Abstract

The 70-gene signature (MammaPrint™) has been developed on retrospective series of breast cancer patients to predict the risk of breast cancer distant metastases. The microarRAy-prognoSTics-in-breast-cancER (RASTER) study was the first study designed to prospectively evaluate the performance of the 70-gene signature, which result was available for 427 patients (cT1–3N0M0). Adjuvant systemic treatment decisions were based on the Dutch CBO 2004 guidelines, the 70-gene signature and doctors' and patients' preferences. Five-year distant-recurrence-free-interval (DRFI) probabilities were compared between subgroups based on the 70-gene signature and Adjuvant! Online (AOL) (10-year survival probability <90% was defined as high-risk). Median follow-up was 61.6 months. Fifteen percent (33/219) of the 70-gene signature low-risk patients received adjuvant chemotherapy (ACT) versus 81% (169/208) of the 70-gene signature high-risk patients. The 5-year DRFI probabilities for 70-gene signature low-risk (n = 219) and high-risk (n = 208) patients were 97.0% and 91.7%. The 5-year DRFI probabilities for AOL low-risk (n = 132) and high-risk (n = 295) patients were 96.7% and 93.4%. For 70-gene signature low-risk–AOL high-risk patients (n = 124), of whom 76% (n = 94) had not received ACT, 5-year DRFI was 98.4%. In the AOL high-risk group, 32% (94/295) less patients would be eligible to receive ACT if the 70-gene signature was used. In this prospective community-based observational study, the 5-year DRFI probabilities confirmed the additional prognostic value of the 70-gene signature to clinicopathological risk estimations such as AOL. Omission of adjuvant chemotherapy as judged appropriate by doctors and patients and instigated by a low-risk 70-gene signature result, appeared not to compromise outcome.

Highlights

  • Over the last two decades breast cancer mortality has declined in Western countries

  • adjuvant systemic therapy (AST) and outcome stratified by 70-gene signature Supporting Information Table 1 summarizes the patient characteristics defined by the result of the 70-gene signature as reported by Bueno-de-Mesquita et al.6 70-gene signature high-risk patients more often had large, poorly differentiated, estrogen receptor (ER) negative, progesterone receptor (PR) negative and HER2 positive tumors than 70-gene signature low-risk patients

  • The RASTER study provides the first prospective data on the outcome of patients with breast cancer for whom a gene expression prognosis classifier was used to determine the need for adjuvant systemic treatment

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Summary

Introduction

Over the last two decades breast cancer mortality has declined in Western countries. This decline has been ascribed to early detection due to the implementation of population-based mammographic screening programs and the introduction of adjuvant systemic therapy (AST).[1]. The microarRAy prognoSTics in breast cancER (RASTER) study was conducted in 16 community hospitals in the Netherlands.[6] The primary aim of this multicenter observational study was to assess the feasibility of implementing the 70-gene signature in a community-based setting and to study the clinical impact of the 70-gene signature test result on AST decision making.[6] A secondary aim of the RASTER study was to assess the outcome of patients for whom a gene expression classifier was used to determine the need for adjuvant systemic treatment. A considerable discrepancy in risk estimations among different clinicopathological guidelines and the 70-gene signature was observed.[6] The addition of the 70-gene signature test result to standard clinicopathological factors led to a change in AST advice in 19% of patients.[6] Here, we report the 5-year follow-up data of the RASTER study

Methods
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Conclusion

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