Prognostic significance of oestrogen and progestogen receptor activities in breast cancer

Novel oral selective estrogen receptor degraders (SERDs) to target hormone receptor positive breast cancer: elacestrant as the poster-child

INTRODUCTION

Estrogen receptor positive (ER+) breast cancer is the most common breast cancer subtype, and therapeutic management relies primarily on inhibiting ER signaling. In the metastatic setting, ER signaling is typically targeted by selective estrogen receptor degraders (SERDs) or aromatase inhibitors (AIs), the latter of which prevent estrogen production. Activating ESR1 mutations are among the most common emergent breast cancer mutations and confer resistance to AIs.

AREAS COVERED

Until 2023, fulvestrant was the only approved SERD; fulvestrant is administered intramuscularly, and in some cases may also have limited efficacy in the setting of certain ESR1 mutations. In 2023, the first oral SERD, elacestrant, was approved for use in ESR1-mutated, ER+/HER2- advanced breast cancer and represents a new class of therapeutic options. While the initial approval was as monotherapy, ongoing studies are evaluating elacestrant (as well as other oral SERDs) in combination with other therapies including CDK4/6 inhibitors and PI3K inhibitors, which parallels the current combination uses of fulvestrant.

EXPERT OPINION

Elacestrant's recent approval sheds light on the use of biomarkers such as ESR1 to gauge a tumor's endocrine sensitivity. Ongoing therapeutic and correlative biomarker studies will offer new insight and expanding treatment options for patients with advanced breast cancer.

A Comparative Review of Pregnancy and Cancer and Their Association with Endoplasmic Reticulum Aminopeptidase 1 and 2

The fundamental basis of pregnancy and cancer is to determine the fate of the survival or the death of humanity. However, the development of fetuses and tumors share many similarities and differences, making them two sides of the same coin. This review presents an overview of the similarities and differences between pregnancy and cancer. In addition, we will also discuss the critical roles that Endoplasmic Reticulum Aminopeptidase (ERAP) 1 and 2 may play in the immune system, cell migration, and angiogenesis, all of which are essential for fetal and tumor development. Even though the comprehensive understanding of ERAP2 lags that of ERAP1 due to the lack of an animal model, recent studies have shown that both enzymes are associated with an increased risk of several diseases, including pregnancy disorder pre-eclampsia (PE), recurrent miscarriages, and cancer. The exact mechanisms in both pregnancy and cancer need to be elucidated. Therefore, a deeper understanding of ERAP's role in diseases can make it a potential therapeutic target for pregnancy complications and cancer and offer greater insight into its impact on the immune system.

Oestrogen and Progesterone Receptors as Prognostic Variables in Hormonally Treated Breast Cancer

This study directly compares ER status and PgR status of primary tumour tissue measured by enzyme immunoassays for prediction of response to therapy and survival in 99 women with breast cancer treated by hormone therapy. ER and PgR status alone both correlated with response to therapy (p=0.002 and p=0.02 respectively), time to progression (p<0.0001 and p=0.003 respectively) and survival (p<0.001 and p=0.01 respectively). 67% of tumours ER(+)/PgR(+) showed responsive or static disease compared to 25% of tumours ER(-)/PgR(-). Tumours of mixed phenotype (i.e. ER(+)/PgR(-) and ER(-)/PgR(+)) showed an intermediate response rate of 46%. Similar findings were observed when tumour phenotype was compared with overall survival. Combining ER and PgR allows more accurate prediction of clinical outcome but does not aid in selecting individual patients for endocrine therapy.

Progesterone Receptor (PGR) Gene Variants Associated with Breast Cancer and Associated Features: a Case-Control Study

Insofar as altered estrogen receptor-progesterone receptor (PR) expression contribute to breast cancer pathogenesis, previous studies examined the association of genetic variation in PR gene (PGR) with breast cancer, but with mixed outcome. We evaluated the association between PGR variants, and breast cancer and associated features. A retrospective case-control study involving 183 female breast cancer patients, and 222 control women. PGR genotyping was done by real-time PCR. Minor allele frequencies of rs1042838, rs590688, and rs10895068 PGR gene polymorphisms were significantly higher in breast cancer patients compared to controls. Patients carrying rs1042838 G/T, rs590688 C/C, and rs10895068 G/A genotypes had higher risk of breast cancer, while carriage of rs3740753 G/G genotype was associated with marginal reduction in breast cancer risk. In addition, carriage of rs1042839, rs3740753, and rs10895068 minor allele was associated with Her2 status, while rs3740753 and rs10895068 were associated with effective hormone replacement therapy. Furthermore, carriage of rs10895068 minor allele in breast cancer women were also associated with age at first pregnancy, hormone receptor (RH) status, and previous use of oral contraceptives. PGR haploview analysis documented moderate-strong linkage disequilibrium (non-random association of alleles at different loci) between 7 of the 8 tested PGR SNPs, thus allowing construction of 7-locus PGR haplotypes. Two haplotypes, ATGCCGA and GTGCCGA, both containing rs590688, were positively associated with breast cancer, thus assigning a breast cancer-susceptible nature to these haplotypes. PGR rs1042838, rs590688, and rs10895068, and ATGCCGA and GTGCCGA haplotypes are related with increased breast cancer susceptibility in Tunisian women.

Prognostic Significance of Single Progesterone Receptor Positivity: A Comparison Study of Estrogen Receptor Negative/Progesterone Receptor Positive/Her2 Negative Primary Breast Cancer With Triple Negative Breast Cancer

Single progesterone receptor positive (PgR+), especially in form of ER-/PgR+/HER2-, is a nonnegligible phenomenon. Little is known about the characteristics and the role of single PgR positive in this phenotype. Therefore, we explore the significance of single PgR positivity by comparing ER-/PgR+/HER2- breast cancers with triple negative breast cancers (TNBCs).Three thousand nine hundred sixty-six cases of primary invasive breast carcinoma operated consecutively from January 2005 to May 2008 in Cancer Hospital, Chinese Academy of Medical Sciences were examined. Two hundred forty (6%) cases were identified as ER-/PgR+/HER2- breast cancers and 348 (8.8%) cases as TNBCs. Clinicopathological characteristics and survivals were analyzed respectively and then compared between 2 subtypes.Compared with patients with TNBCs, ER-/PgR+/HER2- tumor tended to have lower tumor grade (Grade 3: 45.7% vs. 37.5%, P = 0.051) and smaller tumor size (P = 0.036). However, no differences were found between ER-/PgR+/HER2- and TNBC patients in relapse-free survival (RFS) and OS. The 5-year RFS rates were 80.7% and 77.4%, respectively (P = 0.330) and the 5-year OS rates were 88.0% and 85.2%, respectively (P = 0.290). ER-/PgR+/HER2- patients receiving adjuvant endocrine treatment had better RFS (P = 0.016) and overall survival (OS) (P < 0.0001) than patients receiving no endocrine therapy.This exclusive analysis of patients with ER-/PgR+/HER2- breast cancers showed that this subtype exhibited an aggressive behavior as TNBC, suggesting that it should also be regarded as biologically distinctive group and single PgR positive itself is not a good prognostic factor. However, adjuvant endocrine therapy could still benefit this group of patients. Further investigations should be done to elucidate the underlying mechanism.

Role of calcium sensing receptor (CaSR) in tumorigenesis

The extracellular Ca(2+)-sensing receptor (CaSR) is a robust promoter of differentiation in colonic epithelial cells and functions as a tumor suppressor in colon cancer. CaSR mediates its biologic effects through diverse mechanisms. Loss of CaSR expression activates a myriad of stem cell-like molecular features that drive and sustain the malignant and drug-resistant phenotypes of colon cancer. This CaSR-null phenotype, however, is not irreversible and induction of CaSR expression in CaSR-null cells promotes cell death mechanisms and restores drug sensitivity. The CaSR also functions as a tumor suppressor in breast cancer and promotes cellular sensitivity to cytotoxic drugs. BRCA1 and CaSR functions intersect in breast cancer cells, and CaSR activation can rescue breast cancer cells from the deleterious effect of BRCA1 mutations.

Adjuvant cyclic Tamoxifen and Megestrol acetate treatment in postmenopausal breast cancer patients – Longterm follow-up

AIMS

To evaluate possible differences in effect on recurrence-free survival (RFS) and overall survival (OS) in node positive postmenopausal breast cancer patients receiving Tamoxifen or cyclic Tam and Megestrol acetate as adjuvant treatment.

METHODS

Between 1989 and 1994, 489 patients with pT(1-2)pN+ hormone receptor positive or unknown tumours were included in a randomized national multicenter study to receive either Tam alone or cyclic Tam (8 weeks) and MA (8 weeks) for 2 years. Final follow-up was completed as of June 2002. Time from start of treatment to first recurrence and novel primary breast tumour, overall survival and cancer specific survival were estimated.

RESULTS

No differences in RFS, OS or cancer specific survival were observed between the two treatment groups.

CONCLUSIONS

Adjuvant treatment used as standard Tam alone, compared to Tam and MA, as employed in this group of patients gave similar outcomes. Side effects that led to cessation of study medication were observed in both arms.

Progesterone receptor expression is a marker for early stage breast cancer: implications for progesterone receptor as a therapeutic tool and target

We determined the association of estrogen receptor (ER) and progesterone receptor (PR) expression in invasive breast cancer with stage at diagnosis. Univariate analyses indicated that although ER and PR expression were inversely associated with grade (P<0.0001), only PR expression (P<0.01) was inversely associated with stage. Multivariate analyses, adjusted for covariates, including HER-2/neu expression, indicated that PR (odds ratio (OR), 0.88; confidence interval (CI), 0.77-0.99; P=0.03) and not ER expression (OR, 1.04; CI, 0.94-1.16; P=0.45) was inversely associated with stage. PR and not ER expression is a marker for early stage breast cancer.

Endocrine therapy for breast cancer: an overview

Endocrine therapy for breast cancer has been established in the adjuvant treatment for primary disease and in the treatment of advanced disease. The ER remains the best predictor of response although other factors exist and need to be identified. Pharmacological manipulation has been replacing ablative procedures. Tamoxifen used to be the most popular agent of choice and promising new agents include the pure anti-oestrogens and the third generation selective aromatase inhibitors. Ongoing and future studies will optimise treatment in established areas and will exploit its potential roles in preoperative use and chemoprevention.

The prognostic significance of the semiquantitatively determined estrogen receptor content of breast carcinomas. A clinicopathological study

Response of breast carcinomas to tamoxifen treatment depends, among others, on the estrogen receptor status. The estrogen receptor content was semiquantitatively determined in immunostained sections of stage 1 and 2 cancers of patients who had undergone tumor excision, tamoxifen treatment, adjuvant chemotherapy and radiotherapy. Weighted scores of the estrogen receptor content of the tumors were established by calculating the arithmetic means of the intensity of stained nuclei and the number of positively stained nuclei. Statistically, a cut-off value of > or = 2.1 signified a good prognosis; all patients whose tumors disclosed a weighted score of > or = 2.1 were alive and free of disease at the 10-year postoperative follow-up examination. On the other hand, one third of the patients whose carcinomas had a weighted score of < 2.1 presented with locally recurrent cancer, distant metastases, or both during the follow-up observation period. The statistically significant association between the patients' 10-year event-free survival and carcinomas with a weighted score of > or = 2.1 may serve oncologists in their decision making with respect to hormonal treatment.

Estrogen receptors and distinct patterns of breast cancer relapse

BACKGROUND

We conducted an analysis of prospectively collected data to compare the clinical behavior of ER-negative versus ER-positive tumors with respect to rates and sites of recurrence.

METHODS

A total of 647 patients with operable stage II or III breast cancer were enrolled in two consecutive adjuvant therapy protocols conducted between 1980 and 1986. The correlations between ER status and time to first recurrence, site of first recurrence, and time to breast cancer death were assessed on 558 (86%) patients with available ER status data using hazard function and hazard ratio function analysis.

RESULTS

The rates of recurrence were significantly higher in patients with ER-negative status for the first two years of follow-up, but not thereafter. Similar results were observed for breast cancer death, and these results held up after adjustment for differences in treatment, age, menopausal status, and tumor burden. When the site of first recurrence was studied, ER-negative status was associated with a significantly higher rate of tumor recurrence in the viscera and soft tissues, while ER-positive status was associated with significantly higher rates of tumor recurrence involving bone.

CONCLUSIONS

The clinical behavior of ER-positive tumors is different from ER-negative cancer. ER status had a pronounced effect on the rates and sites of recurrence. Furthermore, this apparent association diminished over the follow-up period. Recurrence rates were significantly higher in patients with ER-negative status for the first two years of follow-up, but not thereafter.

Outcome after extended follow-up in a prospective study of operable breast cancer: key factors and a prognostic index

In 1990, 215 patients with operable breast cancer were entered into a prospective study of the prognostic significance of five biochemical markers and 15 other factors (pathological/chronological/patient). After a median follow-up of 6.6 years, there were 77 recurrences and 77 deaths (59 breast cancer-related). By univariate analysis, patient outcome related significantly to 13 factors. By multivariate analysis, the most important of nine independent factors were: number of nodes involved, steroid receptors (for oestrogen or progestogen), age, clinical or pathological tumour size and grade. Receptors and grade exerted their influence only in the first 3 years. Progestogen receptors (immunohistochemical) and oestrogen receptors (biochemical) were of similar prognostic significance. The two receptors were correlated (r=+0.50, P=0.001) and displaced each other from the analytical model but some evidence for the additivity of their prognostic values was seen when their levels were discordant.

Selection of primary breast cancer patients for adjuvant endocrine therapy--is oestrogen receptor alone adequate?

Among 834 patients who had primary breast cancer treated by surgery without adjuvant systemic therapy, 363 had relapse treated by endocrine therapy alone. Patients with oestrogen receptor positive tumours (median: 70 vs. 45 months, p < 0.0001) or with non-progression at 6 months of therapy (median: 111 vs. 37 months, p < 0.0001) survived longer than those with oestrogen receptor negative tumours or with disease progression respectively, presumably due to the effect of therapy. On the other hand, the median disease-free interval, uninfluenced by therapy, showed a similar difference: oestrogen receptor positive versus negative = 29 versus 21 months, p < 0.005; non-progression versus progression = 40 versus 19 months, p < 0.0001. Patients with oestrogen receptor-positive tumours and non-progression at 6 months had the longest disease-free interval. The present study has established that there are factors, other than the oestrogen receptor, inherent in the primary tumour as reflected by the disease-free interval, which affect hormone sensitivity. Selection of adjuvant endocrine therapy based on the oestrogen receptor alone would deem inadequate. Further studies to elucidate other possible factors are warranted to refine the use of endocrine therapy, especially in the adjuvant setting when no indication of response is available.

Highly sensitive immunohistological study for detection of estrogen receptor in human breast cancer

BACKGROUND

Immunohistological methods for the detection of estrogen receptor in human breast cancer using formalin-fixed, paraffin-embedded tissue not only have the advantages of being cheaper and requiring less tissue but also have several theoretical advantages. For example, such methods enable direct histological visualization of the assessed tissue and thereby reduce sampling error. Traditional immunohistological methods (traditional LSAB), however, show false-negative reactions more often than the enzyme-binding immunoassay method (EIA).

METHODS

After determining 25 estrogen receptor-positive cases and 50 estrogen receptor-negative cases by EIA, we analyzed these same cases using a traditional LSAB method and a new highly sensitive immunohistological method for assaying formalin-fixed, paraffin-embedded tissue.

RESULTS

Using this new method, we detected 10 instances of positive estrogen receptors among the 50 EIA receptor-negative cases. The 25 EIA-positive cases were positive for estrogen receptor antigen except 1case using the new method.

CONCLUSIONS

This new method not only has the advantage of use in paraffin-embedded tissue but also is more sensitive than the EIA. We recommend this new method as a choice to decrease false-negatives.

Immunoradiometric measurement of pS2 in breast cancer--correlation with steroid receptors and plasminogen activators

pS2 was measured by radioimmunometric assay in tumour extracts from 197 breast cancer patients. Values ranged from 0 to 50 ng/mg protein (mean 9.6 and median 3 ng/mg). We found no correlation with age, menopausal status, nodal metastases, disease stage or tumour histology. There was, however, a linear relationship with both ER (p < 0.0001) (particularly nuclear ER) and PR (p < 0.0001) expression determined by enzyme immunoassay (ELISA), as well as a good correlation when high and low expressors were stratified on the basis of combined ER/PR expression using consensus cut-off points. Only 15% of ER - ve/PR - ve patients were classified as pS2 + ve compared with 83% of those who were ER + ve/PR + ve. pS2 was also directly correlated with high expression of tPA and inversely with uPA. Comparison with previous studies showed that the current ELISA method produced consistent results, in contrast to other methods, particularly those based on immunohistochemical detection. The close relationship between pS2 and both steroid receptors suggests that pS2 may be important in terms of defining hormone-responsive patients who are likely to benefit from endocrine therapy.

Prospective evaluation of prognostic factors in operable breast cancer

In 215 patients with operable breast cancer (T1-T3, N0-1, M0) and no other or previous cancer, presenting to a single breast unit, sufficient tumour was available for the prospective determination of four putative biochemical markers of prognosis: oestrogen receptor (ER) activity, cathepsin D (cath D), epidermal growth factor receptor (EGFR) activity and cyclic AMP-binding proteins (c-AMP-b). There were significant inter-relationships between ER and EGFR (r = -0.26), c-AMP-b and cath D (r = +0.32) and ER and c-AMP-b (r = +0.14). After follow-up (median 36.2 months), a total of 55 recurrences (18 locoregional only) and 35 deaths were recorded. By univariate analysis, up to 10 of 18 biochemical, clinical and histopathological variables of potential prognostic value were significantly related to disease-free interval or death, but by multivariate analysis only oestrogen receptor concentration and node status contributed significantly to risk of both distant recurrence/death; in addition, tumour size made a small contribution to the risk for a distant recurrence only. Only two parameters, tumour grade and ER concentration, were significantly related to risk of locoregional recurrence by univariate analysis, but by multivariate analysis, only tumour grade was important. It is concluded that tumour ER concentration, axillary nodal status and tumour grade remain as the most important prognostic factors in the early years after presentation of operable breast cancer, with a minor influence of tumour size. At this time, the prognostic significance of quantitative measurements of ER concentration, carefully controlled for the quality of both assay and tumour specimen, is probably greater than is generally appreciated. We have yet to identify other factors, which add significantly to the short-term prognostic value of these key features.

Oestrogen receptor: a stable phenotype in breast cancer

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 in 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.

Assessment of angiogenesis in breast carcinoma: an important factor in prognosis?

Recent evidence suggests that angiogenesis, as assessed by vascular density, may be an independent prognostic factor in breast carcinoma. The authors chose to examine this hypothesis further using two different methods, both using an immunohistochemical technique to assess vascularity. In the first, tissue sections from 93 patients with human breast carcinoma were immunostained for the endothelial antigen CD 34. Fields were selected at random in sections stained with the monoclonal antibody QBEnd/10, and both the number of blood vessels and percentage of endothelial cells per unit area measured using an interactive image analysis system (SEESCAN). In the second, an additional 72 patients were added and the 165 sections immunostained for CD31 (PECAM 1) using the monoclonal antibody JC 709. The area of highest vascular density was then identified and measured. A statistically significant correlation was found between percentage endothelial area and tumor type (P < .03) using the first method, and, for lymph node-negative patients only, between vascular density and tumor type (P < .02) using the second method. There was no correlation with lymph node status, recurrence, distant metastases, or overall survival using either method (minimum follow-up 12 years). The authors conclude that the evaluation of tumor angiogenesis using these methods does not provide additional prognostic information in this group of patients.

A new immunohistochemical antibody for the assessment of estrogen receptor status on routine formalin-fixed tissue samples

We describe a method for the immunocytochemical assessment of estrogen receptor (ER) status on routinely processed, formalin-fixed tissue using a recently developed commercially available monoclonal antibody (Dako 1D5) with a microwave antigen retrieval technique. A series of 90 cases of human breast carcinoma was analyzed and the staining was assessed using a semiquantitative microscopic scoring method and by assessment of the percentage of nuclei showing positive staining. The results were compared with assessment using another commercially available antibody (Abbott H222) and with clinical response to tamoxifen therapy. Direct comparison of the paired sets of H scores and the percentage of positively stained nuclei using the two different techniques showed a significant correlation. By assigning an arbitrary cut-off for positivity of H score = 50, assessment of ER status using DAKO 1D5 antibody was found to correlate with response to tamoxifen therapy with a sensitivity of 90% and a specificity of 51%, similar to values in previous studies using other methods. We conclude that assessment of ER status using this new antibody and technique gives accurate results on routinely processed, formalin-fixed tissue and may be used as an alternative to other methods.

Prognostic factors. Stage and receptor status in breast cancer

BACKGROUND

Anatomic and biologic indicators of prognosis provide the bases for management of patients with cancer of the breast. Combinations of these indicators are potentially more accurate than any alone. This review was undertaken to evaluate the prognostic relationship between stage and steroid hormone receptors.

METHODS

The literature was reviewed relative to the influences of tumor size, axillary metastases, and tumor estrogen receptors on the survival of patients with cancer of the breast.

RESULTS

Axillary node status is of primary importance as a predictor of recurrence and survival. Tumor size has only a secondary influence, but is prognostically useful in the absence of metastases. Estrogen and progesterone receptors provide prognostic information that is independent of axillary stage, but the influence is weak, often transient, and attributable at least partly to a close association with other biologic indicators of favorable prognosis.

CONCLUSIONS

Hormone receptors add to the prognostic information provided by anatomic stage, but the contribution is insufficient to support a decision for or against systemic adjuvant therapy.

Prognostic value of progesterone receptor after long-term follow-up in primary breast cancer

In a previous study of a series of 105 patients with primary breast cancer we found that the progesterone receptor (PgR) status was an important prognostic factor for early recurrences. 95 patients from the same series were followed-up for a median of 9.5 years and reassessed for the prognostic value of PgR status by univariate and multivariate statistical methods. In univariate analysis, the disease-free interval was only related to the lymph-node status. For overall survival, PgR and combined PgR-ER (oestradiol receptor) status had a prognostic value (P = 0.035 and 0.05, respectively). Moreover, PgR status was found to be discriminant for the survival of the node-negative patients (P = 0.017). In multivariate analysis, ER and PgR status were not significant, indicating that receptor status is not a powerful predictor of the course of breast cancer.

A multicentre study into the reliability of steroid receptor immunocytochemical assay quantification. British Quality Control Group

Qualitative and semiquantitative assessments of oestrogen receptor and progesterone receptor positivity determined on previously immunocytochemically stained slides were performed by eight independent assessors. Concordance between assessments of steroid receptor status was good (24/25, 96%). Interassessor variations in estimates of positive immunostaining levels were high, varying by between 10 and 75% for individual slides. In 2 cases estimates for the same section ranged between 15% nuclei positive and 90% nuclei positive. Wide variations were also recorded for slides stained for progesterone receptors. Results using an assessment procedure combining staining intensity and percentage positivity estimates were also subject to marked discordance. A computerised image analysis system, also used to assess slides gave results similar to the mean manually determined percentage positivity values. It is suggested that quality control of steroid receptor immunocytochemical quantification be considered and that automated image analysis may represent an accurate and valid means of achieving this.

Steroid receptors in breast cancer

Recent advances in steroid receptor structure and function now indicate that oestrogen binds to the oestrogen receptor (ER) molecule at a specific site, denoted region E. This allows binding of the oestrogen-ER complex to DNA via cysteine residues in region C of the ER molecule, which tetrahedrally co-ordinate zinc. This modulates transcription and stimulates cell growth. A number of newly discovered growth factors are also regulated by ER, as is the progesterone receptor. Steroid receptor concentrations in tissues can now be measured on smaller tissue samples using enzyme immunoassay or on cells obtained by fine needle aspiration using monoclonal antibody technology. The prognostic value of steroid receptor is limited, but still constitutes the best marker for predicting response to endocrine therapy. The role of steroid receptors in selecting patients for adjuvant therapy is discussed.

pNR-2/pS2 immunohistochemical staining in breast cancer: correlation with prognostic factors and endocrine response

Expression of the oestrogen-regulated pNR-2/pS2 protein has been studied in paraffin sections of a series of 172 primary breast cancers using an immunohistochemical technique. Positive staining of tumour cells was found in 117 tumours (68%): most of these tumours contained only a small proportion of positive cells. pNR-2 immunohistochemical staining correlated positively and significantly with the presence of oestrogen receptor. Mean percentages of pNR-2 positive cells were lower in tumours from postmenopausal women. Smaller, better differentiated tumours were significantly more likely to stain positively for pNR-2. The percentages of pNR-2 positive tumour cells in primary tumours and synchronously excised lymph node metastases were very similar. pNR-2 expression showed an unexpected positive association with lymph node metastasis. We were unable to find any significant association between pNR-2 immunohistochemical staining and either time to relapse or overall survival. There was a significant association between pNR-2 expression in primary tumours and response to endocrine therapy on relapse: positive pNR-2 immunohistochemical staining in primary tumours is predictive of response to hormonal therapy on relapse.

Epidermal growth factor receptors in intracranial and breast tumours: their clinical significance

A method to determine the binding of epidermal growth factor (EGF) to the particulate fraction of the cell has been established and evaluated using rat liver, human placenta, and tumours of human breast and brain. Little EGF receptor (EGFR) activity was detected in normal or benign tumour tissues except for meningioma (positive in 95% samples), but EGFR were present in 43% of 131 breast tumours and 75% of 55 primary cerebral tumours. Despite the strong inverse correlation between EGFR activity and oestrogen receptors in breast tumours and a tendency for high levels of EGFR activity to be associated with glioblastoma multiforme, analysis showed that EGFR was of little prognostic significance in patients with tumours of either breast or brain.

Is apocrine differentiation in breast carcinoma of prognostic significance?

Apocrine differentiation in human breast cancers has been assessed using immunohistochemistry to detect zinc alpha 2 glycoprotein and the findings related to standard prognostic factors, disease free interval (DFI) and survival in 145 women with early breast cancer. Breast tumour samples from women with a minimum follow-up of 5 years were assessed. Routinely fixed and processed tissue was used throughout. Sixty-six (45%) tumours did not stain with the antibody. Fifty-two (36%) exhibited positive apocrine staining while for 27 (19%) only a few cells were reactive. The presence of apocrine differentiation was unrelated to lymph node status, menstrual status, tumour grade or size, oestrogen receptor (E2R) or progesterone receptor status. However, patients whose tumours exhibited apocrine staining had a shorter disease-free interval (DFI) (P = 0.03) and survival (P = 0.03). A Cox's multiple regression analysis of the data found that the presence of staining added significantly (P = 0.047) to the predictive value of node status (P = 0.0001), menstrual status (P = 0.0001), tumour size (P = 0.0026) and E2R status (P = 0.0014) for patient survival. The other seven prognostic factors tested did not reach significance and were rejected from the model. Apocrine differentiation in breast cancer appears to be an independent predictor of poor prognosis tumours.

Prognostic significance of flow cytometric DNA analysis in node-negative breast cancer patients

Flow cytometric DNA analysis using paraffin-embedded tumor blocks was done retrospectively on 155 node-negative breast cancers. The median duration of follow-up in patients still alive at the time of analysis was 10 years. Tumor aneuploidy was correlated significantly with increased tumor size (P = 0.003) and higher tumor grade (P less than 0.001). No significant correlation between tumor ploidy and patient age was found. Patients with diploid tumors had a significantly improved relapse-free and overall survival compared with patients with aneuploid tumors (P = 0.0001). In a Cox multivariate model with parameters including ploidy, histologic grade, tumor size, and patient age, ploidy (P = 0.02) and tumor size (P = 0.05) emerged as significant independent predictors of overall survival. Only ploidy was independently significant in the analysis of relapse-free survival. In conclusion, the current study indicates that flow cytometric measurement of DNA ploidy is a powerful prognostic indicator in node-negative breast cancer patients.

Relation between apocrine differentiation and receptor status, prognosis and hormonal response in breast cancer

The release of a gross cystic disease fluid protein (GCDFP 15) by tumour explants grown in tissue culture was used to measure apocrine differentiation in 117 women with breast carcinoma. GCDFP 15 was detected by radioimmunoassay in the media from 90% of tumours (range 2-2100 ng/ml, mean 41). Tumour secretion of GCDFP 15 was higher in oestrogen receptor rich (over 20 fmol/mg) tumours (P less than 0.05) but did not correlate with any other prognostic factors or with survival. Response to hormonal therapy was assessable by UICC criteria in 33 women (6 partial responses, 8 stable disease, 19 progression). Responders had significantly higher tumour oestrogen receptor levels (P less than 0.005) but a lower GCDFP 15 secretion than non-responders (P less than 0.02). Apocrine differentiation in breast cancer may be a marker for oestrogen receptor positive tumours that do not respond to hormonal therapy.

Expression of glutathione S-transferase B1, B2, Mu and Pi in breast cancers and their relationship to oestrogen receptor status

The concentrations of glutathione S-transferase (GST) B1 and B2 (Alpha), Pi and Mu have been measured by radioimmunoassay in cytosols from 28 oestrogen receptor (ER) rich an 30 ER-poor breast tumours. GST B1, B2 and Pi was detected in all 58 breast tumour cytosols whilst GST Mu was found in only 28. Of the GSTs, Pi was expressed most strongly in all cytosols and the concentration was significantly higher in ER-poor tumour cytosols than in ER-rich tumours (P less than 0.01). As with GST Pi, the highest levels of GST B1 and GST B2 were found in ER-poor tumour cytosols; the levels of GST B1 and GST B2 were positively correlated (r = 0.66, P less than 0.001). No quantitative or qualitative association was found between ER status and GST Mu which was expressed in 46% of ER-rich and 50% of ER-poor tumour cytosols. No relationship could be found between GST expression and age, menopausal status, lymph node involvement or tumour T stage in the subgroup of patients in whom this information was available. These data suggest that a common mechanism is responsible for GST induction in ER-poor tumours and that the nulled Mu phenotype has no increased susceptibility to developing breast cancer.

Response to endocrine manipulation and oestrogen receptor concentration in large operable primary breast cancer

Forty-three patients with large (greater than or equal to 4 cm) but operable carcinoma of the breast have been treated by endocrine manipulation before definitive local surgery. This has allowed the study of the relationship between response to therapy and pretreatment oestrogen receptor (ER) concentration, as measured by a dextran-coated charcoal adsorption method. Premenopausal patients (17) were treated by surgical (4) or medical (13) oophorectomy. Post-menopausal patients (26) received either tamoxifen (10) or an aromatase inhibitor (16). Response was assessed from statistical analysis of the changes in tumour size. On completion of 12 weeks of endocrine therapy, there was significant regression of tumour size in 18 of the 43 patients. All 18 patients had tumours with ER concentrations of greater than or equal to 20 fmol mg-1 cytosol protein. Conversely all patients except one progressing on treatment had tumours with ER concentrations of less than 20 fmol mg-1 cytosol protein. This relationship applied for both premenopausal and post-menopausal patients. The overall response rate of patients with tumours of ER concentration greater than or equal to 20 fmol mg-1 cytosol protein was 60%.

Measurement of oestrogen receptor mRNA levels in human breast tumours

A sensitive single-stranded hybridisation probe for the oestrogen receptor mRNA was synthesised using T3 polymerase from oestrogen receptor cDNA cloned in the Bluescript vector. This probe was used to measure oestrogen receptor mRNA in total RNA extracted from breast tumours. Oestrogen receptor mRNA was detected in 41 of 47 (87%) tumours whereas cytosolic oestrogen receptor protein was detected in only 18 out of 39 (46%). There was a significant correlation between the levels of the oestrogen receptor, as measured by 3H-oestradiol binding, and the oestrogen receptor mRNA. Oestrogen receptor mRNA was detected in 15 of the 21 tumours that did not contain detectable oestrogen receptor protein. This suggests that detection of the mRNA is a more sensitive means for establishing oestrogen receptor status than the radioligand oestrogen receptor assay. Oestrogen receptor mRNA was found in all histological tumour types examined. Its level was related to tumour differentiation. All the tumours that did not contain oestrogen receptor mRNA and most of the tumours that contained only low levels of oestrogen receptor mRNA were classified as grade III according to Bloom and Richardson: the median of the oestrogen receptor mRNA levels was significantly lower in this group.