Genomic testing can help personalize your breast cancer treatment plan by helping map a path ahead. When navigating a breast cancer diagnosis, it can feel like approaching one fork in the road after another. What treatments will I need? Will I need chemotherapy? What is right for me?

Genomic testing, which could also be called tumor profiling, molecular profiling or signature testing, is one avenue that may offer answers to help give clarity at these crossroads. This Know More piece discusses how this type of testing works and how it can help tailor your treatment to you, making the road ahead more straightforward.

What is genomic testing and how is it different from genetic testing?

Genomic testing examines the activity of specific genes in the tumor including genes that influence how the cancer may grow, spread or come back later, also known as recurrence. This is different from genetic testing, which looks at the DNA you were born with. Think of it as genomic testing looks at the genes of the cancer while genetic testing looks at the genes of a person. While genetic testing examines the inherited changes in your DNA (like BRCA1 or BRCA2 mutations), which can increase your personal risk of cancer; genomic testing

reveals more information about your specific cancer, which may help guide the best way to treat it.

Both types of testing can be helpful, but they answer different questions and are used at different points in your care.

Who is Genomic Testing for?

Before genomic testing is considered, your care team will first learn about some key characteristics of your tumor to determine:

• Hormone receptor status

• HER2 status

• Tumor size and grade

• Lymph node involvement

These results come from your initial biopsy and pathology report. If your cancer’s profile meets certain criteria, genomic testing might be the next step. Ideally, it’s done before starting treatments like chemotherapy and before surgery is scheduled, so that your oncologist can use the results to help decide whether those treatments are truly necessary or likely to be beneficial. In most cases, these tests are performed on your tissue removed during your biopsy or during surgery but before any further therapies begin. Genomic testing is most commonly used for people diagnosed with hormone receptor-positive (HR+), HER2-negative (HER2-), early-stage breast cancer and for those with limited lymph node involvement, meaning it hasn’t spread much, or at all to the lymphatic system.

How are Genomic Tests for Breast Cancer Different?

There are different genomic tests available for breast cancer. Each test has its own strengths, and your doctor will recommend the one that best fits your unique situation. To choose a test that’s right for you, your doctor may take features of your breast cancer and your menopausal status into account. These tests look at different sets of genes but ultimately provide information about the likelihood of the cancer returning. People with breast cancer and their doctors can use this information to guide treatment decisions, like whether they will benefit from chemotherapy or extending hormone therapy beyond five years. The table below lists the most common genomic tests used for breast cancer. Again, your oncologist can recommend the test best suited to your specific diagnosis.

The field of genomic testing is evolving rapidly, and researchers are testing new applications for them. For example, new research on the MammaPrint test has suggested it may also be used to predict the benefit of extended hormone therapy in addition to helping with decisions about chemotherapy. There are also new tests being studied to help with treatment decisions for ductal carcinoma in situ (DCIS), HER2-positive breast cancer and triple negative breast cancer.

So, How Does Genomic Testing Help Map Your Treatment Plan?

Every individual’s breast cancer path is different – with many forks in the road. Genomic testing can help make it easier to draw your personal map. These tests can help you make informed treatment decisions, together with your doctor, that may improve your quality of life and help give you confidence in your treatment choices.

The Power of Personalized Care

Breast cancer care is most effective when it’s as individualized as you are. A clear path forward should reflect not only the specific biology of the tumor, but also your overall health and what matters most to you. Genomic testing can serve as a compass, helping your care team recommend treatments that are right for you while avoiding those that aren’t – all the while, potentially reducing side effects, visits to care centers and financial impact. The best way to know if genomic testing should be part of your experience is to talk with your doctor. Ask how your tumor’s biology might influence treatment choices, what tests are available for your type and stage of cancer and how the results could guide your treatment plan. With this knowledge, you can move ahead with greater clarity, possible fewer detours and the confidence that your care is supporting your unique situation.

Content covered in the Know More Educational Series via Susan G Komen may be an emerging area in research or technology. Talk with your doctor about what is right for you.