Proliferation markers and survival in early breast cancer: a systematic review and meta-analysis of 85 studies in 32,825 patients

Distribution, clinicopathologic features and survival of breast cancer subtypes in Southern China

Breast cancer research and treatment by different subtypes is an inevitable trend. We investigated the clinicopathologic features and outcomes of different breast cancer subtypes in Southern China. A total of 5809 patients with invasive ductal carcinomas were identified. Immunohistochemical (IHC) markers for estrogen receptor (ER), progesterone receptor (PR), Her2/neu, and Ki-67 proliferation index were used to classify cases into five molecular subtypes. Clinicopathologic characteristics and survival rates were analyzed retrospectively. Of all patients, 31.1% were luminal A subtype, 30.4% luminal B (high Ki-67), 13.1% luminal B (Her2/neu+), 9.0% Her2/neu and 16.5% triple negative subtype. Luminal B (high Ki-67) presented primarily in premenopausal patients with the lowest average age (43.0 years). Her2/neu positive tumors were more closely associated with aggressive features including increased tumor size, positive lymph node status and lymphvascular invasion (LVI). Triple negative subtype was characterized by poorer histologic grade. Her2/neu positive cases had presented the worst 5-year disease-free survival (DFS) and overall survival (OS). Multivariate analyses of OS and DFS suggested that there were different negative prognostic factors for the five subtypes. The benefit of the cyclophosphamide, methotrexate, and 5-fluorouracil (5FU) (CMF) regimen was equal to that of anthracycline-based and Taxane-based regimens for patients with luminal A subtype and triple negative subtype, but inferior to anthracycline-based and Taxane-based regimens for those with two luminal B subtypes and Her2/neu subtype. The prognostic significance of traditional markers may differ among subtypes. This study revealed the distinct clinicopathologic characteristics, systemic therapy benefits, prognostic factors and survival rate among different breast cancer subtypes.

Thymidine kinase 1 upregulation is an early event in breast tumor formation

Prognostic markers play an important role in our understanding of tumors and how to treat them. Thymidine kinase 1 (TK1), a proliferation marker involved in DNA repair, has been shown to have independent prognostic potential. This prognostic potential includes the novel concept that upregulation of serum TK1 levels is an early event in cancer development. This same effect may also be seen in tumor tissue. In order to demonstrate that TK1 upregulation is an early event in tumor tissue formation, tissue arrays were obtained and stained for TK1 by immunohistochemistry. Using a progressive breast tissue array, precancerous tissue including breast adenosis, simple hyperplasia, and atypical hyperplasia stained positive for TK1 expression. Different stages of breast carcinoma tissue also stained positive for TK1 including nonspecific infiltrating duct, infiltrating lobular, and infiltrating duct with lymph node metastasis carcinomas. This indicates that TK1 upregulation is an early event in breast carcinoma development, and may be useful in identifying precancerous tissue. Further work is needed to better understand the differences seen between TK1 positive and negative tissues.

Immunohistochemical Ki67 labeling index has similar proliferation predictive power to various gene signatures in breast cancer

The objective of this study was to examine the association between the immunohistochemical Ki67 labeling index (IHC Ki67), Ki67 mRNA expression level, and first-generation gene signatures in a cohort of breast cancer patients. We assessed associations between IHC Ki67 and first-generation gene signatures in a panel of 39 tumor samples, using an oligonucleotide microarray. Gene expression analyses included Ki67 alone (MKi67), 21-gene signature, mitosis kinome score signature, and genomic grade index. Correlation coefficients were calculated by Spearman's rank correlation test. In all cases, IHC Ki67, MKi67, and three genetic markers were highly correlated (ρ, 0.71-0.97). Estrogen receptor (ER)-positive cases showed strong correlations between IHC Ki67 and other signatures (ρ, 0.79-0.83). The ER-negative cases showed slightly lower correlations (ρ, 0.58-0.73). In ER-positive cases, the low IHC Ki67 group showed significantly longer relapse-free survival than the high IHC Ki67 group (P = 0.007). This difference was confirmed by multivariate analysis. Our data indicate that IHC Ki67 shows similar predictive power for proliferation in ER-positive cancers as genomic markers. Further study of IHC Ki67 is needed to define prognostic factors and predictive factors for chemotherapy using central laboratory assessment.

Prognostic value of molecular subtypes, ki67 expression and impact of postmastectomy radiation therapy in breast cancer patients with negative lymph nodes after mastectomy

PURPOSE

To determine whether Ki67 expression and breast cancer subtypes could predict locoregional recurrence (LRR) and influence the postmastectomy radiotherapy (PMRT) decision in breast cancer (BC) patients with pathologic negative lymph nodes (pN0) after modified radical mastectomy (MRM).

METHODS AND MATERIALS

A total of 699 BC patients with pN0 status after MRM, treated between 2001 and 2008, were identified from a prospective database in a single institution. Tumors were classified by intrinsic molecular subtype as luminal A or B, HER2+, and triple-negative (TN) using estrogen, progesterone, and HER2 receptors. Multivariate Cox analysis was used to determine the risk of LRR associated with intrinsic subtypes and Ki67 expression, adjusting for known prognostic factors.

RESULTS

At a median follow-up of 56 months, 17 patients developed LRR. Five-year LRR-free survival and overall survival in the entire population were 97%, and 94.7%, respectively, with no difference between the PMRT (n=191) and no-PMRT (n=508) subgroups. No constructed subtype was associated with an increased risk of LRR. Ki67 >20% was the only independent prognostic factor associated with increased LRR (hazard ratio, 4.18; 95% CI, 1.11-15.77; P<.0215). However, PMRT was not associated with better locoregional control in patients with proliferative tumors.

CONCLUSIONS

Ki67 expression but not molecular subtypes are predictors of locoregional recurrence in breast cancer patients with negative lymph nodes after MRM. The benefit of adjuvant RT in patients with proliferative tumors should be further investigated in prospective studies.

Aurora kinase A outperforms Ki67 as a prognostic marker in ER-positive breast cancer

Background:

Proliferation has emerged as a major prognostic factor in luminal breast cancer. The immunohistochemical (IHC) proliferation marker Ki67 has been most extensively investigated but has not gained widespread clinical acceptance.

Methods:

We have conducted a head-to-head comparison of a panel of proliferation markers, including Ki67. Our aim was to establish the marker of the greatest prognostic utility. Tumour samples from 3093 women with breast cancer were constructed as tissue microarrays. We used IHC to detect expression of mini-chromosome maintenance protein 2, Ki67, aurora kinase A (AURKA), polo-like kinase 1, geminin and phospho-histone H3. We used a Cox proportional-hazards model to investigate the association with 10-year breast cancer-specific survival (BCSS). Missing values were resolved using multiple imputation.

Results:

The prognostic significance of proliferation was limited to oestrogen receptor (ER)-positive breast cancer. Aurora kinase A emerged as the marker of the greatest prognostic significance in a multivariate model adjusted for the standard clinical and molecular covariates (hazard ratio 1.3; 95% confidence interval 1.1–1.5; P=0.005), outperforming all other markers including Ki67.

Conclusion:

Aurora kinase A outperforms other proliferation markers as an independent predictor of BCSS in ER-positive breast cancer. It has the potential for use in routine clinical practice.

Respective prognostic value of genomic grade and histological proliferation markers in early stage (pN0) breast carcinoma

BACKGROUND

Genomic grade (GG) is a 97-gene signature which improves the accuracy and prognostic value of histological grade (HG) in invasive breast carcinoma. Since most of the genes included in the GG are involved in cell proliferation, we performed a retrospective study to compare the prognostic value of GG, Mitotic Index and Ki67 score.

METHODS

A series of 163 consecutive breast cancers was retained (pT1-2, pN0, pM0, 10-yr follow-up). GG was computed using MapQuant Dx(R).

RESULTS

GG was low (GG-1) in 48%, high (GG-3) in 31% and equivocal in 21% of cases. For HG-2 tumors, 50% were classified as GG-1, 18% as GG-3 whereas 31% remained equivocal. In a subgroup of 132 ER+/HER2- tumors GG was the most significant prognostic factor in multivariate Cox regression analysis adjusted for age and tumor size (HR = 5.23, p = 0.02).

CONCLUSIONS

In a reference comprehensive cancer center setting, compared to histological grade, GG added significant information on cell proliferation in breast cancers. In patients with HG-2 carcinoma, applying the GG to guide the treatment scheme could lead to a reduction in adjuvant therapy prescription. However, based on the results observed and considering (i) the relatively close prognostic values of GG and Ki67, (ii) the reclassification of about 30% of HG-2 tumors as Equivocal GG and (iii) the economical and technical requirements of the MapQuant micro-array GG test, the availability in the near future of a PCR-based Genomic Grade test with improved performances may lead to an introduction in clinical routine of this test for histological grade 2, ER positive, HER2 negative breast carcinoma.

Significance of histomorphology of early triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous disease. Possibly genetic characterisation provides the most appropriate information on tumour biology and prognosis, but it is only limitedly available in clinical practice. The aim of this investigation was to explore what additional prognostic information could be gained from detailed histomorphologic report.

PATIENTS AND METHOD

patients were selected retrospectively operated from 2005 to 2009 in one institution and charts were revised. Beyond age, tumour and nodal status, histologic grade and therapy, the additional pathologic characteristics were also involved in analysis: necrosis, lymphocytic infiltration, peritumoural vascular invasion (PVI), perineural invasion, DCIS extent and grade, perinodal spread, mitotic activity index (MAI).

RESULTS

295 early TNBC were involved. In univariate survival analysis with a mean follow-up of 3.57 years the tumour size, the nodal status, type of operation (conservation or mastectomy), irradiation, PVI and perinodal spread proved to be significantly connected with both disease free survival (DFS) and breast cancer specific overall survival (BSOS), and necrosis and chemotherapy with BSOS. Necrosis analysed together with lymphocytic infiltrate showed greater predicting power. In multivariate analysis nodal metastasis, necrosis positive/lymphacytic infiltration negative status and lack of irradiation has significant negative impact on DFS (p = <0.0001 HR:1.98 [1.4-2.77], p = <0.017 HR:2.1 [1.1-3.8], p = <0.001 HR:0.25 [0.11-0.57], respectively) and BSOS (p = <0.0001 HR:2.47 [1.8-3.4], p = <0.017 HR:3.7 [1.6-8.2], p = <0.0017 HR:0.24 [0.1-0.58], respectively). For DFS perivascular invasion also showed significant effect (p = <0.042 HR:2.5 [1.0-6.0]). Nodal status was the strongest prognostic parameter but other histomorphologic parameters can be used for prognosis prediction.

Small-molecule targeting of proliferating cell nuclear antigen chromatin association inhibits tumor cell growth

Proliferating cell nuclear antigen (PCNA), a potential anticancer target, forms a homotrimer and is required for DNA replication and numerous other cellular processes. The purpose of this study was to identify novel small molecules that modulate PCNA activity to affect tumor cell proliferation. An in silico screen of a compound library against a crystal structure of PCNA and a subsequent structural similarity search of the ZINC chemical database were carried out to derive relevant docking partners. Nine compounds, termed PCNA inhibitors (PCNA-Is), were selected for further characterization. PCNA-I1 selectively bound to PCNA trimers with a dissociation constant (K(d)) of ~0.2 to 0.4 μM. PCNA-Is promoted the formation of SDS-refractory PCNA trimers. PCNA-I1 dose- and time-dependently reduced the chromatin-associated PCNA in cells. Consistent with its effects on PCNA trimer stabilization, PCNA-I1 inhibited the growth of tumor cells of various tissue types with an IC(50) of ~0.2 μM, whereas it affected the growth of nontransformed cells at significantly higher concentrations (IC(50), ~1.6 μM). Moreover, uptake of BrdU was dose-dependently reduced in cells treated with PCNA-I1. Mechanistically the PCNA-Is mimicked the effect of PCNA knockdown by siRNA, inducing cancer cell arrest at both the S and G(2)/M phases. Thus, we have identified a class of compounds that can directly bind to PCNA, stabilize PCNA trimers, reduce PCNA association with chromatin, and inhibit tumor cell growth by inducing a cell cycle arrest. They are valuable tools in studying PCNA function and may be useful for future PCNA-targeted cancer therapy.

Proteomics of mouse BRCA1-deficient mammary tumors identifies DNA repair proteins with potential diagnostic and prognostic value in human breast cancer

Breast cancer 1, early onset (BRCA1) hereditary breast cancer, a type of cancer with defects in the homology-directed DNA repair pathway, would benefit from the identification of proteins for diagnosis, which might also be of potential use as screening, prognostic, or predictive markers. Sporadic breast cancers with defects in the BRCA1 pathway might also be diagnosed. We employed proteomics based on one-dimensional gel electrophoresis in combination with nano-LC-MS/MS and spectral counting to compare the protein profiles of mammary tumor tissues of genetic mouse models either deficient or proficient in BRCA1. We identified a total of 3,545 proteins, of which 801 were significantly differentially regulated between the BRCA1-deficient and -proficient breast tumors. Pathway and protein complex analysis identified DNA repair and related functions as the major processes associated with the up-regulated proteins in the BRCA1-deficient tumors. In addition, by selecting highly connected nodes, we identified a BRCA1 deficiency signature of 45 proteins that enriches for homology-directed DNA repair deficiency in human gene expression breast cancer data sets. This signature also exhibits prognostic power across multiple data sets, with optimal performance in a data set enriched in tumors deficient in homology-directed DNA repair. In conclusion, by comparing mouse proteomes from BRCA1-proficient and -deficient mammary tumors, we were able to identify several markers associated with BRCA1 deficiency and a prognostic signature for human breast cancer deficient in homology-directed DNA repair.

Development of radiotracers for oncology--the interface with pharmacology

There is an increasing role for positron emission tomography (PET) in oncology, particularly as a component of early phase clinical trials. As a non-invasive functional imaging modality, PET can be used to assess both pharmacokinetics and pharmacodynamics of novel therapeutics by utilizing radiolabelled compounds. These studies can provide crucial information early in the drug development process that may influence the further development of novel therapeutics. PET imaging probes can also be used as early biomarkers of clinical response and to predict clinical outcome prior to the administration of therapeutic agents. We discuss the role of PET imaging particularly as applied to phase 0 studies and discuss the regulations involved in the development and synthesis of novel radioligands. The review also discusses currently available tracers and their role in the assessment of pharmacokinetics and pharmacodynamics as applied to oncology.

Anti-proliferative effects of the novel ceramide analog (S)-2-(benzylideneamino)-3-hydroxy-N-tetrade-cylpropanamide in chemoresistant cancer

The ceramide-sphingosine-1-phosphate rheostat is a promising therapeutic target. Here, the novel ceramide analog (S)-2-(benzylideneamino)-3-hydroxy-N-tetrade-cylpropanamide is shown to block proliferation and enhance the efficacy of the clinical chemotherapeutics, etoposide and doxorubicin. These results demonstrate the therapeutic potential of this compound in treating both endocrine resistant and chemoresistant breast cancer.

Comparison of visual and automated assessment of Ki-67 proliferative activity and their impact on outcome in primary operable invasive ductal breast cancer

Background:

Immunohistochemistry of Ki-67 protein is widely used to assess tumour proliferation, and is an established prognostic factor in breast cancer. There is interest in automating the assessment of Ki-67 labelling index (LI) with possible benefits in handling increased workload, with improved accuracy and precision.

Patients and methods:

Visual and automated assessment of Ki-67 LI and survival were examined in patients with primary operable invasive ductal breast cancer. Tissue microarrays (n=379 patients) immunostained for Ki-67 were scored visually and automatically with the Slidepath Tissue IA system.

Results:

Visual and automated Ki-67 LI were in excellent agreement (ICCC=0.96, P<0.001). On univariate analysis, visual (P<0.001) and automated Ki67 LI (P<0.05) were associated with cancer-specific survival in patients with invasive ductal breast cancer overall and in patients who received endocrine therapy (Tamoxifen) (P<0.01 for visual and P<0.05 for automated scoring).

Conclusion:

Automated assessment of Ki-67 LI would appear to be comparable to visual Ki-67 LI. However, automated Ki-67 LI assessment was inferior in predicting cancer survival in patients with breast cancer, including patients who received Tamoxifen.

Ki67, chemotherapy response, and prognosis in breast cancer patients receiving neoadjuvant treatment

Background

The pathological complete response (pCR) after neoadjuvant chemotherapy is a surrogate marker for a favorable prognosis in breast cancer patients. Factors capable of predicting a pCR, such as the proliferation marker Ki67, may therefore help improve our understanding of the drug response and its effect on the prognosis. This study investigated the predictive and prognostic value of Ki67 in patients with invasive breast cancer receiving neoadjuvant treatment for breast cancer.

Methods

Ki67 was stained routinely from core biopsies in 552 patients directly after the fixation and embedding process. HER2/neu, estrogen and progesterone receptors, and grading were also assessed before treatment. These data were used to construct univariate and multivariate models for predicting pCR and prognosis. The tumors were also classified by molecular phenotype to identify subgroups in which predicting pCR and prognosis with Ki67 might be feasible.

Results

Using a cut-off value of > 13% positively stained cancer cells, Ki67 was found to be an independent predictor for pCR (OR 3.5; 95% CI, 1.4, 10.1) and for overall survival (HR 8.1; 95% CI, 3.3 to 20.4) and distant disease-free survival (HR 3.2; 95% CI, 1.8 to 5.9). The mean Ki67 value was 50.6 ± 23.4% in patients with pCR. Patients without a pCR had an average of 26.7 ± 22.9% positively stained cancer cells.

Conclusions

Ki67 has predictive and prognostic value and is a feasible marker for clinical practice. It independently improved the prediction of treatment response and prognosis in a group of breast cancer patients receiving neoadjuvant treatment. As mean Ki67 values in patients with a pCR were very high, cut-off values in a high range above which the prognosis may be better than in patients with lower Ki67 values may be hypothesized. Larger studies will be needed in order to investigate these findings further.

Ki-67: level of evidence and methodological considerations for its role in the clinical management of breast cancer: analytical and critical review

Clinicians can use biomarkers to guide therapeutic decisions in estrogen receptor positive (ER+) breast cancer. One such biomarker is cellular proliferation as evaluated by Ki-67. This biomarker has been extensively studied and is easily assayed by histopathologists but it is not currently accepted as a standard. This review focuses on its prognostic and predictive value, and on methodological considerations for its measurement and the cut-points used for treatment decision. Data describing study design, patients’ characteristics, methods used and results were extracted from papers published between January 1990 and July 2010. In addition, the studies were assessed using the REMARK tool. Ki-67 is an independent prognostic factor for disease-free survival (HR 1.05–1.72) in multivariate analyses studies using samples from randomized clinical trials with secondary central analysis of the biomarker. The level of evidence (LOE) was judged to be I-B with the recently revised definition of Simon. However, standardization of the techniques and scoring methods are needed for the integration of this biomarker in everyday practice. Ki-67 was not found to be predictive for long-term follow-up after chemotherapy. Nevertheless, high KI-67 was found to be associated with immediate pathological complete response in the neoadjuvant setting, with an LOE of II-B. The REMARK score improved over time (with a range of 6–13/20 vs. 10–18/20, before and after 2005, respectively). KI-67 could be considered as a prognostic biomarker for therapeutic decision. It is assessed with a simple assay that could be standardized. However, international guidelines are needed for routine clinical use.

Protein expression, survival and docetaxel benefit in node-positive breast cancer treated with adjuvant chemotherapy in the FNCLCC-PACS 01 randomized trial

INTRODUCTION

The PACS01 trial has demonstrated that a docetaxel addition to adjuvant anthracycline-based chemotherapy improves disease-free survival (DFS) and overall survival of node-positive early breast cancer (EBC). We searched for prognostic and predictive markers for docetaxel's benefit.

METHODS

Tumor samples from 1,099 recruited women were analyzed for the expression of 34 selected proteins using immunohistochemistry. The prognostic and predictive values of each marker and four molecular subtypes (luminal A, luminal B, HER2-overexpressing, and triple-negative) were tested.

RESULTS

Progesterone receptor-negativity (HR = 0.66; 95% CI 0.47 to 0.92, P = 0.013), and Ki67-positivity (HR = 1.53; 95% CI 1.12 to 2.08, P = 0.007) were independent adverse prognostic factors. Out of the 34 proteins, only Ki67-positivity was associated with DFS improvement with docetaxel addition (adjusted HR = 0.51, 95% CI 0.33 to 0.79 for Ki67-positive versus HR = 1.10, 95% CI 0.75 to 1.61 for Ki67-negative tumors, P for interaction = 0.012). Molecular subtyping predicted the docetaxel benefit, but without providing additional information to Ki67 status. The luminal A subtype did not benefit from docetaxel (HR = 1.16, 95% CI 0.73 to 1.84); the reduction in the relapse risk was 53% (HR = 0.47, 95% CI 0.22 to 1.01), 34% (HR = 0.66, 95% CI 0.37 to 1.19), and 12% (HR = 0.88, 95% CI 0.49 to 1.57) in the luminal B, HER2-overexpressing, and triple-negative subtypes, respectively.

CONCLUSIONS

In patients with node-positive EBC receiving adjuvant anthracycline-based chemotherapy, the most powerful predictor of docetaxel benefit is Ki67-positivity.

Proliferating cell nuclear antigen is a novel inhibitory ligand for the natural cytotoxicity receptor NKp44

NK cells play an important role in the early immune response to cancer. The NKp44 activating receptor is the only natural cytotoxicity receptor that is expressed exclusively by primate NK cells, yet its cellular ligands remain largely unknown. Proliferating cell nuclear Ag (PCNA) is overexpressed in cancer cells. In this study, we show that the NKp44 receptor recognizes PCNA. Their interaction inhibits NK cell function through NKp44/ITIM. The physical interaction of NKp44 and PCNA is enabled by recruitment of target cell PCNA to the NK immunological synapse. We demonstrate that PCNA promotes cancer survival by immune evasion through inhibition of NKp44-mediated NK cell attack.

Assessment of Ki67 in breast cancer: recommendations from the International Ki67 in Breast Cancer working group

Uncontrolled proliferation is a hallmark of cancer. In breast cancer, immunohistochemical assessment of the proportion of cells staining for the nuclear antigen Ki67 has become the most widely used method for comparing proliferation between tumor samples. Potential uses include prognosis, prediction of relative responsiveness or resistance to chemotherapy or endocrine therapy, estimation of residual risk in patients on standard therapy and as a dynamic biomarker of treatment efficacy in samples taken before, during, and after neoadjuvant therapy, particularly neoadjuvant endocrine therapy. Increasingly, Ki67 is measured in these scenarios for clinical research, including as a primary efficacy endpoint for clinical trials, and sometimes for clinical management. At present, the enormous variation in analytical practice markedly limits the value of Ki67 in each of these contexts. On March 12, 2010, an international panel of investigators with substantial expertise in the assessment of Ki67 and in the development of biomarker guidelines was convened in London by the co-chairs of the Breast International Group and North American Breast Cancer Group Biomarker Working Party to consider evidence for potential applications. Comprehensive recommendations on preanalytical and analytical assessment, and interpretation and scoring of Ki67 were formulated based on current evidence. These recommendations are geared toward achieving a harmonized methodology, create greater between-laboratory and between-study comparability, and allow earlier valid applications of this marker in clinical practice.

Breast cancer biological subtypes and protein expression predict for the preferential distant metastasis sites: a nationwide cohort study

Introduction

Some molecular subtypes of breast cancer have preferential sites of distant relapse. The protein expression pattern of the primary tumor may influence the first distant metastasis site.

Methods

We identified from the files of the Finnish Cancer Registry patients diagnosed with breast cancer in five geographical regions Finland in 1991-1992, reviewed the hospital case records, and collected primary tumor tissue. Out of the 2,032 cases identified, 234 developed distant metastases after a median follow-up time of 2.7 years and had the first metastatic site documented (a total of 321 sites). Primary tumor microarray (TMA) cores were analyzed for 17 proteins using immunohistochemistry and for erbB2 using chromogenic in situ hybridization, and their associations with the first metastasis site were examined. The cancers were classified into luminal A, luminal B, HER2+ enriched, basal-like or non-expressor subtypes.

Results

A total of 3,886 TMA cores were analyzed. Luminal A cancers had a propensity to give rise first to bone metastases, HER2-enriched cancers to liver and lung metastases, and basal type cancers to liver and brain metastases. Primary tumors that gave first rise to bone metastases expressed frequently estrogen receptor (ER) and SNAI1 (SNAIL) and rarely COX2 and HER2, tumors with first metastases in the liver expressed infrequently SNAI1, those with lung metastases expressed frequently the epidermal growth factor receptor (EGFR), cytokeratin-5 (CK5) and HER2, and infrequently progesterone receptor (PgR), tumors with early skin metastases expressed infrequently E-cadherin, and breast tumors with first metastases in the brain expressed nestin, prominin-1 and CK5 and infrequently ER and PgR.

Conclusions

Breast tumor biological subtypes have a tendency to give rise to first distant metastases at certain body sites. Several primary tumor proteins were associated with homing of breast cancer cells.

Recurrence risk score based on the specific activity of CDK1 and CDK2 predicts response to neoadjuvant paclitaxel followed by 5-fluorouracil, epirubicin and cyclophosphamide in breast cancers

BACKGROUND

We established the cell cycle profiling (C2P) assay for specific activity (SA; activity/expression) of cyclin-dependent kinases (CDKs). C2P risk score (C2P-RS) based on CDK1 and CDK2 SAs was significantly associated with relapse in breast cancer (BC). This study was conducted to investigate the predictive value of C2P-RS for neoadjuvant chemotherapy (NAC).

PATIENTS AND METHODS

Among 124 eligible patients, 122 were treated with weekly paclitaxel followed by 5-fluorouracil, epirubicin and cyclophosphamide (P-FEC) and 2 were treated with paclitaxel monotherapy. C2P-RS was determined via C2P using frozen biopsy samples before NAC.

RESULTS

Negative estrogen receptor (ER), negative progesterone receptor (PR), positive human epidermal growth factor receptor 2 (HER2), high Ki-67 expression and intermediate + high C2P-RS were significantly associated with high pathological complete response (pCR) rates compared with positive ER (30% versus 9%), positive PR (25% versus 6%), negative HER2 (34% versus 11%), low Ki-67 expression (24% versus 7%) or low C2P-RS (24% versus 9%), respectively. The combination of C2P-RS and Ki-67 had a stronger impact on pCR than each parameter alone, and a multivariate analysis showed that the combination was an independent predictor of pCR (odds ratio 3.3, 95% confidence interval 1.1-9.5).

CONCLUSIONS

C2P-RS was significantly associated with pCR after P-FEC and may be a useful predictor for chemotherapy in BCs.

Breast cancers presenting luminal B subtype features show higher discordant human epidermal growth factor receptor 2 results between immunohistochemistry and fluorescence in situ hybridization

BACKGROUND

The aims of this study were to compare human epidermal growth factor receptor 2 (HER2) results between immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), and to investigate the clinicopathological characteristics and outcomes according to their results.

METHODS

Using consecutive tissue microarrays, IHC and FISH were performed as guidelines in 950 invasive breast cancers treated between November 1999 and August 2005. Characteristics and outcomes were retrospectively analyzed using a chi-square test, the Kaplan-Meier method, and Cox's model.

RESULTS

FISH-positivity was observed in 2.6%, 4.8%, 28.1%, and 93.8% of IHC 0, 1+, 2+, and 3+, respectively, and the concordance rate between the 2 assays was 95.5%. IHC-positive or FISH-positive cases were associated with poorer differentiation, negative expression of hormone receptors, and higher proliferative index. Among IHC-equivocal or IHC-negative patients, positive FISH was negatively associated with survival in univariate and multivariate analyses. Among IHC-negative patients, tumors showing luminal B subtype features such as estrogen receptor (ER)-positive, grade II/III, and high Ki-67 presented discordantly high FISH-positivity. Among IHC-positive cases, FISH was not related to outcomes.

CONCLUSIONS

The result of FISH is significantly related to prognosis of patients with IHC-negative or IHC-equivocal result. Therefore, FISH should be performed in IHC-equivocal cases. FISH assay might be considered for a selected group of patients with IHC-negative tumors showing luminal B subtype features of ER-positive, grade II/III, and high Ki-67 expression.

Prediction of outcome of early ER+ breast cancer is improved using a biomarker panel, which includes Ki-67 and p53

BACKGROUND

The aim of this study is to determine whether immunohistochemical (IHC) assessment of Ki67 and p53 improves prognostication of oestrogen receptor-positive (ER+) breast cancer after breast-conserving therapy (BCT). In all, 498 patients with invasive breast cancer from a randomised trial of BCT with or without tumour bed radiation boost were assessed using IHC.

METHODS

The ER+ tumours were classified as 'luminal A' (LA): ER+ and/or PR+, Ki-67 low, p53-, HER2- or 'luminal B' (LB): ER+ and/or PR+and/or Ki-67 high and/or p53+ and/or HER2+. Kaplan-Meier and Cox proportional hazards methodology were used to ascertain relationships to ispilateral breast tumour recurrence (IBTR), locoregional recurrence (LRR), distant metastasis-free survival (DMFS) and breast cancer-specific survival (BCSS).

RESULTS

In all, 73 patients previously LA were re-classified as LB: a greater than four-fold increase (4.6-19.3%) compared with ER, PR, HER2 alone. In multivariate analysis, the LB signature independently predicted LRR (hazard ratio (HR) 3.612, 95% CI 1.555-8.340, P=0.003), DMFS (HR 3.023, 95% CI 1.501-6.087, P=0.002) and BCSS (HR 3.617, 95% CI 1.629-8.031, P=0.002) but not IBTR.

CONCLUSION

The prognostic evaluation of ER+ breast cancer is improved using a marker panel, which includes Ki-67 and p53. This may help better define a group of poor prognosis ER+ patients with a greater probability of failure with endocrine therapy.

Proliferative activity in human breast cancer: Ki-67 automated evaluation and the influence of different Ki-67 equivalent antibodies

Background

Ki67 labeling index (Ki67 LI), the percentage Ki67 immunoreactive cells, is a measure of tumor proliferation, with important clinical relevance in breast cancer, and it is extremely important to standardize its evaluation.

Aim

To test the efficacy of computer assisted image analysis (CAIA) applied to completely digitized slides and to assess its feasibility in routine practice and compare the results obtained using two different Ki67 monoclonal antibodies.

Materials and methods

315 consecutive breast cancer routinely immunostained for Ki-67 (223 with SP6 and 92 with MM1 antibodies previously examined by an experienced pathologist, have been re-evaluated using Aperio Scanscope Xs.

Results

Mean human Ki67 LI values were 36%± 14.% and 28% ± 18% respectively for SP6 and MM1 antibodies; mean CAM Ki67 LI values were 31%± 19% and 22% ± 18% respectively for SP6 and MM1. Human and CAIA evaluation are statistically highly correlated (Pearson: 0.859, p<0.0001), although human LI are systematically higher. An interobserver variation study on CAIA performed on 84 cases showed that the correlation between the two evaluations was linear to an excellent degree.

Discussion

Our study shows that a) CAIA can be easily adopted in routine practice, b) human and CAIA Ki67 LI are highly correlated, although human LI are systematically higher, c) Ki67 LI using different evaluation methods and different antibodies shows important differences in cut-off values.

Development and evaluation of a virtual microscopy application for automated assessment of Ki-67 expression in breast cancer

Background

The aim of the study was to develop a virtual microscopy enabled method for assessment of Ki-67 expression and to study the prognostic value of the automated analysis in a comprehensive series of patients with breast cancer.

Methods

Using a previously reported virtual microscopy platform and an open source image processing tool, ImageJ, a method for assessment of immunohistochemically (IHC) stained area and intensity was created. A tissue microarray (TMA) series of breast cancer specimens from 1931 patients was immunostained for Ki-67, digitized with a whole slide scanner and uploaded to an image web server. The extent of Ki-67 staining in the tumour specimens was assessed both visually and with the image analysis algorithm. The prognostic value of the computer vision assessment of Ki-67 was evaluated by comparison of distant disease-free survival in patients with low, moderate or high expression of the protein.

Results

1648 evaluable image files from 1334 patients were analysed in less than two hours. Visual and automated Ki-67 extent of staining assessments showed a percentage agreement of 87% and weighted kappa value of 0.57. The hazard ratio for distant recurrence for patients with a computer determined moderate Ki-67 extent of staining was 1.77 (95% CI 1.31-2.37) and for high extent 2.34 (95% CI 1.76-3.10), compared to patients with a low extent. In multivariate survival analyses, automated assessment of Ki-67 extent of staining was retained as a significant prognostic factor.

Conclusions

Running high-throughput automated IHC algorithms on a virtual microscopy platform is feasible. Comparison of visual and automated assessments of Ki-67 expression shows moderate agreement. In multivariate survival analysis, the automated assessment of Ki-67 extent of staining is a significant and independent predictor of outcome in breast cancer.

Phytohemagglutinin-induced mitotic index in blood lymphocytes: a potential biomarker for breast cancer risk

Background

Cell proliferation is associated with the pathogenesis of cancer because it provides opportunities for accumulating genetic mutations. However, biomarkers of cell proliferation in response to environmental stimuli have not been adequately explored for breast cancer risk.

Methods

In a case-control study of 200 breast cancer patients and 360 healthy controls, we investigated the association between phytohemagglutinin (PHA)-induced mitotic index in blood lymphocyte and breast cancer risk.

Results

Having high mitotic index (>3.19%) was associated with an increased risk of breast cancer, with adjusted odds ratios (95% confidence interval) of 1.54 (1.03–2.30) and 2.03 (1.18–3.57) for all women and post-menopausal women, respectively. Mitotic index was correlated with some reproductive factors and body mass index in controls.

Conclusions

Our data suggest increased PHA-induced mitotic index in blood lymphocytes is associated with an increased breast cancer risk and that this association may be modulated by reproductive and other hormones.

Histological grading of breast cancer on needle core biopsy: the role of immunohistochemical assessment of proliferation

Aims

Histological grade assessed on needle core biopsy (NCB) moderately concurs with the grade in the surgical excision specimen (SES) (κ-values between 0.35 and 0.65). A major cause of the discrepancy is underestimation of mitoses in the NCB specimen. The aim was to determine the best method of assessing proliferation on NCB.

Methods and results

Proliferative activity of 101 invasive carcinomas of the breast on NCB and SES was assessed using mitotic counts on routine haematoxylin and eosin (H&E) sections and immunohistochemical markers Mib-1 and phosphorylated histone H3 (PPH3). H&E mitotic count in SES was considered as the gold standard. H&E mitotic count was found to be underestimated on NCB when compared with that in SES (P < 0.001), but no significant difference was detected between NCB and SES regarding Mib-1 (P = 0.13) or PPH3 (P = 0.073). Using receiver–operating characteristic curve, Mib-1 on NCB was found to agree with the gold standard significantly better than routine H&E on NCB.

Conclusions

Immunohistochemical markers in NCB showed better concordance with H&E mitotic count in SES (gold standard) than routine H&E mitotic count in NCB. Further refinement of cut-offs and scoring methods is needed.

Enhanced expression of cyclins and cyclin-dependent kinases in aniline-induced cell proliferation in rat spleen

Aniline exposure is associated with toxicity to the spleen leading to splenomegaly, hyperplasia, fibrosis and a variety of sarcomas of the spleen on chronic exposure. In earlier studies, we have shown that aniline exposure leads to iron overload, oxidative stress and activation of redox-sensitive transcription factors, which could regulate various genes leading to a tumorigenic response in the spleen. However, molecular mechanisms leading to aniline-induced cellular proliferation in the spleen remain largely unknown. This study was, therefore, undertaken on the regulation of G1 phase cell cycle proteins (cyclins), expression of cyclin-dependent kinases (CDKs), phosphorylation of retinoblastoma protein (pRB) and cell proliferation in the spleen, in an experimental condition preceding a tumorigenic response. Male SD rats were treated with aniline (0.5 mmol/kg/day via drinking water) for 30 days (controls received drinking water only), and splenocyte proliferation, protein expression of G1 phase cyclins, CDKs and pRB were measured. Aniline treatment resulted in significant increases in splenocyte proliferation, based on cell counts, cell proliferation markers including proliferating cell nuclear antigen (PCNA), nuclear Ki67 protein (Ki67) and minichromosome maintenance (MCM), MTT assay and flow cytometric analysis. Western blot analysis of splenocyte proteins from aniline-treated rats showed significantly increased expression of cyclins D1, D2, D3 and E, as compared to the controls. Similarly, real-time PCR analysis showed significantly increased mRNA expression for cyclins D1, D2, D3 and E in the spleens of aniline-treated rats. The overexpression of these cyclins was associated with increases in the expression of CDK4, CDK6, CDK2 as well as phosphorylation of pRB protein. Our data suggest that increased expression of cyclins, CDKs and phosphorylation of pRB protein could be critical in cell proliferation, and may contribute to aniline-induced tumorigenic response in the spleen.

Antiestrogenic effects of the novel sphingosine kinase-2 inhibitor ABC294640

Alterations in sphingolipid metabolism have been shown to contribute to the development of endocrine resistance and breast cancer tumor survival. Sphingosine kinase (SK), in particular, is overexpressed in breast cancer and is a promising target for breast cancer drug development. In this study, we used the novel SK inhibitor ABC294640 as a tool to explore the relationship between SK and estrogen (E2) receptor (ER) signaling in breast cancer cells. Treatment with ABC294640 decreased E2-stimulated ERE-luciferase activity in both MCF-7 and ER-transfected HEK293 cells. Furthermore, the inhibitor reduced E2-mediated transcription of the ER-regulated genes progesterone receptor and SDF-1. Competitive receptor-binding assays revealed that ABC294640 binds in the antagonist ligand-binding domain of the ER, acting as a partial antagonist similar to tamoxifen. Finally, treatment with ABC294640 inhibited ER-positive breast cancer tumor formation in vivo. After 15 d of treatment with ABC294640, tumor volume was reduced by 68.4% (P < 0.05; n = 5) compared with control tumors, with no marked weight loss or illness. Taken together, these results provide strong evidence that this novel SK inhibitor, which had not previously been known to interact with E2 signaling pathways, has therapeutic potential in treating ER-positive breast cancer via inhibition of both SK and ER signaling.

Breast cancer assessment tools and optimizing adjuvant therapy

Recommendation of systemic adjuvant therapy and choice of optimal agents for early-stage breast cancer remains a challenge. Adjuvant therapy is indicated on the assumption of residual micrometastatic disease. Adjuvant assessment tools for prognosis and prediction of treatment benefit, including Adjuvant! Online, the St Gallen Consensus, Oncotype DX(®) and MammaPrint(®), aid clinical decision making. However, all of these tools have limitations that must be considered in their judicious application. Clinicopathological based tools are critically dependent on accurate, standardized measurement of parameters. Multigene tools are appealing for their objectivity and reproducibility, particularly regarding analysis of proliferation, but these approaches still overlook the biological heterogeneity within tumors evidenced by distinct cell subpopulations with different genomic patterns and function. The greatest treatment challenge remains for patients assessed as intermediate risk of relapse, a problem not overcome by multigene tools. Remarkable diversity in breast cancer dictates that adjuvant management must be biologically driven. Future identification of predictive biomarkers for specific chemotherapy sensitivity may allow targeted use of available agents, including anthracyclines, taxanes and DNA damaging agents. The presence of drug targets and targetable signaling pathways, rather than molecularly defined subgroups, may ultimately drive treatment decisions.

Prognostic and therapeutic implications of distinct kinase expression patterns in different subtypes of breast cancer

Different kinases are expressed in different clinical subsets of breast cancer. In this study, we assessed kinase expression patterns in different clinical subtypes of breast cancer, evaluated the prognostic and predictive values of kinase metagenes, and investigated their functions in vitro. Four hundred twenty-eight protein kinases in gene expression data were examined from 684 cases of breast cancer and 51 breast cancer cell lines to identify kinase expression patterns. We tested the prognostic value of kinase metagenes in 684 node-negative patients who received no adjuvant therapy and the predictive value in 233 patients who received uniform neoadjuvant chemotherapy. Twelve kinases were overexpressed in estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative, 7 in HER2(+), and 28 in ER(-)/HER2(-) cancers, respectively. We examined the functional role of 22 kinases overexpressed in ER(-)/HER2(-) cancers using siRNA. Downregulation of these kinases caused significant subtype-specific inhibition of cell growth in vitro. Two robust kinase clusters, including an immune kinase cluster and a mitosis kinase cluster, were present in all clinical subgroups. High mitosis kinase score was associated with worse prognosis but higher pathologic complete response (pCR) in ER(+)/HER2(-) cancers, but not in ER(-)/HER2(-) or HER2(+) cancers, in univariate and multivariate analyses including other genomic predictors (MammaPrint, genomic grade index, and the 76-gene signature). Conversely, higher immune kinase score was associated with better survival in ER(+)/HER2(-) and HER2(+) tumors and also predicted higher probability of pCR in HER2(+) cancers. Taken together, our results indicate that kinases regulating mitosis and immune functions convey distinct prognostic information that varies by clinical subtype.

Evaluation of the bioconjugation efficiency of different quantum dots as probes for immunostaining tumor-marker proteins

The differing bioconjugation efficiencies of quantum dots (QDs) are a practical obstacle to their popularization. Differences in bioconjugation efficiency based on immunostaining the same targeted molecules using different batches of QDs need to be evaluated prior to their application. In this paper, a quantitative method for evaluating the efficiency of QDs in staining tissues has been developed based on Hadamard transform (HT) spectral imaging. Proliferating cell nuclear antigens (PCNA) in breast cancer tissues were labeled with bioconjugated QD bioprobes using a 454 nm laser as the light source for fluorescence spectral imaging. Four-dimensional (4D) spectral imaging analysis of PCNA in cell nuclei was carried out using HT spectral microscopy based on immunostaining with different batches of QDs. The fluorescence intensity distributions in the cell nuclei were collected from the 4D images. Based on the information obtained from microscopic spectra and 4D images, differences in the bioconjugation efficiency among different batches of QDs were evaluated. The results demonstrate that it is possible to maintain uniform bioconjugation efficiencies with different QD bioconjugation processes in order to obtain accurate and reliable results in biomedical analysis and cancer diagnosis.

ImmunoRatio: a publicly available web application for quantitative image analysis of estrogen receptor (ER), progesterone receptor (PR), and Ki-67

INTRODUCTION

Accurate assessment of estrogen receptor (ER), progesterone receptor (PR), and Ki-67 is essential in the histopathologic diagnostics of breast cancer. Commercially available image analysis systems are usually bundled with dedicated analysis hardware and, to our knowledge, no easily installable, free software for immunostained slide scoring has been described. In this study, we describe a free, Internet-based web application for quantitative image analysis of ER, PR, and Ki-67 immunohistochemistry in breast cancer tissue sections.

METHODS

The application, named ImmunoRatio, calculates the percentage of positively stained nuclear area (labeling index) by using a color deconvolution algorithm for separating the staining components (diaminobenzidine and hematoxylin) and adaptive thresholding for nuclear area segmentation. ImmunoRatio was calibrated using cell counts defined visually as the gold standard (training set, n = 50). Validation was done using a separate set of 50 ER, PR, and Ki-67 stained slides (test set, n = 50). In addition, Ki-67 labeling indexes determined by ImmunoRatio were studied for their prognostic value in a retrospective cohort of 123 breast cancer patients.

RESULTS

The labeling indexes by calibrated ImmunoRatio analyses correlated well with those defined visually in the test set (correlation coefficient r = 0.98). Using the median Ki-67 labeling index (20%) as a cutoff, a hazard ratio of 2.2 was obtained in the survival analysis (n = 123, P = 0.01). ImmunoRatio was shown to adapt to various staining protocols, microscope setups, digital camera models, and image acquisition settings. The application can be used directly with web browsers running on modern operating systems (e.g., Microsoft Windows, Linux distributions, and Mac OS). No software downloads or installations are required. ImmunoRatio is open source software, and the web application is publicly accessible on our website.

CONCLUSIONS

We anticipate that free web applications, such as ImmunoRatio, will make the quantitative image analysis of ER, PR, and Ki-67 easy and straightforward in the diagnostic assessment of breast cancer specimens.

Ki67 in breast cancer: prognostic and predictive potential

The leading parameters that define treatment recommendations in early breast cancer are oestrogen-receptor, progesterone-receptor, and human epidermal growth-factor status. Although some pathologists report Ki67 in addition to other biological markers, the existing guidelines of the American Society of Clinical Oncology do not include Ki67 in the list of required routine biological markers. The advent of new genetic tests has emphasised the role of proliferative genes, including Ki67, as prognostic and predictive markers. Additionally, randomised studies have retrospectively reviewed data and reported on the role of Ki67 in breast cancer. In light of new data, we have re-assessed evidence that could change guidelines to include Ki67 in the standard pathological assessment of early breast cancers. This review provides an update on the current knowledge on Ki67 and of the evidence in the published work about the prognostic and predictive role of this marker, and provides information on the laboratory techniques used to determine Ki67.

Histopathological prognostic factors in early breast carcinoma: an evaluation of cell proliferation in carcinoma cells

Early breast carcinoma is defined as pathological stage 1 (pT1N0M0) tumour and its incidence has recently increased possibly due to the advent of mammography based mass screening. Overall survival of these patients is in general excellent, but more than 20% of them will eventually develop distant metastasis and die. Therefore, an establishment of prognostic factors could contribute greatly to determining the algorithm for treating these patients after surgery. Histopathological prognostic factors still play pivotal roles in the management of these patients. Among these, Nottingham histological grade is considered the gold standard for determining the clinical outcome of early breast cancer patients if done in optimally processed tissue specimens by well-trained pathologists. Among these histological factors of Nottingham histological grade, mitotic index has been demonstrated to provide the most significant information as to prognosis of these patients. Attempts have been made to assess the status of tumour cell proliferation in practical, reproducible and accurate manners in the past. Among these attempts, immunohistochemical analysis of cell cycle associated nuclear antigens, especially Ki67/MIB1 labelling index in archival materials, has been reported to provide clinically inert and significant information. However, its methodologies, including processing of the specimens, and modes of interpretation should be standardised before this Ki67/MIB1 labelling index can become incorporated into routine clinical practice in the management of early breast carcinoma patients.

Securin promotes the identification of favourable outcome in invasive breast cancer

Background:

Securin is a recently recognised oncogene with multiple known functions in initiation, progression and cell cycle regulation in several malignant diseases, including breast carcinoma.

Methods:

In this paper, the prognostic value of securin is evaluated by immunohistochemistry in 310 patients diagnosed with invasive breast cancer during a mammographic screening programme in Central Finland. All patients were directed to modern surgical and oncological treatments and were followed up for a maximum of 20 years.

Results:

Our results suggest that securin immunopositivity is an independent prognosticator of invasive breast cancer. In our study, securin predicted breast cancer-specific survival among all cases of invasive breast cancer and subgroups divided according to histological type, Ki-67 proliferation status and tumour size. Especially in a multivariate analysis standardised for axillary lymph node status, patient's age and tumour size at the time of diagnosis, securin immunopositivity indicated a 13.1-fold risk of breast cancer death (P=0.024) among invasive ductal breast carcinomas with low Ki-67 positivity.

Conclusion:

Our present and previous results suggest that securin could be useful in clinical pathology to intensify the power of the established prognosticators of invasive breast cancer and, especially, to assist in identifying patients with a more favourable outcome than that indicated by Ki-67 alone.

Validation of UBE2C protein as a prognostic marker in node-positive breast cancer

Background:

We recently identified and validated UBE2C RNA as a prognostic marker in 252 node-positive (N+) breast cancers by means of a microarray study. The aim of this study was to validate UBE2C protein as a prognostic marker in N+ breast cancer by immunohistochemistry (IHC).

Methods:

To this end, 92 paraffin-embedded blocks were used. The impact of UBE2C IHC value on metastasis-free survival (MFS) and overall survival (OS) was evaluated and compared with Ki-67 and Nottingham prognostic index (NPI) performances.

Results:

In accordance with genomic data, UBE2C IHC had a significant impact both on MFS and OS (hazard ratio=6.79 – P=0.002; hazard ratio=7.14 – P=0.009, respectively). Akaike information criterion proved that the prognostic power of UBE2C IHC was stronger than that of Ki-67 (and close to that of NPI). Furthermore, multivariate analyses with NPI showed that, contrary to Ki-67 IHC, UBE2C IHC remained an independent factor, both for MFS (adjusted P=0.02) and OS (adjusted P=0.04).

Conclusion:

We confirmed that UBE2C protein measured by IHC could be used as a prognostic marker in N+ breast cancer. The potential predictive interest of UBE2C as a marker of proteasome activity needs further investigations.

Ki67 index, HER2 status, and prognosis of patients with luminal B breast cancer

Background

Gene expression profiling of breast cancer has identified two biologically distinct estrogen receptor (ER)-positive subtypes of breast cancer: luminal A and luminal B. Luminal B tumors have higher proliferation and poorer prognosis than luminal A tumors. In this study, we developed a clinically practical immunohistochemistry assay to distinguish luminal B from luminal A tumors and investigated its ability to separate tumors according to breast cancer recurrence-free and disease-specific survival.

Methods

Tumors from a cohort of 357 patients with invasive breast carcinomas were subtyped by gene expression profile. Hormone receptor status, HER2 status, and the Ki67 index (percentage of Ki67-positive cancer nuclei) were determined immunohistochemically. Receiver operating characteristic curves were used to determine the Ki67 cut point to distinguish luminal B from luminal A tumors. The prognostic value of the immunohistochemical assignment for breast cancer recurrence-free and disease-specific survival was investigated with an independent tissue microarray series of 4046 breast cancers by use of Kaplan–Meier curves and multivariable Cox regression.

Results

Gene expression profiling classified 101 (28%) of the 357 tumors as luminal A and 69 (19%) as luminal B. The best Ki67 index cut point to distinguish luminal B from luminal A tumors was 13.25%. In an independent cohort of 4046 patients with breast cancer, 2847 had hormone receptor–positive tumors. When HER2 immunohistochemistry and the Ki67 index were used to subtype these 2847 tumors, we classified 1530 (59%, 95% confidence interval [CI] = 57% to 61%) as luminal A, 846 (33%, 95% CI = 31% to 34%) as luminal B, and 222 (9%, 95% CI = 7% to 10%) as luminal–HER2 positive. Luminal B and luminal–HER2-positive breast cancers were statistically significantly associated with poor breast cancer recurrence-free and disease-specific survival in all adjuvant systemic treatment categories. Of particular relevance are women who received tamoxifen as their sole adjuvant systemic therapy, among whom the 10-year breast cancer–specific survival was 79% (95% CI = 76% to 83%) for luminal A, 64% (95% CI = 59% to 70%) for luminal B, and 57% (95% CI = 47% to 69%) for luminal–HER2 subtypes.

Conclusion

Expression of ER, progesterone receptor, and HER2 proteins and the Ki67 index appear to distinguish luminal A from luminal B breast cancer subtypes.