Genomic Test Spares Cancer Patients Chemotherapy

Breast cancer tumor testing for its genomic signature can help identify which patients will need adjuvant systemic therapy, and/or additional chemotherapy, after surgery.

By looking for a particular selection of genes in a tumor, doctors can predict the patients at low or high risk of metastasis, which enables doctors to select those patients that could be spared the side effects of chemotherapy without adversely affecting their chances of disease-free survival.

Scientists at the Netherlands Cancer Institute, (Amsterdam, The Netherlands) studied follow-up data from 427 patients with early breast cancer who had taken part in a study called Microarray prognostics in breast cancer (RASTER). Their cancers had not yet spread to the lymph nodes and were therefore denoted node-negative. The team looked for a particular selection of 70 genes in a tumor using the Mammaprint test. In addition to the results of the test, the researchers also used the web-based risk-prediction tool Adjuvant! Online (AOL) in order to obtain a prognosis. The study aimed to assess the feasibility of implementing the test in daily clinical practice in The Netherlands, as well as its effect on adjuvant systemic treatment decisions.

Initially the test had to be carried out on fresh frozen tumor tissue, which involved complicated and expensive logistics. However, since January 2012, technical advances have meant that it is now possible to use formalin-fixed, paraffin-embedded tissue, the standard way to store tumor tissue, which will enhance the availability of the test considerably. The scientists now intend to study two further genomic tests to see whether they can further refine prognosis in the same group of breast cancer patients.

In the group classified as low risk by the Mammaprint test (Agendia; Irvine, CA, USA) only 15% of the 219 patients received adjuvant chemotherapy as opposed to 81% (169/208) in the group classified as high risk by the Mammaprint test. The first group had a five-year distant disease-free survival (DDFS) rate of 96% compared with 90% in the high-risk group. In the groups where the Mammaprint and AOL (Anaheim, CA, USA) results were discordant, where the genomic test predicted a low risk and AOL a high risk, 43% of patients received endocrine therapy and 24% chemotherapy. There was a 98% DDFS in this group. Where AOL predicted a low risk but Mammaprint a high one, 78% received endocrine therapy and 57% chemotherapy. The DDFS in this group was 95%.

Sabine C. Linn, MD, PhD, and lead author of the study, said, "Based on our data, the use of the genomic test could lead to a reduction of nearly 30% in the use of adjuvant chemotherapy without compromising patient outcomes. This percentage may vary somewhat due to different guidelines used in different countries. These findings are important both for quality of life and for cutting down unnecessary healthcare costs." The study was presented at the 8th European Breast Cancer Conference (EBCC-8), held in Vienna (Austria) from March 21-24, 2012.

Related Links:
Netherlands Cancer Institute
Agendia
Adjuvant! Online