. Multivariate analysis selected three of them, ranked by decreasing order of hazard ratio (HR) value: SPF (HR: 3.88, p<0.001), tumor size (HR: 2.49, p<0.001) and nodal status (HR: 2.28, p<0.001). In addition, when tumors were stratified according to SPF quartile values, there were statistically different overall survival curves in patients with small tumors (<2 cm) and in axillary node-negative patients.

Prognostic factors in 1,038 women with metastatic breast cancer

BACKGROUND

Treatment of metastatic breast cancer (MBC) remains palliative. Patients with MBC represent a heterogeneous group whose prognosis and outcome may be dependent on host factors. The purpose of the present study was dual: first, to draw up a list of factors easily available in everyday clinical practice requiring no sophisticated or costly methods and second, to provide results from a large cohort of women who underwent diagnostic and treatment at a single institution.

PATIENTS AND METHODS

From 1975 to 2005, a total of 1,038 women with MBC during their follow-up were included in this retrospective analysis. Patients were subsequently assigned to five groups according to the period of metastatic diagnosis.

RESULTS

It is shown that age at initial diagnosis, hormonal receptor status and site of metastasis are the most relevant prognostic factors for predicting survival from the time of metastastic occurrence. It is also shown that a metastasis-free interval is an easily and immediately available multifactorial prognostic index reflecting the multiparametric variability of the disease.

CONCLUSION

These fundamental observations may assist physicians in evaluating the survival potential of patients and in directing them toward the appropriate therapeutic decision.

Epidermal growth factor receptor expression in 780 breast cancer patients: a reappraisal of the prognostic value based on an eight-year median follow-up

PURPOSE

Because new therapeutic approaches target tumors expressing epidermal growth factor receptor (EGFR), the aim was to undertake a thorough analysis of the expression profile of EGFR in breast cancer and to reassess its prognostic value.

PATIENTS AND METHODS

Tumor EGFR levels were determined by a specific ligand binding assay in 780 consecutive breast cancer patients followed in our institute between 1980 and 1993. Mean age was 61 years (25-85 years). All patients had undergone tumor resection with axillary lymph node dissection: 373 patients (47.8%) underwent mastectomy, 37 (5%) subcutaneous mastectomy and 370 (47.2%) tumorectomy.

RESULTS

EGFR levels ranged between non-detectable up to 789 fmol/mg protein. EGFR median value was 9 fmol/mg protein and only a small proportion of patients exhibited a relatively marked EGFR expression. There was no link between tumor size, grade, node status and EGFR tumoral levels. There was a constant and significant decrease in EGFR tumoral levels according to patient age. A significant inverse relationship was found between estradiol receptors (ER) and EGFR. Median follow-up was 97 months with a minimum at 4 months and a maximum at 228 months. From univariate analysis it was found that histological grade, tumor size, node status and ER status were all significant predictors of survival, considering metastasis-free as well as overall survival. Using multivariable analysis, only histological grade, tumor size and node status remained independent predictors of survival.

CONCLUSION

EGFR determination is of limited value as a prognostic indicator in breast cancer.

Epidermal growth factor receptor assay: validation of a single point method and application to breast cancer

Epidermal growth factor (EGF) is a 6000 kDa peptide which exerts its biological effects by binding to a specific cell membrane receptor (EGF-R). Extensive studies on EGF-R in breast tumors have demonstrated the prognostic value of such assays. EGF-R measurement is also reportedly potentially useful in other tumors. Classically, the EGF-R content of tumor cell membrane preparations is evaluated by competition between a given concentration of labeled ligand and various concentrations of unlabeled ligand. The large quantity of tumor tissue required (approx. 0.5 g) is a serious limitation for wide-spread use of EGF-R assays. In order to validate a miniaturized EGF-R assay method, the principle of a single-dose technique (SD) using a single concentration of labeled ligand (1 nM) was investigated in the present work. Only 100-150 mg wet tissue were required for routine analysis by the SD method. The correlation between the SD method and Scatchard analysis calculated from 41 different breast carcinoma samples was very satisfactory (r = 0.973, p less than 0.001). Analysis of intra-assay and inter-assay reproducibility revealed a comparable EGF-R status in given samples. The correlation between EGF-R levels and steroid receptors was investigated in 105 individual breast tumors. EGF-R levels were inversely correlated with the estradiol receptor values. No correlation was found with progesterone receptors. The simplified SD method for EGF-R measurement appears suitable for large scale clinical studies aimed at investigating the potential utility of this biological tumor marker.

Oestrogen and progesterone receptor status in bone biopsy specimens from patients with breast cancer

Of 16 breast cancer patients with histologically proven, tumour-infiltrating biopsy specimens most had low ER and PR values; the ER and PR contents varied between 0 and 135 and 0 and 44 fmol/mg protein, respectively. With the conventional clinical threshold of 10 fmol/mg protein, 8 specimens (50%) were ER-PR-, 4 (25%) ER-PR+, 3 (19%) ER+PR+ and 1 (6%) ER+PR-. ER levels were significantly lower in the tumoral bone lesion compared with the primary tumour. For 15 patients with negative biopsies and without endocrine treatment, ER and PR concentrations were quantifiable (2 fmol/mg protein or more) in 9 (60%) and 11 cases (73%), respectively. 8 of 9 patients over 55 (89%) were ER+ (2 fmol/mg protein or more). Conversely, for patients under 55, 1 of 6 (17%) was ER+ (P less than 0.001). Results for PR were similar. These data strongly suggest that steroid receptors are present in healthy bone tissue.

Tamoxifen metabolism: pharmacokinetic and in vitro study

The qualitative and quantitative importance of tamoxifen (TMX) metabolism in vivo led us to investigate further the metabolic profile of this major anti-oestrogenic drug in a significant group of 81 breast cancer patients and to evaluate the respective in vitro activity of each metabolite. TMX and its four metabolites described until now (NDT, 4-OHT, Y, Z) were measured in blood (HPLC method) at the time of first drug intake and at the steady state. Between these two states, the unchanged drug relative proportion dropped from 65% to 27%. Demethylation was the major metabolic pathway. For 13 clinically evaluable patients, there was no significant difference in the distribution of serum levels of TMX and metabolites as a function of response to treatment. In vitro studies were performed on two human breast cancer cell lines: MCF-7, oestrogen receptor and progesterone receptor positive (ER+, PR+) and CAL-18 B (ER-, PR-). Cytostatic effects were evaluated by the tritiated thymidine incorporation test. TMX and all metabolites were active on these two cell lines, but the 50% inhibitory concentrations (IC50) were 4-250-fold higher in CAL-18 B than in MCF-7, depending on the metabolite considered. For the MCF-7 cells only, the antiproliferating activity was parallel to the relative binding affinity for ER. Moreover, for the MCF-7 cells only, the effects of these drugs were partially reversed by oestradiol (E2), the higher the metabolite affinity for ER, the lower the reversal efficacy. These compounds were tested in mixtures at proportions duplicating those found in patients after initial drug intake (mixture D1), and the steady state (mixture Css). The mixtures were also compared to the equimolar unchanged drug. No differences were seen among these three experimental conditions for either MCF-7 or CAL-18 B. A dose-effect relationship was noted. Overall, TMX and its metabolites exert a dual effect: when concentrations are below a threshold between 2 x 10(-6) and 10(-5) M, the drugs are mainly cytostatic; this effect is related to their affinity for ER. At higher relevant clinical concentrations, a cytotoxic activity is observed and it appears independent of the presence of ER.

High-performance liquid chromatography of steroid hormones

Although a considerable amount of work has been carried out in the last ten years in developing methods for the separation of steroids by HPLC, it is still not widespread for the reasons discussed above. There is however no doubt that further developments in HPLC technology, in increasing sensitivity and/or specificity of detection systems, perhaps with microbore columns, may lead to an increase in the use of this powerful analytical procedure as an additional separation method to improve specificity of assay. Solution of the problem of simple interfacing of HPLC systems with mass spectrometers (discussed in another chapter by Games) should further increase the application of HPLC. HPLC is of particular value in providing a means of separating unstable compounds prior to assay by relatively nonspecific quantitation methods. Most steroids do not fall into this category, but the steroid vitamin D and its metabolites do and HPLC has proved in this area to be invaluable (see chapter by Jones & DeLuca). There are a multiplicity of different HPLC systems for the separation of steroids, varying in column type (and manufacturer), solvent composition and method of elution, temperature of elution, etc., and only a few attempts have been made to rationalise these data. It would therefore seem that a fruitful area of future study would be the investigation of computerised systems for the selection and optimisation of HPLC systems for particular steroid separations.

HPLC micromethod for simultaneous measurement of estradiol, progesterone, androgen and glucocorticoid receptor levels. Application to breast cancer biopsies

Estradiol (ER), progesterone (PR), androgen (AR) and glucocorticoid receptor (GR) levels were assayed in 25 breast cancer tumors. The tissue was pulverized and homogenized in buffer, then divided into two parts: one was assayed by the standard dextran-coated charcoal method (DCC), with Scatchard plot analysis, the other was assayed by a micromethod developed in our laboratory, as described below: --incubation of the cytosol with several ligands (labelled and unlabelled) selected to avoid unwanted cross-reactions --DCC separation, followed by extraction of all receptor-bound steroids by precipitation of proteins with methanol/TCA --separation of these steroids on a high pressure liquid chromatography (HPLC) column using a methanol/water solvent --collection of the fractions of the column outlet and counting. Use of three labelled ligands and appropriate unlabelled ligands allowed assays of the four receptors. This micromethod was highly correlated with the standard method: ER = 0.985 (P less than 0.001); PR = 0.999 (P greater than 0.001); AR = 0.989 (P less than 0.001); GR = 0.867 (P less than 0.001). Thresholds of positivity were not modified. This micromethod allowed simultaneous measurement of several receptors in 40 mg biopsy specimens and can be applied to other hormone-dependent tissues.

Optimised analysis of tamoxifen and its main metabolites in the plasma and cytosol of mammary tumours

Recent biochemical and pharmacological findings concerning tamoxifen (TMX) have proven that both the unchanged drug and the main metabolites, N-desmethyltamoxifen (NDT) and 4-hydroxytamoxifen (4OHT) are biologically active. An HPLC method based on on-line post-column UV irradiation with fluorescence detection is described. Optimized conditions allowed complete and rapid separation of TMX 4OHT, NDT and two other recently reported metabolites, Y and Z. This method was applied to plasma and cytosol drug and metabolite analyses. In plasma, from the moment of initial drug administration until the steady state (after 1 month or more of continuous oral TMX treatment), the values of NDT to TMX ratios were completely reversed: 22 to 215 in mean %, P less than 0.01. The presence of metabolites Y and Z is significant. 4OHT, hardly detectable at the first dose, was measured at the steady state with high interpatient variability. It is hypothesized that metabolite evolution with time may be due to auto-induction of drug metabolism. In cytosols, which were all obtained during continuous TMX treatment, the ratios between TMX and metabolites were comparable to those observed in plasma, but with greater interpatient variability. Metabolite Y was not detectable in cytosols. This variability was not linked to the levels of cytosolic oestradiol receptors before initiation of treatment.

Estrogen and progestin receptor assay in fine needle aspirates of breast cancer: methodological aspects

A methodology, originally built up in our laboratory, for the simultaneous determination of estrogen (ER) and progesterone (PR) receptors on small samples of tumor tissues, has been adapted to fine needle aspirates (FNA) of breast tumors. The method is based on a simultaneous incubation of aliquots of high-salt (0.4 M KCl) cytosols with tritiated estrogen and progestin tags. The mixture of receptor-bound ligands is isolated by dextran-coated charcoal and extracted by ethanol. The extracted ligands are separated quantitatively by HPLC and counted by liquid scintillation. FNA provides sufficient cellular material for ER and/or PR assay by single point (5 nM) dextran-coated charcoal (DCC) assay. FNA samples, being contaminated by blood, [3H] R 2858 and [3H] O 2058 are appropriate tags for ER and PR respectively, giving lowest non-specific binding. Sixty-five simultaneous estrogen and progestin receptor determinations on FNA at time of diagnosis were compared to the individual assays performed on the surgical sample obtained from the same patients a few weeks after diagnosis. The correlation between the 2 sets of determinations is excellent in 60 cases with sufficient FNA cellularity. This correlation validates the reliability of estrogen and progestin receptor determination on FNA in the majority of clinical cases.