Predictive vs prognostic breast cancer testing
What Does Your Breast Cancer Genomic Test Really Tell You— and Why MammaPrint’s Latest Data Matters?

 
If you or someone you love has been diagnosed with early-stage breast cancer, especially HR-positive/ HER2-negative breast cancer, you’ve likely come across genomic tests like MammaPrint. At a time when everything can feel overwhelming, these tests can provide something incredibly powerful: clarity.

But what do these test results really tell you? And when your doctor mentions words like prognostic or predictive, what does that mean—and why should you care?

It turns out, understanding these two terms may make all the difference in your treatment journey—especially when it comes to deciding whether chemotherapy is truly necessary for you.

Thanks to a recent publication in JNCI Cancer Spectrum using real-world data from the FLEX study, we now have robust evidence that MammaPrint not only estimates risk of recurrence (prognostic) but also predicts who is likely to benefit from chemotherapy (predictive). This is an important advancement for precision oncology and for patient-centered care.

Let’s take a moment to unpack what predictive and prognostic mean—and why this new evidence matters.

What Are Genomic Tests?

Genomic tests like MammaPrint analyze the activity of genes in your breast tumor, not your inherited DNA (which is what genetic tests like BRCA1/2 assess). The purpose of a genomic test is to help determine:

  • How likely the cancer is to come back (recurrence risk or risk of relapse)
  • Whether certain treatments, like chemotherapy, are likely to help

This information supports shared, informed, evidence-based decision-making between patients and clinicians.

Prognostic vs. Predictive: What’s the Difference?

Prognostic

This tells your doctor how the cancer might behave over time—if left untreated beyond basic hormone therapy. It helps estimate things like:

  • How likely is the cancer to come back?
  • Is this a slow-growing or aggressive tumor?

In short: it answers “What might happen if I don’t get chemotherapy?”

Predictive tests go a step further: they tell us whether a specific treatment, like chemotherapy, is likely to provide benefit. 

  • Will chemotherapy significantly reduce my risk of recurrence?
  • Will it improve outcomes beyond what hormone therapy alone can achieve?

Both types of information matter. But not every genomic test provides both. That’s where MammaPrint’s latest data changes the conversation.

What’s New: MammaPrint Does Both—And That’s a Big Deal

In the recently published FLEX real-world evidence in JNCI Cancer Spectrum, we now know that MammaPrint is both prognostic and predictive. This is a critical finding—because most patients fall into the clinically high-risk category, and clinicians often face uncertainty when determining whether chemotherapy adds value to endocrine therapy alone.

Key findings from the publication:

  • MammaPrint identified a subgroup of patients with high genomic risk who derived a clear clinical benefit from chemotherapy.
  • Conversely, patients with low genomic risk scores showed no additional benefit from chemo— supporting the safe use of endocrine therapy alone in many cases.
  • These results reflect real-world clinical practice across diverse care settings, further validating the test’s utility outside of controlled trials.
  • This evidence establishes MammaPrint as both prognostic and predictive, giving oncologists a full picture of patients’ tumor when personalizing treatment.

Why This Matters for Patients and Clinicians

Every person’s cancer is different. What works for one patient might not be necessary—or helpful—for another. That’s why knowing whether your test is prognostic, predictive, or both matters.

With tests like MammaPrint testing, you and your doctor can:

  • Avoid chemotherapy if it’s unlikely to help—sparing you the physical, emotional, and financial burden
  • Feel confident in choosing chemotherapy if it offers a clear benefit
  • Make informed, evidence-based choices that align with your values and goals

What to Ask Your Doctor

When you’re reviewing your test results, here are a few questions to consider:

  • Does this test tell me my risk of recurrence?
  • Does it also tell us whether chemotherapy will help reduce that risk?
  • How does this result influence the treatment plan we’re building together?

These questions aren’t just helpful—they’re empowering. And with tools like MammaPrint, your doctor has meaningful answers backed by solid scientific evidence.

Conclusions

You are more than your diagnosis—and more than just a number on a lab report. Your cancer is unique, and your treatment should be, too.

Thanks to genomic testing MammaPrint and the latest insights from the FLEX study, you now have access to information that’s both prognostic and predictive– giving you and your care team the confidence to make the best possible decisions, for you. Let’s simplify it: 

Prognostic = What might happen if I don’t get chemo? Vs Predictive = Will chemo help me personally? 

MammaPrint offers both. Because smarter treatment isn’t always stronger treatment—it’s the one that fits you best!