The PIK3CA mutation, and why it may matter for your cancer care

Knowing what type of metastatic breast cancer (MBC) you have and what causes your cancer to grow is important. If you’re living with MBC, you may already know your MBC type, often defined by your tumor's hormone receptor (HR+/-, also known as ER+/- or PR+/-) and HER2 protein (HER2+/-) status. But it’s also important to know your MBC mutation status, such as PIK3CA.

Like your HR and HER2 status, your tumor’s PIK3CA mutation status may affect your cancer care.

MBC Types

Click on your type below to learn about the hormones, proteins and mutations that make it grow.

Types of Metastatic Breast Cancer
+

The PIK3CA gene is the most commonly mutated gene in HR+/HER2- breast cancer, affecting about 40% of people with this type. It's important to know if you have a PIK3CA mutation, as it can affect how your cancer progresses.

Types
+

HR+/HER2- breast cancer is the most common form of breast cancer. In this cancer, hormones estrogen and progesterone cause the cancer to grow. There are also certain mutations that could impact your cancer and treatment options, such as if you have the PIK3CA mutation.

+

HR+/HER2+ is fueled by estrogen or progesterone hormones, as well as the HER2 protein.

+

HR-/HER2- breast cancer, commonly referred to as Triple Negative Breast Cancer (TNBC) is not fueled by estrogen, progesterone or the HER2 protein. Research shows that this type is most common in younger women, African American women and women who have the BRCA1 mutation.

+

HR-/HER2+ breast cancer has a mutation in the HER gene causing excess HER protein, which makes the cancer grow. HR-/HER2+ MBC commonly has the characteristics of inflammatory breast cancer (IBC). IBC typically develops from cells that line the milk ducts of the breast and then spread beyond the ducts. IBC is often initially diagnosed as advanced. IBC is not always HR-/HER2+, so talking to your doctor about your type of breast cancer is still recommended.

Understanding PIK3CA, and what it means for you

What is a PIK3CA mutation in metastatic breast cancer?

What it is

A PIK3CA mutation is not inherited (cannot be passed down to children). The PIK3CA gene is the most commonly mutated gene in HR+/HER2- breast cancer, affecting about 40% of people with that subtype. PIK3CA mutations have been linked to cancer growth.

Why knowing your PIK3CA status matters

Why it matters

Just as your tumor's HR and HER2 status inform your doctor whether certain proteins fuel your cancer, your tumor’s PIK3CA mutation status tells your doctor whether a gene mutation may be contributing to the growth of your cancer.

Your tumor’s PIK3CA mutation status may affect how your doctor manages your cancer care.
Identifying a PIK3CA gene mutation

What you can do

Talk to your doctor about how you can find out your tumor’s mutation status.

Identifying the PIK3CA mutation can help your doctor understand your disease better and plan your personalized care.
Questions to ask your doctor include
Questions to ask your doctor include:
  • How do I know if my tumor has a PIK3CA mutation?
  • How does having a PIK3CA mutation impact my cancer care?

Let’s talk more about mutations in MBC.

What is a mutation?

Mutations are like typos in your DNA

In cancer, mutations may affect how the tumor grows.

What are the types of mutations?

Sporadic mutations

Sporadic Mutations:

occurs at random and is not passed down from parent to child. PIK3CA is a sporadic mutation.

Genetic mutations

Inherited Mutations:

passed down from parent to child. BRCA1/2 is an inherited mutation.

MBC Mutation Myth vs. Fact
  • MYTH

    I already know my MBC type – I do not need to know anything else about my cancer.

    fact

    There may be a mutation called PIK3CA in your tumor that could impact your cancer care. Talk to your doctor to learn more about your tumor's PIK3CA mutation status.

  • MYTH

    All MBC mutations are passed down from parent to child.

    fact

    The PIK3CA mutation is not inherited, which means you may have it regardless of your family history.

  • MYTH

    Mutations in cancer do not affect course of disease (or disease prognosis).

    fact

    PIK3CA mutations have been linked to cancer growth, and are associated with poorer prognosis.

  • 1 of 3

Watch the video below to learn more about the PIK3CA mutation.

If you'd like to print this resource to bring to your next appointment with your healthcare provider, click the button below.

DOWNLOAD PDFArrow