Hormone receptor status of a contralateral breast cancer is independent of the receptor status of the first primary in patients not receiving adjuvant tamoxifen.

PURPOSE: To determine whether the hormone receptor status of the primary breast cancer (PBC) is predictive of the hormone receptor status of the subsequent contralateral breast cancer (CBC). PATIENTS AND METHODS: We identified patients in our database with known estrogen receptor (ER; n = 193) and/or progesterone receptor (PgR; n = 178) status in their PBC and in their subsequent CBC. One hundred twenty-six of these patients had received no adjuvant therapy, 34 had received adjuvant tamoxifen, and 33 had received adjuvant chemotherapy alone. The median interval between the first diagnosis of PBC and the development of the subsequent CBC was 3 years. ER and PgR assays were assessed biochemically in two central reference laboratories using identical quality-controlled ligand-binding methods. RESULTS: Among systemically untreated patients (n = 126), 88% of patients with ER-positive PBC and 75% of patients with ER-negative PBC developed an ER-positive CBC (P = .11). Among the tamoxifen-treated patients, those with an ER-positive PBC were almost equally likely to develop an ER-positive (47%) or ER-negative (53%) CBC (P = .99). PgR status was similar. In the untreated group (n = 112), 59% of patients with a PgR-positive PBC and 66% with a PgR-negative PBC developed a PgR-positive CBC (P = .48). Among tamoxifen-treated patients (n = 33), 50% of patients with a PgR-positive PBC versus 27% of patients with a PgR-negative PBC developed a PgR-positive CBC (P = .28). CONCLUSION: ER and PgR status of the primary tumor does not predict the hormone receptor status of the subsequent CBC in the absence of selective pressure of adjuvant therapy. Thus, other reasons should be considered to clarify the failure of tamoxifen to reduce the incidence of CBC in patients with a receptor-negative PBC.     

Pattern of hormone receptor status of secondary contralateral breast cancers in patients receiving adjuvant tamoxifen.

In breast cancer patients receiving adjuvant tamoxifen after unilateral treatment, contralateral breast cancer (CBC) is extremely rare. As a result, only limited data are available on the hormone receptor status of CBCs evolving in tamoxifen-treated patients. The aim of our investigation was to evaluate the pattern of hormone receptor status of CBCs in patients treated with adjuvant tamoxifen at our institution. Material was collected from 35 patients. We have found that 27 of the 35 patients included into our investigation developed an estrogen receptor (ER)-positive CBC despite adjuvant tamoxifen. Seven ER-positive CBCs occurred after tamoxifen had been discontinued, and 20 patients developed an ER-positive CBC while receiving tamoxifen. Notably, 80% of these CBCs displayed moderate-to-strong levels of ER. In our opinion, the selection of ER-negative CBCs, which has previously been implicated to be the pivotal mechanism of tumor escape of CBCs evolving in tamoxifen-treated patients, is only one mechanism of tumor escape in patients receiving antiestrogen treatment. The emergence of ER-positive CBCs in the majority of tamoxifen-treated patients suggests that alternative escape mechanisms may be equally relevant. These include the emergence of ER-positive CBCs that display tamoxifen-dependent growth properties, the selection of CBCs that are tamoxifen resistant because of ER mutations with altered ER function, and, finally, the selection of ER-positive CBCs that overexpress c-erbB2.     

Prognostic significance of progesterone receptor levels in estrogen receptor-positive patients with metastatic breast cancer treated with tamoxifen: results of a prospective Southwest Oncology Group study.

PURPOSE: Southwest Oncology Group (SWOG) protocol 8228 is a prospective trial designed to investigate the prognostic significance of progesterone receptor (PgR) levels in estrogen receptor (ER)-positive breast cancer patients who were treated with tamoxifen. This study was undertaken because the value of PgR measurements in advanced breast cancer had been assessed previously only in studies that were small, retrospective, or included heterogeneously treated patients. METHODS: Receptor assays were performed only in the laboratories that met strict quality control guidelines. Of the 398 patients entered, 342 patients were eligible and assessable for the study end points of objective clinical response, time to treatment failure, and overall survival. RESULTS: Multivariate analysis shows that elevated PgR levels significantly and independently correlated with increased probability of response to tamoxifen, longer time to treatment failure, and longer overall survival. Overall response rate (defined as complete response [CR], partial response [PR], or stable disease [SD] for greater than 6 months) in this trial was 54%. Response rates to tamoxifen were 43%, 53%, and 61% in subsets of patients with less than 10, 10 to 99, and more than 100 fmol/mg PgR, respectively. Exploratory subset analysis using PgR and other prognostic variables identified ER-positive patient subsets with response rates to tamoxifen ranging from 24% (premenopausal patients) to 86% (postmenopausal patients with ER greater than 38 and PgR greater than 329 fmol/mg). No groups of ER-positive patients were identified who had such a low response rate as to absolutely preclude considering the use of tamoxifen. Multivariate analysis showed the independent, statistically significant predictors were: for response to tamoxifen, menopausal status, PgR, and ER; for time to treatment failure, menopausal status, disease-free interval (DFI), PgR, and ER; and for overall survival DFI, PgR, ER, site of disease, and history of adjuvant therapy. CONCLUSION: We conclude that knowledge of PgR levels together with other clinical information can improve the pretreatment assessment of ER-positive breast cancer patients with metastatic disease.     

Tumor biology in estrogen receptor-positive,human epidermal growth factor receptor type 2-negative breast cancer: Mind the menopausal status

Breast cancer is not one disease, but can be categorized into four major molecular subtypes according to hormone receptor [estrogen receptor (ER) and progesterone receptor (PgR)] and human epidermal growth factor receptor type 2 (HER2) expression status. Ki67 labeling index and/or multigene assays are used to classify ER-positive, HER2-negative breast cancer into luminal A and luminal B (HER2-negative) subtypes. To date, most studies analyzing predictive or prognostic factors in ER-positive breast cancer have been performed in postmenopausal women, mainly using patients and samples in adjuvant aromatase inhibitor trials. In contrast, even the clinical roles of PgR and Ki67 have been little analyzed so far in premenopausal women. PgR is one of the estrogen-responsive genes, and it has been reported that plasma estradiol levels are related to expression levels of estrogen-responsive genes including PGR in ER-positive breast cancer. In this article, biological differences, especially differences in expression of PgR and Ki67 in ER-positive breast cancer between pre- and postmenopausal women are discussed. Clinical roles of PgR and Ki67 in ER-positive breast cancer differ between pre- and postmenopausal women. We suggest that the mechanisms of development and estrogen-dependent growth of ER-positive breast cancer might differ according to menopausal status.     

C–X–C ligand 10 and C–X–C receptor 3 status can predict tamoxifen treatment response in breast cancer patients

To investigate the expression levels of CXCL10 and CXCR3 in tumors from breast cancer patients randomized to adjuvant tamoxifen treatment or no endocrine treatment, in order to further study the connection to prognosis and prediction of tamoxifen treatment outcome. Immunohistochemistry on tissue microarrays from 912 breast cancer patients randomized to tamoxifen or no endocrine treatment. CXCR3 status was found to be a prognostic tool in predicting distant recurrence, as well as reduced breast cancer-specific survival. In patients with estrogen receptor (ER)-positive tumors, tumors with strong CXCL10 levels had improved effect of tamoxifen treatment in terms of local recurrence-free survival [risk ratio (RR) 0.46 (95 % CI 0.25–0.85, P = 0.01)] compared with patients with tumors expressing weak CXCL10 expression. Further, patients with ER-positive tumors with strong CXCR3 expression had an improved effect of tamoxifen in terms of breast cancer-specific survival [RR 0.34 (95 % CI 0.19–0.62, P < 0.001)] compared with the group with weak CXCR3 levels [RR 1.33 (95 % CI 0.38–4.79, P = 0.65)]. We show here for the first time that CXCL10 and CXCR3 expression are both predictors of favorable outcome in patients treated with tamoxifen.     

AIB1 is a predictive factor for tamoxifen response in premenopausal women

BackgroundClinical trials implicate the estrogen receptor (ER) coactivator amplified in breast cancer 1 (AIB1) to be a prognostic and a treatment-predictive factor, although results are not unanimous. We have further investigated this using a controlled randomised trial of tamoxifen versus control.Materials and methodsA total of 564 premenopausal women were entered into a randomised study independent of ER status. Using a tissue microarray, AIB1 and ER were analysed by immunohistochemistry.ResultsAIB1 scores were obtained from 349 women. High AIB1 correlated to factors of worse prognosis (human epidermal growth factor receptor 2, Nottingham histological grade 3, and lymph node metastases) and to ER negativity. In the control arm, high AIB1 was a negative prognostic factor for recurrence-free survival (RFS) (P = 0.02). However, ER-positive patients with high AIB1 responded significantly to tamoxifen treatment (P = 0.002), increasing RFS to the same level as for systemically untreated patients with low AIB1. Although ER-positive patients with low AIB1 had a better RFS from the beginning, this was not further improved by tamoxifen (P = 0.8).ConclusionsIn the control group, high AIB1 was a negative prognostic factor. However, ER-positive patients with high AIB1 responded significantly to tamoxifen. This implicates high AIB1 to be an independent predictive factor of improved response to tamoxifen and not, as has previously been discussed, a factor predicting tamoxifen resistance.     

Low-dose tamoxifen in the treatment of breast ductal intraepithelial neoplasia: results of a large observational study

Background: Tamoxifen's cost–benefit ratio for breast ductal intraepithelial neoplasia (DIN) is unclear. Since low-dose tamoxifen showed a favorable modulation of breast cancer biomarkers in phase II trials, a monoinstitutional cohort of women with DIN treated with low-dose tamoxifen or no systemic treatment was analyzed.Patients and methods: A total of 309 patients with DIN received low-dose tamoxifen as part of institutional guidelines and were compared with 371 patients with DIN who received no systemic treatment after surgery.Results: Women with estrogen receptor (ER)/progesterone receptor (PgR) >50% DIN who were not treated had a higher incidence of breast events than women on tamoxifen [hazard ratio (HR) 1.76; 95% confidence interval (CI) 1.00–3.12] or women with ER/PgR <50% DIN (HR 1.72; 95% CI 1.14–2.58). Among untreated patients with ER >50% DIN, recurrence was higher in PgR ≥50% DIN than in PgR <50% DIN, whereas it was similar among low PgR (<50%) DIN against which tamoxifen had no effect. No difference in endometrial cancer incidence was noted.Conclusions: High ER and especially high PgR expression is a significant adverse prognostic indicator of DIN, and low-dose tamoxifen appears to be an active treatment. Women with low-expression ER or PgR DIN do not seem to benefit from tamoxifen. A definitive clinical trial is warranted.     

Phosphorylated c-Src in the nucleus is associated with improved patient outcome in ER-positive breast cancer

Elevated c-Src protein expression has been shown in breast cancer and in vitro evidence suggests a role in endocrine resistance. To investigate whether c-Src is involved in endocrine resistance, we examined the expression of both total and activated c-Src in human breast cancer specimens from a cohort of oestrogen receptor (ER)-positive tamoxifen-treated breast cancer patients. Tissue microarray technology was employed to analyse 262 tumour specimens taken before tamoxifen treatment. Immunohistochemistry using total c-Src and activated c-Src antibodies was performed. Kaplan–Meier survival curves were constructed and log-rank test were performed. High level of nuclear activated Src was significantly associated with improved overall survival (P=0.047) and lower recurrence rates on tamoxifen (P=0.02). Improved patient outcome was only seen with activated Src in the nucleus. Nuclear activated Src expression was significantly associated with node-negative disease and a lower NPI (P<0.05). On subgroup analysis, only ER-positive/progesterone receptor (PgR)-positive tumours were associated with improved survival (P=0.004). This shows that c-Src activity is increased in breast cancer and that activated Src within the nucleus of ER-positive tumours predicts an improved outcome. In ER/PgR-positive disease, activated Src kinase does not appear to be involved in de novo endocrine resistance. Further study is required in ER-negative breast cancer as this may represent a cohort in which it is associated with poor outcome.     

The prognostic biomarkers HOXB13, IL17BR, and CHDH are regulated by estrogen in breast cancer.

PURPOSE: We previously identified three genes, HOXB13, IL17BR, and CHDH, that strongly predict clinical outcome in estrogen receptor (ER)-positive breast cancer patients receiving tamoxifen monotherapy. The biological mechanisms linking these genes to estrogen signaling and tamoxifen response in breast cancer remain to be determined. EXPERIMENTAL DESIGN: In a consecutive series of 148 ER-positive and ER-negative breast cancers, HOXB13, IL17BR, and CHDH gene expression was measured by quantitative real-time PCR and correlated with ER, PR, and HER2 expression. The role of estrogen and ER in the regulation of these three genes was assessed in several ER-positive and ER-negative breast cancer cell lines. RESULTS: In primary breast tumors, HOXB13 expression correlated negatively, and IL17BR and CHDH expression correlated positively, with ER status, and all three genes exhibited an ER-dependent correlation pattern with HER2 status that differs from PR and PS2, two canonical estrogen-regulated genes. Results using breast cancer cell lines show that these genes are regulated by estradiol in an ER-dependent manner, and that this regulation is abrogated by tamoxifen. CONCLUSIONS: HOXB13, IL17BR, and CHDH are estrogen-regulated genes, but their pattern of correlation with known positive (ER, PR) and negative (HER2) predictors of tamoxifen response differs from canonical ER signature genes. These results provide a biological rationale for the prognostic utility of these three genes in early-stage ER-positive breast cancer and for their potential to predict anti-estrogen resistance.     

Role of steroid hormone receptors as prognostic factors in primary breast cancer

A review and update of published studies on estrogen receptor (ER) and progesterone receptor (PgR) as prognostic factors in breast cancer support the following conclusions. In stage I breast cancer, the lack of ER seems to be the most important factor for predicting earlier recurrence and poorer survival. In stage II breast cancer, PgR content appears to be better than ER content in predicting disease-free survival and PgR content is as important as ER content in predicting overall survival. The benefits of adjuvant endocrine therapy are better predicted by the presence or absence of PgR than by the presence or absence of ER. Measurement of proliferative activity (S-phase DNA) by thymidine labeling or flow cytometry and of aneuploidy by flow cytometry also provides prognostic information. The strong correlations between tumor receptor content, percent S-phase cells, and aneuploidy suggest that these measurements in concert might identify a subset of stage I breast cancer patients at increased risk for recurrence, who would thus be potential candidates for adjuvant therapy.     

EGFRvIII‐induced estrogen‐independence,tamoxifen‐resistance phenotype correlates with PgR expression and modulation of apoptotic molecules in breast cancer

The tumor‐specific, ligand‐independent, constitutively active epidermal growth factor receptor (EGFR) variant, EGFRvIII, remains understudied in breast cancer. Here, we report that expression of EGFRvIII in the ErbB‐2‐overexpressing, estrogen‐dependent MDA‐MB‐361 breast cancer cell line resulted in significant estrogen‐independent tumor growth in ovariectomized, athymic nude mice in comparison to MDA‐MB‐361/wt cells. MDA‐MB‐361/vIII breast cancer cells maintained estrogen‐induced tumor growth, but were tamoxifen‐resistant in the presence of estrogen, while MDA‐MB‐361/wt cells had a significant reduction in tumor growth in the presence of estrogen and tamoxifen. Tamoxifen alone did not have a significant effect on EGFRvIII‐mediated estrogen‐independent tumor growth. Constitutive signaling from the EGFRvIII receptor resulted in an increased activation of both the Akt and MAPK pathways. Compared to estrogen‐dependent, tamoxifen‐sensitive MCF‐7/vIII breast cancer cells, which had unchanged levels of ERα, but an increase in progesterone receptor (PgR) in comparison to MCF‐7/wt cells, MDA‐MB‐361/vIII cells had a reduction in ERα expression as well as a more pronounced reduction in PgR compared with MDA‐MB‐361/wt cells. EGFRvIII expression was also significantly associated with an absence of PgR protein in invasive human breast cancer specimens. Alterations of proapoptotic proteins and antiapoptotic proteins were observed in EGFRvIII transfectants. In conclusion, constitutive signaling through EGFRvIII and its downstream effector proteins crosstalks with the ERα pathway, resulting in loss of PgR expression and alterations in the apoptotic pathway, which may result in the estrogen‐independent, tamoxifen‐resistant phenotype conferred to EGFRvIII‐expressing breast cancer cells. © 2009 UICC     

Targeting c-Src kinase enhances tamoxifen’s inhibitory effect on cell growth by modulating expression of cell cycle and survival proteins

Purpose Many studies have implicated the non-receptor tyrosine kinase c-Src in the development and metastatic progression of many types of cancer. In breast cancer, c-Src has been proposed to mediate the actions of estrogen in cell cycle progression. Methods In this study we investigated the interaction between c-Src inhibition and estrogen receptor (ER) function using the ER-positive and tamoxifen-sensitive MCF-7 breast cancer cells. Results Pharmacological inhibition of c-Src blocked estrogen-dependent proliferation in MCF-7 cells and enhanced the inhibitory effects of tamoxifen or estrogen-deprivation on cell growth. Maximum inhibition (95%) of cell growth was obtained when tamoxifen and c-Src blockade were combined. Inhibition of c-Src kinase decreased levels of the ER targets c-Myc and cyclin D1 expression but not of Bcl-2. Nevertheless, blocking c-Src kinase in tamoxifen-treated MCF-7 cells led to apoptosis. Inhibition of c-Src kinase altered the ratio of Mcl-1 isoforms in favor of cell death whereas expression of the proapoptotic molecules Bad, Bak, and Bax was not altered. Surprisingly, blocking ER function increased the levels of Bad phosphorylation at serine 112 (BadpS112), an inactive (nonapoptotic) form of Bad. This inactivation of Bad upon ER blockade seemed to depend on c-Src function as chemical inhibition of c-Src kinase reduced BadpS112 levels in cells with impaired ER function but not in estrogen-treated cells. Conclusion These results indicate a crucial role for c-Src kinase in the survival of ER-positive breast cancer cells only when ER function is blocked. Therefore, this study suggests that targeting simultaneously c-Src and ER may effectively inhibit growth of ER-positive breast cancer.     

Role of biologic markers in patient selection and application to disease prevention

Aromatase inhibitors (AIs) are now under investigation for the treatment of early stage breast cancer and for disease prevention as alternatives to standard treatment with tamoxifen. Currently identified genetic risk factors of breast cancer include BRCA-1/BRCA-2 mutations, ATM mutations, and history of high estrogen levels, as evidenced by plasma analyses and/or dense bones. To date, estrogen receptor (ER) and progesterone receptor (PgR) status has predictive value for determining response to therapy in patients with hormone receptor-positive breast cancer (ER+ and/or PgR+ tumors). Recent studies have shown AIs to be safer and more effective than tamoxifen in postmenopausal women with advanced disease. Some data suggest that letrozole may be a more effective treatment than tamoxifen for patients with ER+ and/or PgR+ early breast cancers expressing ErbB-1 and/or ErbB-2. Changes in cell proliferation markers (e.g., S-phase fraction and Ki67 antigen), plasma lipid levels, and the bone resorption marker C-terminal peptide are biomarkers that have been evaluated for preventive and prognostic value in breast cancer patients and normal volunteers. Results from biomarker screens can be used to define inclusion criteria for clinical trials and eventually to individualize treatment. Gene expression profiling (microarray analysis), i.e., genomic and proteomic studies, will probably advance the discovery of new biomarkers for breast cancer prevention and treatment.     

miR-181a表达水平与ER阳性乳腺癌对内分泌治疗敏感性的关系

目的:研究miR-181a表达水平与雌激素受体（estrogen receptor,ER）阳性乳腺癌对内分泌治疗敏感性之间的关系。方法:采用梯度递增法诱导乳腺癌他莫昔芬耐药细胞株,利用集落形成实验检测细胞对他莫昔芬的敏感性。利用RT-PCR法检测miR-181a表达的情况,利用KM-plotter分析miR-181表达与乳腺癌患者预后之间的关系。结果:我们成功的诱导了MCF-7他莫昔芬继发耐药细胞株TAM-R。RT-PCR分析结果显示:他莫昔芬继发耐药的TAM-R细胞株及原发他莫昔芬耐药BT474细胞株中miR-181a的表达水平均显著高于对他莫昔芬敏感的MCF-7细胞株。生存分析结果显示:miR-181a的表达水平与ER阴性乳腺癌患者的总生存无关,但在ER阳性乳腺癌中miR-181a表达高的患者总生存明显差于miR-181a低表达者。进一步分析结果显示:在ER阳性但未接受内分泌治疗的乳腺癌患者中miR-181a表达与总生存无关,但在ER阳性且接受过内分泌治疗的乳腺癌患者中miR-181a高表达者总生存显著差于miR-181a低表达者。结论:miR-181a高表达ER阳性乳腺癌患者对内分泌治疗敏感性差,miR-181a可能是预测ER 阳性乳腺癌对内分泌治疗敏感性的指标。     

Association of ErbB1–4 expression in invasive breast cancer with clinicopathological characteristics and prognosis

Background

Human epidermal growth factor receptor type 2 (Her2)/ErbB2 plays a key role in the initiation and progression of invasive breast cancer. However, the prognostic relevance to breast cancer patients of the other ErbB family members has long been a matter of debate.

Methods

In a series of 250 primary invasive breast cancer patients, we performed a comprehensive analysis of ErbB1–4 at the levels of mRNA expression and gene copy number using real-time quantitative PCR. The relationship between the status of ErbB1–4 and the clinicopathological characteristics or prognosis was evaluated.

Results

The mRNA expression of ErbB2, but not the other ErbB genes, was significantly correlated to copy number (P = 0.0005). ErbB3 and ErbB4 mRNA expression were positively correlated to each other (P < 0.0001). The mRNA expression of ErbB1/2 was inversely correlated to estrogen receptor (ER) and progesterone receptor (PgR) positivity, although mRNA expression of ErbB3/4 was positively correlated to ER and PgR positivity. Kaplan-Meier survival analysis showed that ErbB1 mRNA expression was associated with reduced survival. Neither ErbB2 nor ErbB3 mRNA expression had any association with survival, because half of the patients with Her2-positive tumors were treated with trastuzumab. High ErbB4 mRNA expression showed good prognosis with respect to breast cancer-specific survival

Conclusions

ErbB3 and ErbB4 mRNA expression, as well as well as that of ErbB1 and ErbB2, could be histopathological factors. ErbB3 mRNA was highly expressed in ER-positive tumors and has controversial prognostic value. ErbB4 mRNA expression was well correlated with ER positivity and good prognosis, indicating that ErbB4 may contribute to ER-dependent growth.     

A 3-gene proliferation score (TOP-FOX-67) can re-classify histological grade-2, ER-positive breast cancers into low- and high-risk prognostic categories

The goal of this study was to assess the prognostic value of a 3-gene (TOP2A, FOXM1, and MKI67) proliferation score and use it to risk stratify grade-2, estrogen receptor (ER)-positive breast cancers into low- and high-risk groups. We used 4 different breast cancer gene expression datasets including two cohorts of patients who received no systemic adjuvant therapy (Mainz: n = 206, TRANSBIG: n = 134) and two other cohorts that received adjuvant tamoxifen (JBI: n = 227, MDACC/SET: n = 192). We compared individual and combined expression values of the 3 genes between grade 1, 2, and 3 tumors and plotted distant metastasis-free survival (DMFS) curves by the 3-gene score for grade-2 cancers. We compared the prognostic value of the 3-gene score to the Genomic Grade Index (GGI). The individual and combined expression of TOP2A, FOXM1, and MKI67 were significantly different between the 3 histological grade groups with the highest expression in grade-3 and the lowest in grade-1 cancers. Expression levels were variable in grade-2 cancers. Grade-2 tumors with high expression of the 3 genes (>median) showed significantly worse DMFS in one prognostic and one tamoxifen-treated set and showed a similar but non-significant trend for worse survival in the remaining two datasets. The 3-gene score performed equally well in risk stratification as the GGI. A 3-gene proliferation score shows similar prognostic value as the GGI in ER-positive, grade-2 cancers and may serve as basis for a PCR-based assay that could aid prognostic prediction for clinically intermediate-risk cancers.     

Immunohistochemical BAG1 expression improves the estimation of residual risk by IHC4 in postmenopausal patients treated with anastrazole or tamoxifen: a TransATAC study

BAG1 is a multifunctional anti-apoptotic protein located on chromosome 9q12, which binds to Bcl-2. BAG1 is present as a separate module in the GHI-RS 21-gene panel. It may provide additional prognostic information as an immunohistochemical marker when added to IHC4. Analysis of BAG1 was performed on archival tumour blocks from patients from the anastrozole and tamoxifen arms of the ATAC trial of 5 years endocrine therapy in postmenopausal women with oestrogen receptor (ER)-positive primary breast cancer. Staining was scored separately as nuclear or cytoplasmic. Statistical analyses were performed on data from median 10-year follow-up with distant recurrence as primary endpoint. Data on both nuclear and cytoplasmic BAG1 as well as the IHC4 markers (ER, PgR, HER2 and Ki67) were available on 963 ER-positive cases of which 860 were HER2-negative. Cytoplasmic and nuclear BAG1 were highly correlated (Spearman r = 0.79, p < 00001). Women with higher BAG1 expression developed 30 % fewer distant recurrences compared to those with low expression. Nuclear BAG1 contributed significantly to the clinical and IHC4 models with added information being greater in node-positive cases. Similar results were seen if all recurrences were the endpoints. BAG1 expression provides significant prognostic information when added to the classical clinicopathological parameters and IHC4, particularly in node-positive patients.     

Measurement of steroid hormone receptors in breast cancer patients on tamoxifen

Summary Estrogen (ER) and progesterone receptor (PgR) positive breast tumors often respond to tamoxifen, but ultimately progress as they become tamoxifen resistant. An accurate assessment of receptor status in specimens from tamoxifen-resistant patients could help to understand potential mechanisms of resistance and to predict response to second line hormonal therapies. However, since tamoxifen itself can affect ER and PgR determinations, assay results can be misleading. We measured ER and PgR by both ligand binding (LBA) and immunohistochemical (IHC) assays in 34 tumors from patients on tamoxifen, 30 of whom were displaying resistance to the drug. These tumors were classified into several receptor phenotypes. Eleven patients, 8 of whom were clearly progressing, expressed both receptors while on tamoxifen. ER was significantly less often negative when measured by IHC, suggesting that ER status by LBA was falsely negative in this group due to receptor occupancy by tamoxifen. Six patients had no detectable ER by LBA or IHC but still expressed PgR. The presence of PgR suggests that ER could still be functional, though undetectable, in these tumors, or that PgR is constitutively expressed by them. Finally, 12 patients were ER and PgR-negative by both assays, suggesting hormonal independence as the mechanism for resistance in this group. In a subset of patients with receptor assays both prior to tamoxifen and at the time of progression while taking the drug, we found that most ER-positive tumors converted to an apparent ER-negative status when assayed by LBA, while PgR status frequently remained unchanged. The continued expression of ER and/or PgR in many patients with tumor progression on tamoxifen indicates that mechanisms for resistance other than receptor loss are common in breast cancer.Deceased     

Pathological features of breast cancer response following neoadjuvant treatment with either letrozole or tamoxifen

Morphological characteristics, grading features, proliferation marker MIB1, apoptosis (by Tdt-mediated duTP-biotin nick-end labelling (TUNEL)), Bcl-2 expression, oestrogen receptor (ER) and progesterone receptor (PgR) status were compared in ER-positive breast cancers before and after 3 months of neoadjuvant therapy with either letrozole or tamoxifen. Daily treatment was with letrozole 2.5 mg (12 patients) or 10 mg (12 patients), or with tamoxifen 20 mg(24 patients). Letrozole treatment was associated with a pathological response in 17 of 24 (71%) patients. The predominant change in grading features was a decrease in mitosis, and the expression of MIB1 was reduced in all of the 22 evaluable cases. Whilst only marginal changes were observed in ER expression following letrozole therapy, PgR reactivity was reduced in 20 of 21 evaluable cases which were initially PgR-positive, becoming undetectable in 16 patients. Tamoxifen treatment was associated with pathological response in 15 of 24 (63%) tumours. In contrast to letrozole, the dominant change in grading feature was an increase in tubule formation, ER score was markedly reduced in most cases, and the most common effect on PgR was an increased expression. Following treatment with either tamoxifen or letrozole, variable effects were observed on the apoptotic index and expression of Bcl-2. These results indicate that both letrozole and tamoxifen have marked influences on the pathological features of breast cancer during neoadjuvant therapy. However, the effects of the two agents varied such that the phenotypes of letrozole- and tamoxifen-treated tumours differ markedly. Effects on clinical, pathological and biological endpoints were frequently disconcordant--future studies will therefore require the evaluation of multiple parameters in order to fully assess tumour response.     

Activation of Akt, mTOR, and the estrogen receptor as a signature to predict tamoxifen treatment benefit

The frequent alterations of the PI3K/Akt/mTOR-growth signaling pathway are proposed mechanisms for resistance to endocrine therapy in breast cancer, partly through regulation of estrogen receptor α (ER) activity. Reliable biomarkers for treatment prediction are required for improved individualized treatment. We performed a retrospective immunohistochemical analysis of primary tumors from 912 postmenopausal patients with node-negative breast cancer, randomized to either tamoxifen or no adjuvant treatment. Phosphorylated (p) Akt-serine (s) 473, p-mTOR-s2448, and ER phosphorylations-s167 and -s305 were evaluated as potential biomarkers of prognosis and tamoxifen treatment efficacy. High expression of p-mTOR indicated a reduced response to tamoxifen, most pronounced in the ER+/progesterone receptor (PgR) + subgroup (tamoxifen vs. no tamoxifen: hazard ratio (HR), 0.86; 95 % confidence interval (CI), 0.31–2.38; P = 0.78), whereas low p-mTOR expression predicted tamoxifen benefit (HR, 0.29; 95 % CI, 0.18–0.49; P = 0.000002). In addition, nuclear p-Akt-s473 as well as p-ER at -s167 and/or -s305 showed interaction with tamoxifen efficacy with borderline statistical significance. A combination score of positive pathway markers including p-Akt, p-mTOR, and p-ER showed significant association with tamoxifen benefit (test for interaction; P = 0.029). Cross-talk between growth signaling pathways and ER-signaling has been proposed to affect tamoxifen response in hormone receptor-positive breast cancer. The results support this hypothesis, as an overactive pathway was significantly associated with reduced response to tamoxifen. A clinical pre-treatment test for cross-talk markers would be a step toward individualized adjuvant endocrine treatment with or without the addition of PI3K/Akt/mTOR pathway inhibitors.