MammaPrint in personalization of treatment

• MammaPrint test results enable oncologists to provide more precise treatments, reduce toxicity, and better manage healthcare resources to improve patients’ quality of life.

• New research published in Journal of Clinical Oncology concludes that patients classified as low risk by this genomic platform benefit from adding advanced endocrine therapy to their treatment.

Currently, one of the biggest challenges in breast cancer treatment is determining which patients can benefit from each of the different treatments without incurring unnecessary toxicity. In this sense, the MammaPrint genomic test allows oncologists to select more precise treatments and help them make clinical decisions to improve outcomes for patients with early breast cancer.

To do this, the platform analyzes 70 tumor genes and classifies them into categories of high or low risk of recurrence. The tool goes beyond traditional clinical risk assessment by incorporating in-depth analysis of a tumor’s genetic profile to more accurately predict the potential benefit of treatment.

New research on personalizing patient treatment using the MammaPrint platform

Recent NSABP B-42 Studypublished in Journal of Clinical Oncologyhelped to clarify which subgroups of patients would benefit from extended treatment with endocrine therapy and which would not. According to the results, extended treatment with letrozole is beneficial for patients with breast cancer classified as low risk by the MammaPrint platform, but not for those classified as high risk or ultra-low risk.

Letrozole is a hormonal treatment that lowers estrogen levels in the body, which helps slow the growth of hormone-sensitive tumors. Although its side effects are less severe than those of chemotherapy, it also negatively affects a woman’s quality of life. Its symptoms may be similar to those of menopause, including but not limited to joint and muscle pain, nausea, or osteoporosis.

According to various experts, these hormonal treatments do not cause serious side effects, but they do cause very unpleasant and long-lasting side effects. Thus, the fact that the patient receives this treatment at the most appropriate time significantly improves her quality of life. Thanks to retrospective studies, we know that those patients found to be ultra-low risk in the MammaPrint analysis may require as little as two years of treatment, high-risk patients may require 5 years, and low-risk (not ultra-low) patients with node-negative or large tumors may require from 7 to 10 years of treatment.

Having reliable information about which women can avoid these treatments and which women benefit allows oncologists to provide more precise treatments, reduce toxicity, and better manage healthcare resources. This is not only about prolonging the lives of patients, but also about improving the quality of life by minimizing unnecessary treatment and its side effects.

In the study, patients with tumors classified as low risk showed significant benefit from extended letrozole therapy. The 10-year benefit was important for these patients’ disease-free survival, which increased by 7.8%, as well as their breast cancer-free interval, which increased by 7.0%.

In contrast, patients with high-risk tumors showed no significant benefit from extended therapy, nor did patients with tumors classified as ultra-low-risk, highlighting the importance of careful patient selection to avoid unnecessary treatment and associated secondary effects. Integrating these types of genomic tools into routine clinical practice is changing the approach to breast cancer treatment.

Scientific article: Rastogi P, et al: Utility of the 70-gene MammaPrint assay for predicting benefit from extended letrozole therapy in the NRG Oncology/NSABP B-42 trial. J Clin Oncol. July 24, 2024: JCO2301995. doi: https://doi.org/10.1200/jco.23.01995

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