Dynamics of breast-cancer relapse reveal late-recurring ER-positive genomic subgroups.

The rates and routes of lethal systemic spread in breast cancer are poorly understood owing to a lack of molecularly characterized patient cohorts with long-term, detailed follow-up data. Long-term follow-up is especially important for those with oestrogen-receptor (ER)-positive breast cancers, which can recur up to two decades after initial diagnosis1-6. It is therefore essential to identify patients who have a high risk of late relapse7-9. Here we present a statistical framework that models distinct disease stages (locoregional recurrence, distant recurrence, breast-cancer-related death and death from other causes) and competing risks of mortality from breast cancer, while yielding individual risk-of-recurrence predictions. We apply this model to 3,240 patients with breast cancer, including 1,980 for whom molecular data are available, and delineate spatiotemporal patterns of relapse across different categories of molecular information (namely immunohistochemical subtypes; PAM50 subtypes, which are based on gene-expression patterns10,11; and integrative or IntClust subtypes, which are based on patterns of genomic copy-number alterations and gene expression12,13). We identify four late-recurring integrative subtypes, comprising about one quarter (26%) of tumours that are both positive for ER and negative for human epidermal growth factor receptor 2, each with characteristic tumour-driving alterations in genomic copy number and a high risk of recurrence (mean 47-62%) up to 20 years after diagnosis. We also define a subgroup of triple-negative breast cancers in which cancer rarely recurs after five years, and a separate subgroup in which patients remain at risk. Use of the integrative subtypes improves the prediction of late, distant relapse beyond what is possible with clinical covariates (nodal status, tumour size, tumour grade and immunohistochemical subtype). These findings highlight opportunities for improved patient stratification and biomarker-driven clinical trials.

The relevance of phosphorylated forms of estrogen receptor in human breast cancer in vivo.

Estrogen receptor (ER)alpha activity is regulated by phosphorylation at several sites. Recently several antibodies specific for individual phosphorylated sites within ERalpha have became available. Validation and use of these antibodies suggests that several forms of phosphorylated ERalpha can be detected in multiple ER+ human breast tumor samples, thus providing relevance for investigating the regulation and function of phosphorylated ERalpha in human breast cancer. Generally, the phosphorylated ERalpha isoforms are associated with parameters that suggest that they are markers of an intact estrogen dependent signaling pathway and better clinical outcome with respect to tamoxifen therapy. Profiling of phosphorylated ERalpha may provide better biomarkers of endocrine therapy response over and above those currently available.

Immunohistochemical validation of multiple phospho-specific epitopes for estrogen receptor alpha (ERalpha) in tissue microarrays of ERalpha positive human breast carcinomas.

Estrogen receptor alpha (ERalpha) activity is regulated by phosphorylation at several sites. Recently several antibodies specific for individual phosphorylated sites within ERalpha have became available. Such antibodies potentially provide invaluable tools to gain insight into the relevance in vivo of phosphorylated ERalpha in human breast tumors. However, validation of these antibodies for immunohistochemistry in particular is necessary in the first instance. In this study we have investigated the usefulness of several antibodies generated to specific phosphorylated sites within ERalpha for immunohistochemistry of formalin-fixed, paraffin-embedded human breast cancer biopsy samples. As well, these data demonstrate for the first time, the detection of multiple phosphorylated ERalpha forms in breast cancer (P-S104/106-ERalpha, P-S118-ERalpha, P-S167-ERalpha, P-S282-ERalpha, P-S294-ERalpha, P-T311-ERalpha, and P-S559-ERalpha) suggesting the possibility that profiling of phosphorylated ERalpha isoforms might be useful in selecting subgroups of breast cancer patients that would benefit from endocrine therapy.

Influence of evolution in tumor biobanking on the interpretation of translational research.

PURPOSE: Translational cancer research increasingly relies on human tissue biospecimens and this has coincided with a shift in tissue biobanking approach. Newer biobanks (post year 2000) deploy standard operating procedures to reduce variability around biospecimen collection. Because current translational research is based on pre-2000 and post-2000 era biospecimens, we consider whether the collection era may influence gene expression data. DESIGN: We compared the range of breast tumor collection times from pre-2000 and post-2000 era biobanks and compared estrogen receptor (ER) protein expression with collection time. We then collected 10 breast tumor biospecimens under a standardized protocol and examined whether the expression of c-myc and ER was influenced by storage on ice < or = 24 hours. RESULTS: The range of collection times achieved at a pre-2000 versus post-2000 era biobank differed. Thirty-two percent of biospecimens were cryopreserved within 30 minutes at the pre-2000 era biobank versus 76% at the post-2000 era biobank. Collection time and ER protein level was inversely correlated (r = -0.19, P = 0.025; n = 137). We observed a wide range in initial c-myc and ER mRNA levels (50- versus 130-fold). Although mRNA levels of both genes declined with increasing collection time, the rate of change differed because c-myc was significantly reduced after 24 hours (mean reduction to 79% of initial) versus ER (94% of initial). CONCLUSION: The overall shift in biobanking around the year 2000 is reflected in the ranges of collection times associated with pre-2000 and post-2000 era biobanks. Because collection time can differentially alter gene expression, the biospecimen collection era should be considered in gene expression studies.

Reduced expression of the small leucine-rich proteoglycans, lumican, and decorin is associated with poor outcome in node-negative invasive breast cancer.

PURPOSE: To examine the prognostic significance of lumican and decorin, two abundant small leucine-rich proteoglycans in breast tissue stroma. EXPERIMENTAL DESIGN: Lumican and decorin expression was examined in a cohort of 140 invasive breast carcinomas by Western blot analysis. All cases were axillary lymph node-negative and treated by adjuvant endocrine therapy. RESULTS: Lumican and decorin expression was highly correlated (r = 0.45, P < 0.0001), but although low levels of lumican were associated with large tumor size (P = 0.0496), negative estrogen receptor (P = 0.0024) and progesterone receptor status (P = 0.0116), and increased host inflammatory response (P = 0.0077), low decorin levels were associated only with large tumor size (P = 0.0496). However, using univariate analysis, low levels of lumican and decorin were both associated with a shorter time to progression (P = 0.0013 and 0.0262) and poorer survival (P = 0.001 and 0.0076). In multivariate analysis using the Cox regression model, low decorin was also shown to be an independent predictive factor for recurrence (hazard ratio 2.25: 95% confidence interval 1-5, P = 0.047) and survival (hazard ratio 3.39: 95% confidence interval 1.2-9.6, P = 0.021). CONCLUSIONS: These results suggest that low levels of small leucine-rich proteoglycans in breast tumors may be associated with a worse prognosis in lymph node-negative invasive breast carcinomas and warrant further study with larger patient cohorts.