(BPT) - A breast cancer diagnosis often brings tough questions: What's the right treatment for me? How long should I stay on medication? Will the side effects be worth it?

Today, genomic testing is giving women and their providers new tools to make more confident, personalized treatment decisions-especially when it comes to long-term hormone therapy (also called endocrine therapy) for early-stage breast cancer.

Understanding Hormone-Driven Breast Cancer

Many breast cancers are fueled by hormones like estrogen or progesterone. These are called hormone receptor-positive cancers, and they are often treated with endocrine therapy-medications that block or lower hormone levels to help prevent the cancer from coming back. Hormone therapy may be given as a pill, injection, or both.

The standard duration for hormone therapy is five years¹, but in some cases, doctors may recommend continuing treatment for up to ten years. This is called extended hormone therapy, and the decision to go beyond five years depends on the individual's risk of recurrence.

While hormone therapy is effective, it often comes with side effects-such as joint pain, hot flashes, fatigue, and mood changes-that can significantly affect a person's quality of life. In fact, around 80% of women on hormone therapy report experiencing side effects², which can lead to missed doses, early discontinuation, or outright refusal to continue or extend treatment. These challenges make it even more important to identify who truly benefits from extended therapy and who may not need it.

By knowing the optimal duration of therapy for each individual, care teams can ensure patients are receiving the benefit of treatment without unnecessary exposure to years of side effects-striking the right balance between reducing recurrence risk and quality of life.

How Genomic Testing Can Help

That's where genomic tests like MammaPrint^® and BluePrint^® come in. Together, these tests analyze the activity of specific genes in a breast cancer tumor to reveal how the cancer is likely to behave. This information helps doctors personalize multiple treatment recommendations from the beginning.

• MammaPrint looks at 70 genes to assess a tumor's risk of recurrence. Studies have shown it can help inform a range of treatment decisions-such as identifying women who may safely avoid extended hormone therapy and those who may benefit from continuing.^3,4
• BluePrint evaluates 80 genes to determine the tumor's molecular subtype, providing deeper insight into how the cancer may respond to different treatments.⁵

With results available within days, these tests provide valuable answers early-sometimes even before surgery-so treatment planning can begin right away.

Personalized Care for the Long Haul

For women with MammaPrint High Risk tumors, studies show that extended hormone therapy beyond five years isn't necessary, sparing them additional years of side effects.^3-4 For others, like those with MammaPrint Low Risk, it can reinforce the importance of staying the course-knowing extended treatment significantly reduces their risk of recurrence.^3-4 For women with MammaPrint UltraLow, studies show that tumors may have the option to safely reduce their standard treatment duration based on their exceptionally low recurrence risk.²

Genomic testing doesn't just guide medication choices-it supports peace of mind. When women understand the "why" behind their treatment plan, they're more likely to stay with it.

Backed by Research, Built for Everyone

These personalized treatment options are supported by landmark clinical trials-including the Stockholm Tamoxifen Trial (STO-3),² NSABP B-42,³ and IDEAL⁴-which show that patients with different MammaPrint risk classifications benefit from different durations of hormone therapy. These studies provide critical evidence that not all patients require extended treatment, and that tailoring therapy duration based on genomic risk can help reduce over-treatment while maintaining strong outcomes. As genomic testing becomes a standard part of care, women and their doctors can work together to create treatment plans that are not just effective-but also personalized, evidence-based, and empowering.

Learn more at Agendia.com.

1. NCCN. Breast Cancer. Version 3.2024. JNCCN. 2024;22(5):331-357.
2. Rosso R et al. Curr Oncol. 2023;30(2):1461-72.
3. Rastogi P et al. J Clin Oncol. 2024;00:1-9.
4. van 't Veer LJ, et al. JAMA. November 2024
5. Whitworth, P., et al. Ann Surg Oncol (2022) 29:4141-4152