Gene expression profiling to predict the risk of locoregional recurrence in breast cancer: a pooled analysis

Validation of a breast cancer assay for radiotherapy omission: an individual participant data meta-analysis

BACKGROUND

There are currently no molecular tests to identify individual breast cancers where radiotherapy (RT) offers no benefit. Profile for the Omission of Local Adjuvant Radiotherapy (POLAR) is a 16-gene molecular signature developed to identify low-risk cancers where RT will not further reduce recurrence rates.

METHODS

An individual participant data meta-analysis was performed in 623 patients of node-negative estrogen receptor-positive and HER2-negative early breast cancer enrolled in 3 RT randomized trials for whom primary tumor material was available for analysis. A Cox proportional hazards model on time to locoregional recurrence was used to test the interaction between POLAR score and RT.

RESULTS

A total of 429 (69%) patients' tumors had a high POLAR score, and 194 (31%) had a low score. Patients with high POLAR score had, in the absence of RT, a 10-year cumulative incidence of locoregional recurrence (20%, 95% confidence interval [CI] = 15% to 26%, vs 5%, [CI] 2% to 11%) for those with a low score. Patients with a high POLAR score had a large benefit from RT (hazard ratio [HR] for RT vs no RT = 0.37, 95% CI = 0.23 to 0.60; P < .001). In contrast, there was no evidence of benefit from RT for patients with a low POLAR score (HR = 0.92, 95% CI = 0.42 to 2.02; P = .832). The test for interaction between RT and POLAR was statistically significant (P = .022).

CONCLUSIONS

POLAR is not only prognostic for locoregional recurrence but also predictive of benefit from RT in selected patients. Patients aged 50 years and older with estrogen receptor-positive and HER2-negative disease and a low POLAR score could consider omitting adjuvant RT. Further validation in contemporary clinical cohorts is required.

Biomarker-Directed Radiotherapy in Breast Cancer: A Narrative Review

Importance

Integration of molecular biomarker information into systemic therapy has become standard practice in breast cancer care. However, its implementation in guiding radiotherapy (RT) is slower. Although postoperative RT is recommended for most patients after breast-conserving surgery and, depending on risk factors, following mastectomy, emerging evidence has indicated that patients with low scores on gene expression signatures or selected clinical-pathological features may have very low local recurrence rates. This narrative review explored the potential of biomarker-directed personalized RT approaches, which may optimize treatment strategies and be associated with improved patient outcomes and experiences.

Observations

Distinctions between prognostic and predictive biomarkers were highlighted, emphasizing the importance of analytical and clinical validity in biomarker-based studies. Findings from studies investigating the prognostic and predictive value of various genomic signatures and immunohistochemical markers for guiding breast RT were presented. These included the Adjuvant Radiotherapy Intensification Classifier and the Profile for the Omission of Local Adjuvant Radiation, which have shown potential in predicting RT benefits. The genomic-adjusted radiation dose and role of tumor-infiltrating lymphocytes were also discussed. Ongoing clinical trials exploring the use of biomarkers in ductal carcinoma in situ and invasive breast cancer to refine RT decision-making were illustrated.

Conclusions and Relevance

The results of this narrative review suggest that evidence-based shared decision-making is crucial to optimize treatment according to the individual's predicted benefits and risks along with their personal preferences. Incorporation of biomarker-directed approaches in RT for breast cancer may hold promise for personalized treatment, potentially facilitating omission of RT for patients at low risk of recurrence, while identifying those who may benefit from intensified therapy. This personalized RT approach may be associated with improved clinical outcomes and quality of life and facilitate decision-making for people with breast cancer. However, there remains a need for robust clinical and analytical validation of biomarkers to ensure reliability and clinical utility for RT optimization.

Clinical Biomarkers of Tumour Radiosensitivity and Predicting Benefit from Radiotherapy: A Systematic Review

Modern advanced radiotherapy techniques have improved the precision and accuracy of radiotherapy delivery, with resulting plans being highly personalised based on individual anatomy. Adaptation for individual tumour biology remains elusive. There is an unmet need for biomarkers of intrinsic radiosensitivity that can predict tumour response to radiation to facilitate individualised decision-making, dosing and treatment planning. Over the last few decades, the use of high throughput molecular biology technologies has led to an explosion of newly discovered cancer biomarkers. Gene expression signatures are now used routinely in clinic to aid decision-making regarding adjuvant systemic therapy. They have great potential as radiotherapy biomarkers. A previous systematic review published in 2015 reported only five studies of signatures evaluated for their ability to predict radiotherapy benefits in clinical cohorts. This updated systematic review encompasses the expanded number of studies reported in the last decade. An additional 27 studies were identified. In total, 22 distinct signatures were recognised (5 pre-2015, 17 post-2015). Seventeen signatures were 'radiosensitivity' signatures and five were breast cancer prognostic signatures aiming to identify patients at an increased risk of local recurrence and therefore were more likely to benefit from adjuvant radiation. Most signatures (15/22) had not progressed beyond the discovery phase of development, with no suitable validated clinical-grade assay for application. Very few signatures (4/17 'radiosensitivity' signatures) had undergone any laboratory-based biological validation of their ability to predict tumour radiosensitivity. No signatures have been assessed prospectively in a phase III biomarker-led trial to date and none are recommended for routine use in clinical guidelines. A phase III prospective evaluation is ongoing for two breast cancer prognostic signatures. The most promising radiosensitivity signature remains the radiosensitivity index (RSI), which is used to calculate a genomic adjusted radiation dose (GARD). There is an ongoing phase II prospective biomarker-led study of RSI/GARD in triple negative breast cancer. The results of these trials are eagerly anticipated over the coming years. Future work in this area should focus on (1) robust biological validation; (2) building biobanks alongside large radiotherapy randomised controlled trials with dose variance (to demonstrate an interaction between radiosensitivity signature and dose); (3) a validation of clinical-grade cost-effective assays that are deliverable within current healthcare infrastructure; and (4) an integration with biomarkers of other determinants of radiation response.

Locoregional Breast Cancer Recurrence in the European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 MINDACT Trial: Analysis of Risk Factors Including the 70-Gene Signature

PURPOSE

A number of studies are currently investigating de-escalation of radiation therapy in patients with a low risk of in-breast relapses on the basis of clinicopathologic factors and molecular tests. We evaluated whether 70-gene risk score is associated with risk of locoregional recurrence (LRR) and estimated 8-year cumulative incidences for LRR in patients with early-stage breast cancer treated with breast conservation.

METHODS

In this exploratory substudy of European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 MINDACT trial, we evaluated women with a known clinical and genomic 70-gene risk score test result and who had breast-conserving surgery (BCS). The primary end point was LRR at 8 years, estimated by cumulative incidences. Distant metastasis and death were considered competing risks.

RESULTS

Among 6,693 enrolled patients, 5,470 (81.7%) underwent BCS, of whom 98% received radiotherapy. At 8-year follow-up, 189 patients experienced a LRR, resulting in an 8-year cumulative incidence of 3.2% (95% CI, 2.7 to 3.7). In patients with a low-risk 70-gene signature, the 8-year LRR incidence was 2.7% (95% CI, 2.1 to 3.3). In univariable analysis, adjusted for chemotherapy, five of 12 variables were associated with LRR, including the 70-gene signature. In multivariable modeling, adjuvant endocrine therapy and to a lesser extent tumor size and grade remained significantly associated with LRR.

CONCLUSION

This exploratory analysis of the MINDACT trial estimated an 8-year low LRR rate of 3.2% after BCS. The 70-gene signature was not independently predictive of LRR perhaps because of the low number of events observed and currently cannot be used in clinical decision making regarding LRR. The overall low number of events does provide an opportunity to design trials toward de-escalation of local therapy.

Individualising radiation therapy decisions in breast cancer patients based on tumour infiltrating lymphocytes and genomic biomarkers

Radiation therapy (RT) has long been fundamental for the curative treatment of breast cancer. While substantial progress has been made in the anatomical and technological precision of RT delivery, and some approaches to de-escalate or omit RT based on clinicopathologic features have been successful, there remain substantial opportunities to refine individualised RT based on tumour biology. A major area of clinical and research interest is to ascertain the individualised risk of loco-regional recurrence to direct treatment decisions regarding escalation and de-escalation of RT. Patient-tailored treatment with RT is considerably lagging behind compared with the massive progress made in the field of personalised medicine that currently mainly applies to decisions on the use of systemic therapy or targeted agents. Herein we review select literature surrounding the use of tumour genomic biomarkers and biomarkers of the immune system, including tumour infiltrating lymphocytes (TILs), within the management of breast cancer, specifically as they relate to progress in moving toward analytically validated and clinically tested biomarkers utilized in RT.

Breast Cancer Cryoablation in the Multidisciplinary Setting: Practical Guidelines for Patients and Physicians

Breast cancer cryoablation has emerged as a minimally invasive alternative to lumpectomy for treating early-stage breast cancer. However, no consensus exists on what should be considered the standard of care for the multidisciplinary management of patients treated with breast cancer cryoablation. In lieu of national guidelines, this review of the literature provides a multidisciplinary framework and an evidence-based discussion of the integration of "standard of care practices" in the comprehensive management of breast cancer cryoablation patients.

Evaluation and comparison of different breast cancer prognosis scores based on gene expression data

BACKGROUND

Breast cancer is one of the three most common cancers worldwide and is the most common malignancy in women. Treatment approaches for breast cancer are diverse and varied. Clinicians must balance risks and benefits when deciding treatments, and models have been developed to support this decision-making. Genomic risk scores (GRSs) may offer greater clinical value than standard clinicopathological models, but there is limited evidence as to whether these models perform better than the current clinical standard of care.

METHODS

PREDICT and GRSs were adapted using data from the original papers. Univariable Cox proportional hazards models were produced with breast cancer-specific survival (BCSS) as the outcome. Independent predictors of BCSS were used to build multivariable models with PREDICT. Signatures which provided independent prognostic information in multivariable models were incorporated into the PREDICT algorithm and assessed for calibration, discrimination and reclassification.

RESULTS

EndoPredict, MammaPrint and Prosigna demonstrated prognostic power independent of PREDICT in multivariable models for ER-positive patients; no score predicted BCSS in ER-negative patients. Incorporating these models into PREDICT had only a modest impact upon calibration (with absolute improvements of 0.2-0.8%), discrimination (with no statistically significant c-index improvements) and reclassification (with 4-10% of patients being reclassified).

CONCLUSION

Addition of GRSs to PREDICT had limited impact on model fit or treatment received. This analysis does not support widespread adoption of current GRSs based on our implementations of commercial products.

Comparison of hazard models with and without consideration of competing risks to assess the effect of neoadjuvant chemotherapy on locoregional recurrence among breast cancer patients

Context

While analyzing locoregional recurrences (LRRs), it is necessary to consider distant metastasis as a competing event. Because, later one is more fatal than LRR. It may change ongoing treatment of breast cancer and may alter the chance of LRR. Although some earlier studies assessed the effect of neoadjuvant chemotherapy (NACT) on LRR, they did not use competing risk regression model for it.

Aims

To identify the risk factors and predict LRR using competing risk hazard model and to compare them with those using conventional hazard model.

Settings and Design

This was a retrospective study from a tertiary care cancer hospital in India.

Subjects and Methods

Data of 2114 breast cancer patients undergoing surgery were used from patient's record files (1993-2014).

Statistical Analysis

Fine and Gray competing risk regression was used to model time from surgery to LRR, considering distant metastasis and death as the competing events. Further, cause-specific Cox regression was used to model time from surgery to LRR without considering competing risk.

Results

Greater than ten positive nodes (hazard ratio [HR] [95% confidence interval (CI)]: 2.19 [1.18-4.03]), skin involvement (HR [95% CI]: 2.75 [1.50-5.05]), NACT (HR [95% CI]: 1.90 [1.06-3.40]), invasive tumor in inner quadrant (HR [95% CI]: 1.78 [0.98-3.24]), and postoperative radiotherapy (HR [95% CI]: 0.52 [0.29-0.94]) were found to be significantly associated with LRR. However, conventional survival analysis ignoring competing risk overestimated cumulative incidence function and underestimated survival. Competing risk regression provided relatively more precise CI. Conclusions: Competing risks, if any, need to be incorporated in the survival analysis. NACT was found to be associated with higher risk for LRR, which may be because of administering it mainly to patients with bad prognosis.

Conclusions

Competing risks, if any, need to be incorporated in the survival analysis. NACT was found to be associated with higher risk for LRR, which may be because of administering it mainly to patients with bad prognosis.

Genomically Guided Breast Radiation Therapy: A Review of the Current Data and Future Directions

Purpose

To highlight the current evidence and the limitations in data to support a personalized approach in breast oncology radiation therapy management and define steps needed for clinical implementation.

Methods and Materials

A critical review of the current literature on the use of genomics in breast radiation therapy was undertaken by a group of breast radiation oncologists to discuss current data, future directions, and challenges.

Results

A summary of the existing data, ongoing clinical trials, and future directions is provided. The authors note many groups have developed radiation-specific genomic assays, which demonstrate promise in prediction of local control and benefit from radiation therapy; however, prospective validation of their utility is needed. Limitations continue to exist in our understanding of tumor biology and how it can be integrated into clinical practice.

Conclusions

Given the relative ubiquity of breast radiation therapy, the variety of dose and fractionation approaches, and the current data to support a personalized approach, it is our belief that the delivery of breast radiation therapy is uniquely poised for a genomically personalized radiation therapy approach. Prospective clinical trials implementing genomic signatures are needed at this time to advance the field.

PAM-50 predicts local recurrence after breast cancer surgery in postmenopausal patients with ER+/HER2- disease: results from 1204 patients in the randomized ABCSG-8 trial

BACKGROUND

The aim of this study was to investigate whether the PAM-50-based 46-gene assay carries prognostic value for risk of local recurrence of breast cancer.

METHODS

The Austrian Breast and Colorectal Cancer Study Group (ABCSG) 8 RCT compared 5 years of tamoxifen with tamoxifen for 2 years followed by anastrozole for 3 years in postmenopausal women with endocrine receptor-positive breast cancer. This study included patients from the trial who had breast-conserving surgery for whom tumour blocks were available for PAM-50 analysis.

RESULTS

Tumour blocks from 1204 patients who had breast-conserving surgery were available for the PAM-50 analysis, and 1034 of these received radiotherapy. After a median follow-up of 10.8 years, 23 local events had been observed, corresponding to an overall local recurrence risk of 2.2 per cent. Univariable competing-risk analysis demonstrated that patients at low risk according to PAM-50 analysis (risk-of-recurrence (ROR) score less than 57) had a significantly lower incidence of local recurrence than those in the high-risk group at 5 years (0.1 (95 per cent c.i. 0 to 0.7) versus 2.2 (0.9 to 4.6) per cent respectively; subhazard ratio (SHR) 17.18, 95 per cent c.i. 2.06 to 142.88; P = 0.009) and 10 years (0.9 (0.4 to 2.0) versus 3.8 (1.9 to 6.6) per cent; SHR 4.76, 1.72 to 13.17; P = 0.003). Multivariable analyses that included ROR score, age, tumour size, nodal status, type of surgery, tumor grade, and trial-specific endocrine therapy confirmed that ROR score was an independent prognostic factor for risk of local recurrence. Analysis of the women randomized to radiotherapy or control after breast conservation showed that PAM-50 was not predictive of radiotherapy effect.

CONCLUSION

PAM-50 can be used as a prognostic tool for local recurrence risk in postmenopausal women with hormone receptor-positive breast cancer treated with endocrine therapy. The test was not predictive for the benefit of radiotherapy.

Personalization in Modern Radiation Oncology: Methods, Results and Pitfalls. Personalized Interventions and Breast Cancer

Breast cancer, the most frequent malignancy in women worldwide, is a heterogeneous group of diseases, characterized by distinct molecular aberrations. In precision medicine, radiation oncology for breast cancer aims at tailoring treatment according to tumor biology and each patient’s clinical features and genetics. Although systemic therapies are personalized according to molecular sub-type [i.e. endocrine therapy for receptor-positive disease and anti-human epidermal growth factor receptor 2 (HER2) therapy for HER2-positive disease] and multi-gene assays, personalized radiation therapy has yet to be adopted in the clinical setting. Currently, attempts are being made to identify prognostic and/or predictive factors, biomarkers, signatures that could lead to personalized treatment in order to select appropriate patients who might, or might not, benefit from radiation therapy or whose radiation therapy might be escalated or de-escalated in dosages and volumes. This overview focuses on what has been achieved to date in personalized post-operative radiation therapy and individual patient radiosensitivity assessments by means of tumor sub-types and genetics.

Breast-conserving Surgery Without Radiation Therapy for Invasive Cancer

Radiotherapy (RT) after breast-conserving surgery (BCS) halves the risk of local recurrence, and it is considered the standard of care for the vast majority of patients with early invasive breast cancer. However, the majority of patients treated with BCS will not recur locally, even in the absence of RT. Over the past several decades, the improved and widespread use of systemic therapy has significantly decreased the rate of local recurrence. This has stimulated interest in identifying favorable patient subsets not requiring RT. Randomized controlled trials have shown in women aged ≥ 70 years with stage I estrogen receptor-positive (ER⁺) tumors, RT can be safely omitted. To better identify patients with favorable prognosis, ongoing trials have incorporated biological markers and genomic assays. Despite great research efforts to de-escalate locoregional treatment, real-world data indicate that omission of RT in low-risk patients is inconsistent. Better decision-making is warranted to reduce overtreatment and financial toxicity.

Association Between 21-Gene Assay Recurrence Score and Locoregional Recurrence Rates in Patients With Node-Positive Breast Cancer

Importance

The 21-gene assay recurrence score is increasingly used to personalize treatment recommendations for systemic therapy in postmenopausal women with estrogen receptor (ER)- or progesterone receptor (PR)-positive, node-positive breast cancer; however, the relevance of the 21-gene assay to radiotherapy decisions remains uncertain.

Objective

To examine the association between recurrence score and locoregional recurrence (LRR) in a postmenopausal patient population treated with adjuvant chemotherapy followed by tamoxifen or tamoxifen alone.

Design, Setting, and Participants

This cohort study was a retrospective analysis of the Southwest Oncology Group S8814, a phase 3 randomized clinical trial of postmenopausal women with ER/PR-positive, node-positive breast cancer treated with tamoxifen alone, chemotherapy followed by tamoxifen, or concurrent tamoxifen and chemotherapy. Patients at North American clinical centers were enrolled from June 1989 to July 1995. Medical records from patients with recurrence score information were reviewed for LRR and radiotherapy use. Primary analysis included 316 patients and excluded 37 who received both mastectomy and radiotherapy, 9 who received breast-conserving surgery without documented radiotherapy, and 5 with unknown surgical type. All analyses were performed from January 22, 2016, to August 9, 2019.

Main Outcomes and Measures

The LRR was defined as a recurrence in the breast; chest wall; or axillary, infraclavicular, supraclavicular, or internal mammary lymph nodes. Time to LRR was tested with log-rank tests and Cox proportional hazards regression for multivariate models.

Results

The final cohort of this study comprised 316 women with a mean (range) age of 60.4 (44-81) years. Median (interquartile range) follow-up for those without LRR was 8.7 (7.0-10.2) years. Seven LRR events (5.8%) among 121 patients with low recurrence score and 27 LRR events (13.8%) among 195 patients with intermediate or high recurrence score occurred. The estimated 10-year cumulative incidence rates were 9.7% for those with a low recurrence score and 16.5% for the group with intermediate or high recurrence score (P = .02). Among patients who had a mastectomy without radiotherapy (n = 252), the differences in the 10-year actuarial LRR rates remained significant: 7.7 % for the low recurrence score group vs 16.8% for the intermediate or high recurrence score group (P = .03). A multivariable model controlling for randomized treatment, number of positive nodes, and surgical type showed that a higher recurrence score was prognostic for LRR (hazard ratio [HR], 2.36; 95% CI, 1.02-5.45; P = .04). In a subset analysis of patients with a mastectomy and 1 to 3 involved nodes who did not receive radiation therapy, the group with a low recurrence score had a 1.5% rate of LRR, whereas the group with an intermediate or high recurrence score had a 11.1% LRR (P = .051).

Conclusions and Relevance

This study found that higher recurrence scores were associated with increased LRR after adjustment for treatment, type of surgical procedure, and number of positive nodes. This finding suggests that the recurrence score may be used, along with accepted clinical variables, to assess the risk of LRR during radiotherapy decision-making.

A case-control study to identify molecular risk factors for local recurrence in young breast cancer patients

PURPOSE

To investigate risk factors for local recurrence (LR) after breast conserving therapy in young breast cancer patients randomized in the "Young Boost Trial".

MATERIAL & METHODS

In the "Young Boost Trial" 2421 patients ≤50 years old were randomized between a 16 Gy and 26 Gy boost after breast conserving surgery and whole breast radiation (50 Gy). We performed a case-control study comparing patients who developed a LR (cases) and for each of them three control patients free of recurrence (controls). Clinicopathological factors, copy number- and gene expression profiles of primary tumors were compared between cases and controls, and between primary tumors and local recurrences.

RESULTS

The cumulative 5-year LR rate was 1.07% (95% CI 0.72-1.59%) and 10-year LR rate 2.56% (1.81-3.62%). Analysis of a subset of primary tumors and local recurrences showed similar histopathological characteristics (n = 15), copy number (n = 13) and gene expression profiles (n = 14). Basal subtype was strongly associated with LR in univariable and multivariable analysis. Gains of CCND1 were identified more frequently among controls, while more frequent gains of FGFR1 and IGF1R were observed among cases. Upregulation of genes involved in the p53-pathway was observed in recurring tumors compared to non-recurring tumors. We could not identify a genomic classifier for LR.

CONCLUSIONS

All investigated local recurrences were true genomic recurrences. Although differences in copy number variation and gene expression pathways were observed in recurring tumors compared to non-recurring tumors, no genomic classifier for LR could be identified.

Tumour profiling tests to guide adjuvant chemotherapy decisions in early breast cancer: a systematic review and economic analysis

BACKGROUND

Breast cancer and its treatment can have an impact on health-related quality of life and survival. Tumour profiling tests aim to identify whether or not women need chemotherapy owing to their risk of relapse.

OBJECTIVES

To conduct a systematic review of the effectiveness and cost-effectiveness of the tumour profiling tests oncotype DX^® (Genomic Health, Inc., Redwood City, CA, USA), MammaPrint^® (Agendia, Inc., Amsterdam, the Netherlands), Prosigna^® (NanoString Technologies, Inc., Seattle, WA, USA), EndoPredict^® (Myriad Genetics Ltd, London, UK) and immunohistochemistry 4 (IHC4). To develop a health economic model to assess the cost-effectiveness of these tests compared with clinical tools to guide the use of adjuvant chemotherapy in early-stage breast cancer from the perspective of the NHS and Personal Social Services.

DESIGN

A systematic review and health economic analysis were conducted.

REVIEW METHODS

The systematic review was partially an update of a 2013 review. Nine databases were searched in February 2017. The review included studies assessing clinical effectiveness in people with oestrogen receptor-positive, human epidermal growth factor receptor 2-negative, stage I or II cancer with zero to three positive lymph nodes. The economic analysis included a review of existing analyses and the development of a de novo model.

RESULTS

A total of 153 studies were identified. Only one completed randomised controlled trial (RCT) using a tumour profiling test in clinical practice was identified: Microarray In Node-negative Disease may Avoid ChemoTherapy (MINDACT) for MammaPrint. Other studies suggest that all the tests can provide information on the risk of relapse; however, results were more varied in lymph node-positive (LN+) patients than in lymph node-negative (LN0) patients. There is limited and varying evidence that oncotype DX and MammaPrint can predict benefit from chemotherapy. The net change in the percentage of patients with a chemotherapy recommendation or decision pre/post test ranged from an increase of 1% to a decrease of 23% among UK studies and a decrease of 0% to 64% across European studies. The health economic analysis suggests that the incremental cost-effectiveness ratios for the tests versus current practice are broadly favourable for the following scenarios: (1) oncotype DX, for the LN0 subgroup with a Nottingham Prognostic Index (NPI) of > 3.4 and the one to three positive lymph nodes (LN1-3) subgroup (if a predictive benefit is assumed); (2) IHC4 plus clinical factors (IHC4+C), for all patient subgroups; (3) Prosigna, for the LN0 subgroup with a NPI of > 3.4 and the LN1-3 subgroup; (4) EndoPredict Clinical, for the LN1-3 subgroup only; and (5) MammaPrint, for no subgroups.

LIMITATIONS

There was only one completed RCT using a tumour profiling test in clinical practice. Except for oncotype DX in the LN0 group with a NPI score of > 3.4 (clinical intermediate risk), evidence surrounding pre- and post-test chemotherapy probabilities is subject to considerable uncertainty. There is uncertainty regarding whether or not oncotype DX and MammaPrint are predictive of chemotherapy benefit. The MammaPrint analysis uses a different data source to the other four tests. The Translational substudy of the Arimidex, Tamoxifen, Alone or in Combination (TransATAC) study (used in the economic modelling) has a number of limitations.

CONCLUSIONS

The review suggests that all the tests can provide prognostic information on the risk of relapse; results were more varied in LN+ patients than in LN0 patients. There is limited and varying evidence that oncotype DX and MammaPrint are predictive of chemotherapy benefit. Health economic analyses indicate that some tests may have a favourable cost-effectiveness profile for certain patient subgroups; all estimates are subject to uncertainty. More evidence is needed on the prediction of chemotherapy benefit, long-term impacts and changes in UK pre-/post-chemotherapy decisions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017059561.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Commercially Available Gene Expression Assays as Predictive Tools for Adjuvant Radiotherapy? A Critical Review

Background

Gene expression assays are increasingly used for decision-making regarding adjuvant chemotherapy in patients with hormone receptor-positive, HER2-negative breast cancer. There are some clinical situations in which there is also a need for better prognostic and predictive markers to better estimate the amount of benefit from adjuvant radiotherapy. The rising availability of gene expression analyses prompts the question whether their results can also be used to guide clinical decisions regarding adjuvant radiation.

Summary

Multiple studies suggest a correlation between results from gene expression assays and locoregional recurrence rates. Only few publications addressed the predictive value of results from gene expression analysis for the role of adjuvant radiotherapy in different settings.

Key Messages

To date, the available evidence on the possible predictive value of gene expression assays for radiotherapy does not support their inclusion into the decision-making process for adjuvant radiation. This is due to methodological weaknesses and limitations regarding patient selection, the nonrandomized design of all studies in terms of radiotherapy use, and limited availability of tissue from prospective trials. Thus, utilization of the present knowledge for clinical indication of radiotherapy should be very cautious.

Clinicogenomic Radiotherapy Classifier Predicting the Need for Intensified Locoregional Treatment After Breast-Conserving Surgery for Early-Stage Breast Cancer

PURPOSE

Most patients with early-stage breast cancer are treated with adjuvant radiotherapy (RT) after breast-conserving surgery (BCS) to prevent locoregional recurrence (LRR). However, no genomic tools are used currently to select the optimal RT strategy.

METHODS

We profiled the transcriptome of primary tumors on a clinical grade assay from the SweBCG91-RT trial, in which patients with node-negative breast cancer were randomly assigned to either whole-breast RT after BCS or no RT. We derived a new classifier, Adjuvant Radiotherapy Intensification Classifier (ARTIC), comprising 27 genes and patient age, in three publicly available cohorts, then independently validated ARTIC for LRR in 748 patients in SweBCG91-RT. We also compared previously published genomic signatures for ability to predict benefit from RT in SweBCG91-RT.

RESULTS

ARTIC was highly prognostic for LRR in patients treated with RT (hazard ratio [HR], 3.4; 95% CI, 2.0 to 5.9; P < .001) and predictive of RT benefit (P_interaction = .005). Patients with low ARTIC scores had a large benefit from RT (HR, 0.33 [95% CI, 0.21 to 0.52], P < .001; 10-year cumulative incidence of LRR, 6% v 21%), whereas those with high ARTIC scores benefited less from RT (HR, 0.73 [95% CI, 0.44 to 1.2], P = .23; 10-year cumulative incidence of LRR, 25% v 32%). In contrast, none of the eight previously published signatures were predictive of benefit from RT in SweBCG91-RT.

CONCLUSION

ARTIC identified women with a substantial benefit from RT as well as women with a particularly elevated LRR risk in whom whole-breast RT was not sufficiently effective and, thus, in whom intensified treatment strategies such as tumor-bed boost, and possibly regional nodal RT, should be considered. To our knowledge, ARTIC is the first classifier validated as predictive of benefit from RT in a phase III clinical trial with patients randomly assigned to receive or not receive RT.

Tailored axillary surgery with or without axillary lymph node dissection followed by radiotherapy in patients with clinically node-positive breast cancer (TAXIS): study protocol for a multicenter, randomized phase-III trial

Background

Complete lymph node removal through conventional axillary dissection (ALND) has been standard treatment for breast cancer patients for almost a century. In the 1990s, however, and in parallel with the advent of the sentinel lymph node (SLN) procedure, ALND came under increasing scrutiny due to its association with significant patient morbidity. Several studies have since provided evidence to suggest omission of ALND, often in favor of axillary radiation, in selected clinically node-negative, SLN-positive patients, thus supporting the current trend in clinical practice. Clinically node-positive patients, by contrast, continue to undergo ALND in many cases, if only for the lack of studies re-assessing the indication for ALND in these patients. Hence, there is a need for a clinical trial to evaluate the optimal treatment for clinically node-positive breast cancer patients in terms of surgery and radiotherapy. The TAXIS trial is designed to fill this gap by examining in particular the value of tailored axillary surgery (TAS), a new technique for selectively removing positive lymph nodes.

Methods

In this international, multicenter, phase-III, non-inferiority, randomized controlled trial (RCT), including 34 study sites from four different countries, we plan to randomize 1500 patients to either receive TAS followed by ALND and regional nodal irradiation excluding the dissected axilla, or receive TAS followed by regional nodal irradiation including the full axilla. All patients undergo adjuvant whole-breast irradiation after breast-conserving surgery and chest-wall irradiation after mastectomy. The main objective of the trial is to test the hypothesis that treatment with TAS and axillary radiotherapy is non-inferior to ALND in terms of disease-free survival of clinically node-positive breast cancer patients in the era of effective systemic therapy and extended regional nodal irradiation. The trial was activated on 31 July 2018 and the first patient was randomized on 7 August 2018.

Discussion

Designed to test the hypothesis that TAS is non-inferior to ALND in terms of curing patients and preventing recurrences, yet is significantly superior in reducing patient morbidity, this trial may establish a new worldwide treatment standard in breast cancer surgery. If found to be non-inferior to standard treatment, TAS may significantly contribute to reduce morbidity in breast cancer patients by avoiding surgical overtreatment.

Trial registration

ClinicalTrials.gov, ID: NCT03513614. Registered on 1 May 2018.

www.kofam.ch, ID: NCT03513614. Registered on 17 June 2018.

EudraCT No.: 2018–000372-14.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3021-9) contains supplementary material, which is available to authorized users.

Mammaprint™: a comprehensive review

The number of breast cancer (BC) cases is growing worldwide, being most frequently diagnosed in the early-setting. Mammaprint™ is a 70-gene-expression signature, originally designed for selecting early BC patients with low risk of developing metastasis, so that they could be spared adjuvant chemotherapy. Its use as a prognostic biomarker has been extensively validated, both retrospectively and prospectively. However, its value as a predictive tool and as a clinically useful tool remains controversial. This review will describe how the test works, its application in the clinic and its limitations. Cost-effectiveness studies will be summarized. Finally, we will provide a perspective on the use of Mammaprint in the near future, as a valuable tool for personalizing the treatment of early BC patients.

Microenvironmental Signals and Biochemical Information Processing: Cooperative Determinants of Intratumoral Plasticity and Heterogeneity

Intra-tumor cellular heterogeneity is a major challenge in cancer therapy. Tumors are composed of multiple phenotypic subpopulations that vary in their ability to initiate metastatic tumors and in their sensitivity to chemotherapy. In many cases, cells can transition between these subpopulations, not by genetic mutation, but instead through reversible changes in signal transduction or gene expression programs. This plasticity begins at the level of the microenvironment where local autocrine and paracrine signals, exosomes, tumor–stroma interactions, and extracellular matrix (ECM) composition create a signaling landscape that varies over space and time. The integration of this complex array of signals engages signaling pathways that control gene expression. The resulting modulation of gene expression programs causes individual cells to sample a wide array of phenotypic states that support tumor growth, dissemination, and therapeutic resistance. In this review, we discuss how information flows dynamically within the microenvironmental landscape to inform cell state decisions and to create intra-tumoral heterogeneity. We address the role of plasticity in the acquisition of transient and prolonged drug resistant states and discuss how targeted pharmacological modification of the signaling landscape may be able to constrain phenotypic plasticity, leading to improved treatment responses.

Efficacy of single-stage breast-conserving treatment using multicatheter partial breast brachytherapy evaluated by GEC-ESTRO phase 3 trial

Purpose

The GEC-ESTRO has reported the equivalent outcomes of partial breast irradiation (PBI) using multicatheter interstitial brachytherapy (MCB) to whole breast irradiation (WBI) in breast-conserving therapy (BCT). We performed single-stage BCT with partial breast brachytherapy by intraoperative catheter placement. After the categorization of patients into inclusion and exclusion criteria on this trial, our databases were evaluated in order to translate it to Japanese patients.

Material and methods

Patients undergoing BCT were retrospectively examined between November 2007 and December 2015. The technique is an open-cavity implant with a dose of 32 Gy in 8 fractions. The 4-year clinical outcomes of MCB-PBI were evaluated in the 2 distinct categories, and the comparison of the outcomes of MCB-PBI with WBI was performed in patients with unfavorable features.

Results

Of a total of 501 lesions undergoing BCT, 301 lesions were treated with MCB-PBI and 200 lesions with WBI. At the median follow-up time of 52 months, the 4-year rate of ipsilateral breast tumor recurrence (IBTR)-free, disease-free (DFS), and overall survival (OS) in patients with MCB-PBI and WBI were 98.9% vs. 98.0% (p = 0.56), 97.0% vs. 95.3% (p = 0.78), and 99.6% vs. 98.2% (p = 0.38), respectively. Although in exclusion cohort treated with MCB-PBI, IBTR-free, and disease-free survival were significantly worse than in inclusion cohort, non-significantly worse outcomes was demonstrated than in exclusion cohort with WBI; IBTR-free survival (95.0% vs. 97.2%, p = 0.24), and disease-free survival (95.0% vs. 95.8%, p = 0.31).

Conclusions

Single-stage BCT using MCB-PBI offered similar tumor control rates compering to WBI. However, further research is needed to define the benefit for patients with an exclusion criteria.

Systematic review of the clinical and economic value of gene expression profiles for invasive early breast cancer available in Europe

Gene expression profiles with prognostic capacities have shown good performance in multiple clinical trials. However, with multiple assays available and numerous types of validation studies performed, the added value for daily clinical practice is still unclear. In Europe, the MammaPrint, OncotypeDX, PAM50/Prosigna and Endopredict assays are commercially available. In this systematic review, we aim to assess these assays on four important criteria: Assay development and methodology, clinical validation, clinical utility and economic value. We performed a literature search covering PubMed, Embase, Web of Science and Cochrane, for studies related to one or more of the four selected assays. We identified 147 papers for inclusion in this review. MammaPrint and OncotypeDX both have evidence available, including level IA clinical trial results for both assays. Both assays provide prognostic information. Predictive value has only been shown for OncotypeDX. In the clinical utility studies, a higher reduction in chemotherapy was achieved by OncotypeDX, although the number of available studies differ considerably between tests. On average, economic evaluations estimate that genomic testing results in a moderate increase in total costs, but that these costs are acceptable in relation to the expected improved patient outcome. PAM50/prosigna and EndoPredict showed comparable prognostic capacities, but with less economical and clinical utility studies. Furthermore, for these assays no level IA trial data are available yet. In summary, all assays have shown excellent prognostic capacities. The differences in the quantity and quality of evidence are discussed. Future studies shall focus on the selection of appropriate subgroups for testing and long-term outcome of validation trials, in order to determine the place of these assays in daily clinical practice.

Comparison of variable selection methods for high-dimensional survival data with competing events

BACKGROUND

In the era of personalized medicine, it's primordial to identify gene signatures for each event type in the context of competing risks in order to improve risk stratification and treatment strategy. Until recently, little attention was paid to the performance of high-dimensional selection in deriving molecular signatures in this context. In this paper, we investigate the performance of two selection methods developed in the framework of high-dimensional data and competing risks: Random survival forest and a boosting approach for fitting proportional subdistribution hazards models.

METHODS

Using data from bladder cancer patients (GSE5479) and simulated datasets, stability and prognosis performance of the two methods were evaluated using a resampling strategy. For each sample, the data set was split into 100 training and validation sets. Molecular signatures were developed in the training sets by the two selection methods and then applied on the corresponding validation sets.

RESULTS

Random survival forest and boosting approach have comparable performance for the prediction of survival data, with few selected genes in common. Nevertheless, many different sets of genes are identified by the resampling approach, with a very small frequency of genes occurrence among the signatures. Also, the smaller the training sample size, the lower is the stability of the signatures.

CONCLUSION

Random survival forest and boosting approach give good predictive performance but gene signatures are very unstable. Further works are needed to propose adequate strategies for the analysis of high-dimensional data in the context of competing risks.

Prognostic assessment and systemic treatments of invasive local relapses of hormone receptor-positive breast cancer

The rate of local recurrences, after breast-conserving surgery or mastectomy for hormone receptor-positive (HR+) breast cancer, has dramatically changed in last decades, due to advances in surgical and radiation techniques and a more extensive use of adjuvant systemic treatments. However, the occurrence of local recurrences remains a major predictor for distant metastasis and is responsible for increased cancer-specific death. It has been estimated that 1 in 4 HR+ and HR-ipsilateral breast recurrences leads to widespread metastatic disease, with an annual mortality rate of 10% in the first 5 years. Nevertheless, very few studies have been conducted to evaluate the optimal care of purely HR+ local relapses of breast cancer, after surgical removal. In this review we have highlighted the available knowledge on prognostic assessment and systemic treatment for women experiencing local relapses of HR+ breast cancers, underlying unsolved questions and controversial clinical aspects.

Clinical utility of gene-expression signatures in early stage breast cancer

Breast cancer is a heterogeneous disease, with different subtypes having a distinct biological, molecular, and clinical course. Assessments of standard clinical and pathological features have traditionally been used to determine the use of adjuvant systemic therapy in patients with early stage breast cancer; however, the ability to identify those who will benefit from adjuvant chemotherapy remains a challenge, leading to the overtreatment of some patients. Advances in molecular medicine have substantially improved the accuracy of gene-expression profiling of breast tumours, resulting in improvements in the ability to predict a patient's risk of breast cancer recurrence and likely response to endocrine therapy and/or chemotherapy. These genomic assays, several of which are commercially available, have aided physicians in tailoring treatment decisions for patients at the individual level. Herein, we describe the available data on the clinical validity of the most widely available assays in patients with early stage breast cancer, with a focus on the development, validation, and clinical application of these assays, in addition to the anticipated outcomes of ongoing prospective trials. We also review data from comparative studies of these assays and from cost-effectiveness analyses relating to their clinical use.

Individualized Breast Cancer Characterization through Single-Cell Analysis of Tumor and Adjacent Normal Cells

There is a need to individualize assays for tumor molecular phenotyping, given variations in the differentiation status of tumor and normal tissues in different patients. To address this, we performed single-cell genomics of breast tumors and adjacent normal cells propagated for a short duration under growth conditions that enable epithelial reprogramming. Cells analyzed were either unselected for a specific subpopulation or phenotypically defined as undifferentiated and highly clonogenic ALDH⁺/CD49f⁺/EpCAM⁺ luminal progenitors, which express both basal cell and luminal cell-enriched genes. We analyzed 420 tumor cells and 284 adjacent normal cells for expression of 93 genes that included a PAM50-intrinsic subtype classifier and stemness-related genes. ALDH⁺/CD49f⁺/EpCAM⁺ tumor and normal cells clustered differently compared with unselected tumor and normal cells. PAM50 gene-set analyses of ALDH⁺/CD49f⁺/EpCAM⁺ populations efficiently identified major and minor clones of tumor cells, with the major clone resembling clinical parameters of the tumor. Similarly, a stemness-associated gene set identified clones with divergent stemness pathway activation within the same tumor. This refined expression profiling technique distinguished genes truly deregulated in cancer from genes that identify cellular precursors of tumors. Collectively, the assays presented here enable more precise identification of cancer-deregulated genes, allow for early identification of therapeutically targetable tumor cell subpopulations, and ultimately provide a refinement of precision therapeutics for cancer treatment. Cancer Res; 77(10); 2759-69. ©2017 AACR.

Prognostic Impact of Elective Supraclavicular Nodal Irradiation for Patients with N1 Breast Cancer after Lumpectomy and Anthracycline Plus Taxane-Based Chemotherapy (KROG 1418): A Multicenter Case-Controlled Study

Purpose

This study was conducted to evaluate the impact of supraclavicular lymph node radiotherapy (SCNRT) on N1 breast cancer patients receiving post-lumpectomy whole-breast irradiation (WBI) and anthracycline plus taxane-based (AT) chemotherapy.

Materials and Methods

We performed a case-control analysis to compare the outcomes of WBI and WBI plus SCNRT (WBI+SCNRT). Among 1,147 patients with N1 breast cancer who received post-lumpectomy radiotherapy and AT-based chemotherapy in 12 hospitals, 542 were selected after propensity score matching. Patterns of failure, disease-free survival (DFS), distant metastasis-free survival (DMFS), and treatment-related toxicity were compared between groups.

Results

A total of 41 patients (7.6%) were found to have recurrence. Supraclavicular lymph node (SCN) failure was detected in three patients, two in WBI and one in WBI+SCNRT. All SCN failures were found simultaneously with distant metastasis. There was no significant difference in patterns of failure or survival between groups. The 5-year DFS and DMFS for patients with WBI and WBI+SCNRT were 94.4% versus 92.6% (p=0.50) and 95.1% versus 94.5% (p=0.99), respectively. The rates of lymphedema and radiation pneumonitis were significantly higher in the WBI+SCNRT than in the WBI.

Conclusion

We did not find a benefit of SCNRT for N1 breast cancer patients receiving AT-based chemotherapy.

The changing landscape in radiotherapy for breast cancer: Lessons from long term follow-up in some European breast cancer trials

This review describes the developments in the radiation treatment of breast cancer based on some randomized European trials during the past decades. It will focus on the relevance of long term follow-up in breast cancer patients, starting with the surprising and important change in treatment results during follow-up shown in a locally advanced breast cancer trial. Breast conserving therapy (BCT) in stage I and II breast cancer was explored and tested in a randomized trial to prove equivalence between BCT and mastectomy. The positive outcome led to trials in breast conserving therapy with lower doses and partial breast irradiation. Finally the need for finding genetic profiles for predicting treatment response will be addressed in a trial with preoperative partial breast irradiation.

Low risk of recurrence in elderly patients treated with breast conserving therapy in a single institute

OBJECTIVES

To guide decision making in preventing over- or under-treatment in older breast cancer patients who have undergone breast conserving surgery, we analyzed prognostic factors and risk of recurrence in a consecutive series of patients ≥ 65 years old with breast cancer and identified subgroups that may benefit or not from more intensive treatment.

METHODS

Patients ≥65 years of age with breast cancer (pT1-2/pN0-2) treated with breast conserving surgery and postoperative radiation therapy at the Netherlands Cancer Institute (NKI) between 1980 and 2008 were identified. Endpoints were locoregional recurrence (LRR), distant metastasis (DM) and overall survival (OS). Multivariable analyses were performed using Cox proportional hazards models.

RESULTS

1922 patients with a median age of 70 years were analyzed. The 5- and 10- years LRR rates were 2% and 3% respectively. In multivariable analysis there was no significant factor influencing LRR risk. Patients with low risk tumors (node negative patients with T1 and ER positive, grade 1 or 2) had lower risk of DM (HR 0.26) and better OS (HR 0.65) compared to patients with higher risk tumors (grade 3 and/or node positive).

CONCLUSION

In elderly breast cancer patients the risk of LRR and DM is low. In patients with less favorable characteristics the risk of LRR is equally low, with a higher risk to develop DM and worse OS. Treatment in the low risk group may be minimized, while for the higher risk group adjuvant treatment could be intensified.

Biomarkers of Tumour Radiosensitivity and Predicting Benefit from Radiotherapy

Radiotherapy is an essential component of treatment for more than half of newly diagnosed cancer patients. The response to radiotherapy varies widely between individuals and although advances in technology have allowed the adaptation of radiotherapy fields to tumour anatomy, it is still not possible to tailor radiotherapy based on tumour biology. A biomarker of intrinsic radiosensitivity would be extremely valuable for individual dosing, aiding decision making between radical treatment options and avoiding toxicity of neoadjuvant or adjuvant radiotherapy in those unlikely to benefit. This systematic review summarises the current evidence for biomarkers under investigation as predictors of radiotherapy benefit. Only 10 biomarkers were identified as having been evaluated for their radiotherapy-specific predictive value in over 100 patients in a clinical setting, highlighting that despite a rich literature there were few high-quality studies for inclusion. The most extensively studied radiotherapy predictive biomarkers were the radiosensitivity index and MRE11; however, neither has been evaluated in a randomised controlled trial. Although these biomarkers show promise, there is not enough evidence to justify their use in routine practice. Further validation is needed before biomarkers can fulfil their potential and predict treatment outcomes for large numbers of patients.

Independent replication of a melanoma subtype gene signature and evaluation of its prognostic value and biological correlates in a population cohort

Development and validation of robust molecular biomarkers has so far been limited in melanoma research. In this paper we used a large population-based cohort to replicate two published gene signatures for melanoma classification. We assessed the signatures prognostic value and explored their biological significance by correlating them with factors known to be associated with survival (vitamin D) or etiological routes (nevi, sun sensitivity and telomere length). Genomewide microarray gene expressions were profiled in 300 archived tumors (224 primaries, 76 secondaries). The two gene signatures classified up to 96% of our samples and showed strong correlation with melanoma specific survival (P=3 x 10(-4)), Breslow thickness (P=5 x 10(-10)), ulceration (P=9.x10-8) and mitotic rate (P=3 x 10(-7)), adding prognostic value over AJCC stage (adjusted hazard ratio 1.79, 95%CI 1.13-2.83), as previously reported. Furthermore, molecular subtypes were associated with season-adjusted serum vitamin D at diagnosis (P=0.04) and genetically predicted telomere length (P=0.03). Specifically, molecular high-grade tumors were more frequent in patients with lower vitamin D levels whereas high immune tumors came from patients with predicted shorter telomeres. Our data confirm the utility of molecular biomarkers in melanoma prognostic estimation using tiny archived specimens and shed light on biological mechanisms likely to impact on cancer initiation and progression.

Cell cycle arrest and induction of apoptosis by cajanin stilbene acid from Cajanus cajan in breast cancer cells

BACKGROUND

The low abundant cajanin stilbene acid (CSA) from Pigeon Pea (Cajanus cajan) has been shown to kill estrogen receptor α positive cancer cells in vitro and in vivo. Downstream effects such as cell cycle and apoptosis-related mechanisms have not been analyzed yet.

MATERIAL AND METHODS

We analyzed the activity of CSA by means of flow cytometry (cell cycle distribution, mitochondrial membrane potential, MMP), confocal laser scanning microscopy (MMP), DNA fragmentation assay (apoptosis), Western blotting (Bax and Bcl-2 expression, caspase-3 activation) as well as mRNA microarray hybridization and Ingenuity pathway analysis.

RESULTS

CSA induced G2/M arrest and apoptosis in a concentration-dependent manner from 8.88 to 14.79 µM. The MMP broke down, Bax was upregulated, Bcl-2 downregulated and caspase-3 activated. Microarray profiling revealed that CSA affected BRCA-related DNA damage response and cell cycle-regulated chromosomal replication pathways.

CONCLUSION

CSA inhibited breast cancer cells by DNA damage and cell cycle-related signaling pathways leading to cell cycle arrest and apoptosis.