Molecular differences between younger versus older ER-positive and HER2-negative breast cancers.

The RxPONDER and TAILORx trials demonstrated benefit from adjuvant chemotherapy in patients age ≤ 50 with node-positive breast cancer and Recurrence Score (RS) 0-26, and in node-negative disease with RS 16-25, respectively, but no benefit in older women with the same clinical features. We analyzed transcriptomic and genomic data of ER+/HER2- breast cancers with in silico RS < 26 from TCGA (n = 530), two microarray cohorts (A: n = 865; B: n = 609), the METABRIC (n = 867), and the SCAN-B (n = 1636) datasets. There was no difference in proliferation-related gene expression between age groups. Older patients had higher mutation burden and more frequent ESR1 copy number gain, but lower frequency of GATA3 mutations. Younger patients had higher rate of ESR1 copy number loss. In all datasets, younger patients had significantly lower mRNA expression of ESR1 and ER-associated genes, and higher expression of immune-related genes. The ER- and immune-related gene signatures showed negative correlation and defined three subpopulations in younger women: immune-high/ER-low, immune-intermediate/ER-intermediate, and immune-low/ER-intermediate. We hypothesize that in immune-high cancers, the cytotoxic effect of chemotherapy may drive the benefit, whereas in immune-low/ER-intermediate cancers chemotherapy induced ovarian suppression may play important role.

A Small Hypoxia Signature Predicted pCR Response to Bevacizumab in the Neoadjuvant GeparQuinto Breast Cancer Trial.

PURPOSE: In breast cancer, bevacizumab increased pCR rate but not long-term survival and no predictive markers are available to identify patients with long-term benefit from the drug. EXPERIMENTAL DESIGN: We profiled 289 pretherapeutic formalin-fixed, paraffin-embedded (FFPE) biopsies of HER2-negative patients from the GeparQuinto trial of neoadjuvant chemotherapy ± bevacizumab by exome-capture RNA-sequencing (RNA-seq). In a prospectively planned study, we tested molecular signatures for response prediction. IHC validation was performed using tissue microarrays. RESULTS: We found strong agreement of molecular and pathologic parameters as hormone receptors, grading, and lymphocyte infiltration in 221 high-quality samples. Response rates (49.3% pCR overall) were higher in basal-like (68.9%) and HER2-enriched (45.5%) than in luminal B (35.7%), luminal A (17.9%), and normal-like (20.0%) subtypes. T-cell (OR = 1.60; 95% confidence interval, 1.21-2.12; P = 0.001), proliferation (OR = 2.88; 95% CI, 2.00-4.15; P < 0.001), and hypoxia signatures (OR = 1.92; 95% CI, 1.41-2.60; P < 0.001) significantly predicted pCR in univariate analysis. In a prespecified multivariate logistic regression, a small hypoxia signature predicted pCR (OR = 2.40; 95% CI, 1.28-4.51; P = 0.006) with a significant interaction with bevacizumab treatment (P = 0.020). IHC validation using NDRG1 as marker revealed highly heterogenous expression within tissue leading to profound loss of sensitivity in TMA analysis, still a significant predictive value for pCR was detected (P = 0.025). CONCLUSIONS: Exome-capture RNA-seq characterizes small FFPE core biopsies by reliably detecting factors as for example ER status, grade, and tumor-infiltrating lymphocytes levels. Beside molecular subtypes and immune signatures, a small hypoxia signature predicted pCR to bevacizumab, which could be validated by IHC. The signature can have important applications for bevacizumab treatment in different cancer types and might also have a role for novel combination therapies of bevacizumab with immune checkpoint inhibition.

Histotype-specific analysis of acid ceramidase expression in ovarian cancer.

Acid ceramidase (ASAH1) is a key player in sphingolipid metabolism and signaling. It has prognostic value for several cancers, but histotype-specific analyses of ovarian cancer are not yet available. We used three retrospective TMA cohorts encompassing a total of 1106 ovarian cancers with follow-up data for immunohistochemical analysis of acid ceramidase (ASAH1) expression. Patients with sub-optimal debulking and persistent residual tumor after surgery introduced bias in the prognostic analysis and were excluded from further studies. Overall, we detected an association of ASAH1 expression with better prognosis in ovarian cancer patients. ASAH1 expression differed between histological ovarian cancer histotypes with most frequent expression in endometrioid and clear cell ovarian cancer, which are both associated with good prognosis. Stratified subgroup analyses within these histotypes did not reveal significant survival differences, but the power of the analysis may be limited by smaller sample sizes. In contrast to breast cancer, we found only a modest concordance between estrogen receptor status and ASAH1 expression within the endometrioid ovarian cancer histotype. In an exploratory analysis of estrogen receptor negative endometrioid ovarian cancer, ASAH1 expression was associated with significantly better overall survival (P = 0.007). Acid ceramidase is most frequently expressed in endometrioid and clear cell histotypes and could add independent prognostic value to estrogen receptor in endometrioid ovarian cancer. Modulating sphingolipid metabolism may lead to novel therapeutic intervention strategies for this disease.

Claudin-1 is linked to presence of implants and micropapillary pattern in serous borderline epithelial tumours of the ovary.

AIMS: Expression of Claudin-1 has been associated with prognosis in several cancers. Here we investigated the expression pattern of Claudin-1 in borderline tumours of the ovary (BOT). METHODS: We analysed a cohort of 114 cases of borderline tumour (BOT). Claudin-1 expression was studied by immunohistochemistry using a polyclonal antibody and was compared with clinical and histopathological characteristics. RESULTS: Strong Claudin-1 expression was found in 30 cases (26.3%) independent of histological subtype. Expression was significantly less frequent in International Federation of Gynecology and Obstetrics (FIGO) stage I (p= 0.045), while the presence of microinvasion did not correlate with Claudin-1 expression. In contrast, we detected a highly significant association of Claudin-1 expression with the presence of peritoneal implants (p=0.003) and micropapillary pattern (p=0.047), which are features exclusively seen in serous BOT. Moreover, when we restricted our analysis to the subtype of serous BOT, the association of Claudin-1 expression with peritoneal implants (p<0.001) and micropapillary pattern (p =0.003) remained highly significant. CONCLUSIONS: In conclusion, Claudin-1 expression is associated with the presence of peritoneal implants and micropapillary pattern, which have been shown to be associated with poor prognosis. We speculate that overexpression of Claudin-1 might be linked to the mitogen-activated protein kinase pathway activation in BOT and suggest further studies to define its prognostic and potential therapeutic value.

Catheter-related Complications of Subcutaneous Implantable Venous Access Devices in Breast Cancer Patients.

BACKGROUND/AIM: Totally implanted venous access devices (TIVAD) are increasingly used in the treatment of cancer patients. The aim of this study was to assess the incidence of early and late complications resulting from subcutaneous TIVADs in patients with breast cancer. MATERIALS AND METHODS: Between 2004 and 2009, we reviewed patients with breast cancer who had a TIVAD placed. Early and late complications, as well as risk factors for TIVAD-associated thrombosis were retrospectively assessed. RESULTS: A total of 281 patients were included. Complications occurred in 26% of patients, the majority of which were late complications (21.4%.) The development of TIVAD associated thrombosis was the most frequent late complication (16.4%). In the univariate analysis followed by a multivariate model, risk factors for TIVAD associated thrombosis were not identified. Only within the subgroup of metastatic breast cancer patients an increased risk of TIVAD-associated thrombosis of left compared to right venous access was detected (p=0.015). CONCLUSION: TIVAD implantation done in a gynecological outpatient setting is feasible and safe.

TFF3 Expression as Stratification Marker in Borderline Epithelial Tumors of the Ovary.

Borderline tumors (BOT) of the ovary account for 10% to 20% of ovarian neoplasms. Like ovarian cancer, BOT encompass several different histological subtypes (serous, mucinous, endometrioid, clear cell, transitional cell and mixed) with serous (SBOT) and mucinous (MBOT) the most common. Current hypotheses suggest low-grade serous carcinoma may develop in a stepwise fashion from SBOT whereas the majority of high grade serous carcinomas develop rapidly presumably from inclusion cysts or ovarian surface epithelium. The pathogenesis of mucinous ovarian tumors is still puzzling. Molecular markers could help to better define relationships between such entities. Trefoil factor-3 (TFF3) is an estrogen-regulated gene associated with prognosis in different types of cancer. It has also been included in a recent marker panel predicting subtypes of ovarian carcinoma. We analyzed the expression of TFF3 by immunohistochemistry in a cohort of 137 BOT and its association with histopathological features. Overall expression rate of TFF3 was 21.9%. None of the BOT with serous and endometrioid histology displayed strong TFF3 expression. On the other hand, TFF3 was highly expressed in 61.4% of MBOT cases and 33.3% of BOT with mixed histology (P < 0.001) suggesting a potential function of the protein in that subtypes. Associations of TFF3 expression with FIGO stage and micropapillary pattern were significant in the overall cohort but confounded by their correlation with histological subtypes. The highly specific expression of TFF3 in MBOT may help to further clarify potential relationships of tumors with mucinous histology and warrants further studies.

Claudin-1 expression in cervical cancer.

Claudin-1 is a tight junction protein that has been demonstrated to be involved in tumorigenesis and tumor progression in various types of solid tumors. In the present study, the protein expression of claudin-1 in squamous cervical cancer tissues obtained from 106 patients was analyzed by immunohistochemistry. In addition, the grade of claudin-1 expression was analyzed for associations with certain clinicopathological parameters. A significant overexpression of claudin-1 was detected in the tumor cells, when compared with that in the peritumoral stroma. There was no significant association between claudin-1 expression and FIGO stage, tumor size, grading or the appearance of distant metastases. Cervical cancer patients scoring positive for claudin-1 protein expression tended to exhibit more lymph node metastasis (28.3%), compared with claudin-1-negative patients (7.1%). Regarding overall survival, the results of the present study suggest a better prognosis for claudin-1-negative patients. In order to elucidate whether claudin-1 overexpression has a significant prognostic impact on squamous cervical cancer, further studies are required.

Association Between Genomic Metrics and Immune Infiltration in Triple-Negative Breast Cancer.

Importance: Why some triple-negative breast cancers (TNBCs) have high and others have low immune cell infiltration is unknown. Understanding how immune surveillance shapes the cancer genome could help in the selection of patients and the development of more effective immunotherapy strategies. Objective: To examine the association between genomic metrics and the extent of immune infiltration in TNBCs. Design, Setting, and Participants: This study, performed from June 1, 2015, through January 31, 2017, used DNA and RNA sequencing data and messenger RNA expression results from The Cancer Genome Atlas (TCGA) breast cancer data set (n = 1215) to calculate previously described immune metagene expression values and histologic lymphocyte counts to quantify immune infiltration and assign prognostic categories to TNBCs. It used the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) data set as an independent validation cohort. The study compared clonal heterogeneity, somatic total mutational load, neoantigen load, and somatic copy number alteration levels between immune-rich TNBC cohorts with good prognosis and immune-poor TNBC cohorts with poor prognosis. The study also compared the distribution of mutations in 119 canonical cancer genes. Main Outcomes and Measures: Correlation between immune prognostic category and genomic metrics of the cancer. Results: This study of 193 TNBC samples with patient survival information found an inverse association between clonal heterogeneity and immune metagene expression (ρ = −0.395, P = 2 × 10−8). The study also found an inverse association between immune metagene expression and somatic copy number alteration levels (ρ = −0.484, P = 2 × 10−10). Lymphocyte-rich TNBCs with good prognosis had significantly lower mutation and neoantigen counts than did lymphocyte-poor TNBCs with poor prognosis. The robustness of the study results was confirmed by using various immune metagenes in the same TCGA data set and in the independent METABRIC data set. Conclusions and Relevance: This study suggests that immune-rich TNBCs may be under an immune surveillance that continuously eliminates many immunogenic clones, resulting in lower clonal heterogeneity. These cancers may also represent the subset of TNBCs that could derive benefit from immune checkpoint inhibitor therapy to tilt the balance in favor of the immune system.

IMP3 Expression in Borderline Tumors of the Ovary.

BACKGROUND/AIM: Borderline ovarian tumors (BOTs) have a less aggressive behavior than invasive epithelial ovarian tumors. Still some patients relapse or succumb to disease. Molecular markers that reliably predict prognosis are lacking. Insulin-like growth factor II mRNA-binding protein (IMP3) has been suggested as a prognostic marker in colorectal, hepatocellular, and ovarian clear-cell carcinomas. MATERIALS AND METHODS: We analyzed the expression of IMP3 by immunohistochemistry in a cohort of 140 BOT and its association with histopathological features. RESULTS: We found no association of IMP3 expression with patients' age, FIGO stage, microinvasion, and presence of implants. In contrast, IMP3 expression correlated to mucinous subtype of BOTs (42.2% vs. 9.5% among other subtypes) (p<0.001). IMP3 expression was found to be associated with the presence of in situ carcinoma in MBOT, but not in other subtypes (p=0.021). CONCLUSION: Expression of IMP3 in BOT is associated with the mucinous subtype and may serve as an early indicator for the development of malignant features.

Targeting of PYK2 Synergizes with EGFR Antagonists in Basal-like TNBC and Circumvents HER3-Associated Resistance via the NEDD4-NDRG1 Axis.

Triple-negative breast cancer (TNBC) is a highly aggressive, heterogeneous disease with poor prognosis and no effective targeted therapies. EGFR is highly expressed in basal-like TNBC and is considered as a potential therapeutic target. However, EGFR targeting exerts only marginal clinical benefits, possibly due to activation of compensatory signaling pathways, which are frequently associated with HER3 upregulation. Here we show that concomitant targeting of EGFR and the nonreceptor tyrosine kinases PYK2/FAK synergistically inhibits the proliferation of basal-like TNBC cells in vitro and attenuates tumor growth in a mouse xenograft model. Dual targeting of EGFR and PYK2/FAK inhibited complementary key growth and survival pathways mediated by AKT, S6K, STAT3, and ERK1/2 activation. PYK2 inhibition also abrogated HER3 upregulation in response to EGFR antagonists, thereby circumventing HER3-associated drug resistance. Mechanistically, PYK2 inhibition facilitated the proteasomal degradation of HER3 while inducing upregulation of NDRG1 (N-myc downstream regulated 1 gene). NDRG1 enhanced the interaction of HER3 with the ubiquitin ligase NEDD4, while PYK2, which interacts with NEDD4 and HER3, interfered with NEDD4-HER3 binding, suggesting that the PYK2-NDRG1-NEDD4 circuit has a critical role in receptor degradation, drug response, and resistance mechanism. Our studies offer a preclinical proof of concept for a strategy of cotargeting the EGFR and PYK2/FAK kinases to improve TNBC therapy. Cancer Res; 77(1); 86-99. ©2016 AACR.

Trefoil factor 3 expression in epithelial ovarian cancer exerts a minor effect on clinicopathological parameters.

The role of trefoil factor 3 (intestinal) (TFF3) has been analyzed in numerous cancers, such as breast and gastrointestinal cancer, and has been associated with poor prognosis. However, the role of TFF3 in ovarian cancers is not clear. Expression analysis of TFF3 in 91 ovarian cancer patients was performed by immunohistochemistry of primary paraffin-embedded tumor samples. The results were scored according to staining intensity and percentage of positive tumor cells resulting in an immune-reactive score (IRS) of 0-12. These results were correlated with clinicopathological characteristics and survival. TFF3 expression in our patient cohort exhibited a tendency towards improved overall and progression-free survival (PFS). In TFF3-positive serous and high-grade serous ovarian cancers, the median PFS was 27.6 months [95% confidence interval (CI): 0-55.7] vs. 15.2 months in TFF3-negative tumors (95% CI: 13.8-16.6) (P=0.183). The median overall survival was 53.9 months in TFF3-positive tumors (95% CI: Non-applicable) vs. 44.4 months in TFF3-negative cases (95% CI: 30.5-58.3) (P=0.36). TFF3 negativity was significantly associated with higher tumor grade (P=0.05). Based on our results, further studies are required in order to elucidate whether survival and chemosensitivity are affected by TFF3 expression in ovarian cancer.

Fascin-1 expression as stratification marker in borderline epithelial tumours of the ovary.

AIMS: To evaluate the actin-bundling protein fascin-1 (FSCN1) as marker for borderline ovarian tumours (BOTs). METHODS: We analysed a retrospective cohort of 140 BOTs with validated diagnosis by an independent pathologist. Immunohistochemical detection of FSCN1 was quantified as combined immunoreactive score (CIS) blinded to clinical patient data. Analyses were first performed for FSCN1 positive versus negative, and then verified using three categories derived from the observed distribution (negative, weak, strong; CIS 0, 1-2, 3-9). RESULTS: We detected FSCN1 positivity in 51.4%, and strong expression (CIS 3-9) in 14.3% of the samples. FSCN1 positivity was associated with serous subtype (p<0.001) and micropapillary pattern (p<0.001). Correlation with micropapillary pattern remained significant within the serous BOT (SBOT) subgroup (p=0.022). Strong FSCN1 expression (CIS 3-9) was associated both with the presence of implants (p=0.022), and a higher International Federation of Gynecology and Obstetrics (FIGO) stage (p=0.020). CONCLUSIONS: Our analysis links FSCN1 with SBOT with micropapillary pattern. Strong expression is associated with higher FIGO stage and the presence of implants, both related to elevated risk of recurrence. Hence, FSCN1 is an interesting marker worth further analyses of its prognostic value in BOTs.

The Influence of Host Factors on the Prognosis of Breast Cancer: Stroma and Immune Cell Components as Cancer Biomarkers.

In this paper, we will review the data on stromal components and immunological parameters in the cancer microenvironment as prognostic and predictive markers in breast cancer. Host immunological response to cancer has gained importance because of recent breakthroughs in immunotherapy. Currently, molecular and clinical subtyping of breast cancer is solely based on the molecular features of the cancer cells without considering the importance of stromal components. There is now clear evidence that infiltrating immune and inflammatory cells influence the biology and clinical course of breast cancer. However, the prognostic and predictive function of immune cells differs between breast cancer subtypes. Immune parameters are established and validated prognostic and predictive markers in triple negative and for HER2 positive breast cancers and may be ready to be used as stratification parameters in clinical trials and as adjunct variables when making clinical decisions. On the other hand, the prognostic and predictive impact is minimal in low grade, luminal A type breast cancers. The strong association between higher lymphocytic infiltration and better outcome (including greater chemotherapy sensitivity) in TNBC and HER2 positive cancers also raises novel therapeutic options that target immune cells to increase their activity. Immune markers also carry the potential to serve as predictive markers to select patients for immunotherapeutic regimens (e.g. checkpoint inhibitors).

The prognostic impact of age in different molecular subtypes of breast cancer.

Breast cancer is a heterogeneous entity composed of distinct molecular subgroups with different molecular and clinical features. We analyzed the association between molecular breast cancer subgroups, age at diagnosis, and prognosis in a compilation of publicly available gene expression datasets. Affymetrix gene expression data (U133A or U133Plus2.0 arrays) of 4467 breast cancers from 40 datasets were compiled and homogenized. Breast cancer subgroups were defined based on expression of ESR1, PR, HER2, and Ki67. Event-free survival was calculated as recurrence-free survival or distant metastasis-free survival if recurrence-free survival was not available. Young age at diagnosis is associated with higher frequency of triple negative and HER2 subtypes and lower frequency of luminal A breast cancers. The 5-year event-free survival rates of patients aged less than 40, between 40 and 50, and >50 years were 54.3 ± 3.5, 68.5 ± 1.9, and 70.4 ± 1.3 %, respectively. When controlling for breast cancer subtype, we found that age <40 years remained significantly associated with poor prognosis in triple negative breast cancer. The effect was modest in luminal tumors and not found in HER2 subtype. Both subtypes and age retained their significances in multivariate analysis. Association of age at diagnosis with molecular breast cancer subtype contributes to its important role as prognostic factor among patients with breast cancer. Still, within the group of triple negative breast cancer, young age <40 years has a significant prognostic value which was retained in multivariate analysis.

Genomic predictor of residual risk of recurrence after adjuvant chemotherapy and endocrine therapy in high risk estrogen receptor-positive breast cancers.

A subset of early stage estrogen receptor (ER)-positive breast cancers considered "high risk" for recurrence with endocrine therapy alone by current genomic prognostic predictors, such as Oncotype DX, is no longer high risk after receiving adjuvant chemotherapy. We hypothesized that a recently described gene expression-based outcome predictor adjuvant chemotherapy and endocrine therapy sensitivity (ACES) could re-stratify these patients into high and low risk groups for relapse when treated with both chemo- and endocrine therapies. ACES involves four separate modules (endocrine sensitivity, chemotherapy sensitivity, chemotherapy resistance, and survival prediction) that yield a prediction for good or poor outcome with current standard of care multimodality therapy. ACES was applied to Affymetrix gene expression data from 2 retrospectively collected ER-positive and HER2-negative patient cohorts that were uniformly treated with adjuvant endocrine and chemotherapy (n = 250). Each sample was first risk stratified by a genomic surrogate of Oncotype DX, and the high risk patients (n = 76) were re-stratified by ACES. Recurrence-free survival (RFS) was evaluated with ACES risk categories. The Oncotype DX high risk but ACES good prognosis patients (n = 24, 32%) had an RFS of 95% compared to 76% in the poor prognosis group (n = 52; log-rank p = 0.033) at 5 years. ACES risk category remained an independent predictor in multivariate analysis after adjusting for age, T-stage, and lymph node involvement at diagnosis (hazard ratio 0.15; p = 0.072). Tertiary risk prediction that takes into account chemotherapy and endocrine sensitivity, and baseline prognosis may help identify high risk ER-positive patients who have excellent survival after chemotherapy.

Acid ceramidase is associated with an improved prognosis in both DCIS and invasive breast cancer.

Acid ceramidase (ASAH1) a key enzyme of sphingolipid metabolism converting pro-apoptotic ceramide to sphingosine has been shown to be overexpressed in various cancers. We previously demonstrated higher expression of ASAH1 in ER positive compared to ER negative breast cancer. In the current study we performed subtype specific analyses of ASAH1 gene expression in invasive and non invasive breast cancer. We show that expression of ASAH1 is mainly associated with luminal A - like cancers which are known to have the best prognosis of all breast cancer subtypes. Moreover tumors with high ASAH1 expression among the other subtypes are also characterized by an improved prognosis. The good prognosis of tumors with high ASAH1 is independent of the type of adjuvant treatment in breast cancer and is also detected in non small cell lung cancer patients. Moreover, even in pre-invasive DCIS of the breast ASAH1 is associated with a luminal phenotype and a reduced frequency of recurrences. Thus, high ASAH1 expression is generally associated with an improved prognosis in invasive breast cancer independent of adjuvant treatment and could also be valuable as prognostic factor for pre-invasive DCIS.

OPG and PgR show similar cohort specific effects as prognostic factors in ER positive breast cancer.

The RANK/RANKL/OPG pathway is well known for bone destruction in skeletal metastases but has also been implicated in osteoclast-independent roles in tumorigenesis and de novo metastasis. Experimental data suggest contribution of progesterone to tumorigenesis may be mediated by RANKL. Importantly, modulation of this pathway became possible through the availability of denosumab, an artificial counterpart of OPG, but significant gaps remain in the translation of preclinical findings on the pathway. We analyzed gene expression of RANK, RANKL and OPG from 40 Affymetrix datasets encompassing 4467 primary breast cancers and focused on ER positive disease. We did not observe a significant prognostic value of RANK and RANKL mRNA expression. In contrast, OPG was associated with a better prognosis among 1941 ER positive cancers (HR 0.64, 95% CI 0.53-0.77; P < 0.0001) using a cutoff from its highly bimodal expression. We detected considerable heterogeneity regarding the prognostic value of OPG between different datasets. This heterogeneity could neither be attributed to technical reasons nor to differences in standard clinical parameters or treatments of the cohorts. Interestingly, the prognostic value of the progesterone receptor and of OPG showed similar cohort specific effects. Still both factors were no surrogates for each other but contributed independent prognostic value in multivariate analyses. Thus, both OPG and PgR are independently associated with good prognosis in ER positive breast cancer. However both markers share common cohort specific differences in contrast to proliferation markers as Ki67 which may be based on the underlying biology.

Control of dataset bias in combined Affymetrix cohorts of triple negative breast cancer.

Heterogenous subtypes of breast cancer need to be analyzed separately. Pooling of datasets can provide reasonable sample sizes but dataset bias is an important concern. We assembled a combined dataset of 579 Affymetrix microarrays from triple negative breast cancer (TNBC) in Gene Expression Omnibus (GEO) series GSE31519. We developed a method for selecting comparable datasets and to control for the amount of dataset bias of individual probesets.

Proliferation and estrogen signaling can distinguish patients at risk for early versus late relapse among estrogen receptor positive breast cancers.

INTRODUCTION: We examined if a combination of proliferation markers and estrogen receptor (ER) activity could predict early versus late relapses in ER-positive breast cancer and inform the choice and length of adjuvant endocrine therapy. METHODS: Baseline affymetrix gene-expression profiles from ER-positive patients who received no systemic therapy (n = 559), adjuvant tamoxifen for 5 years (cohort-1: n = 683, cohort-2: n = 282) and from 58 patients treated with neoadjuvant letrozole for 3 months (gene-expression available at baseline, 14 and 90 days) were analyzed. A proliferation score based on the expression of mitotic kinases (MKS) and an ER-related score (ERS) adopted from Oncotype DX® were calculated. The same analysis was performed using the Genomic Grade Index as proliferation marker and the luminal gene score from the PAM50 classifier as measure of estrogen-related genes. Median values were used to define low and high marker groups and four combinations were created. Relapses were grouped into time cohorts of 0-2.5, 0-5, 5-10 years. RESULTS: In the overall 10 years period, the proportional hazards assumption was violated for several biomarker groups indicating time-dependent effects. In tamoxifen-treated patients Low-MKS/Low-ERS cancers had continuously increasing risk of relapse that was higher after 5 years than Low-MKS/High-ERS cancers [0 to 10 year, HR 3.36; p = 0.013]. High-MKS/High-ERS cancers had low risk of early relapse [0-2.5 years HR 0.13; p = 0.0006], but high risk of late relapse which was higher than in the High-MKS/Low-ERS group [after 5 years HR 3.86; p = 0.007]. The High-MKS/Low-ERS subset had most of the early relapses [0 to 2.5 years, HR 6.53; p < 0.0001] especially in node negative tumors and showed minimal response to neoadjuvant letrozole. These findings were qualitatively confirmed in a smaller independent cohort of tamoxifen-treated patients. Using different biomarkers provided similar results. CONCLUSIONS: Early relapses are highest in highly proliferative/low-ERS cancers, in particular in node negative tumors. Relapses occurring after 5 years of adjuvant tamoxifen are highest among the highly-proliferative/high-ERS tumors although their risk of recurrence is modest in the first 5 years on tamoxifen. These tumors could be the best candidates for extended endocrine therapy.