Triple-Positive Breast Cancer

Triple-positive breast cancers grow in response to sex hormones and a protein called HER2. As part of your diagnosis, a provider will test the cancer cells. The cancer is triple-positive if results show that cancer cells are:

• Estrogen-receptor positive (ER+): Cancer cells grow in response to estrogen.
• Progesterone-receptor positive (PR+): Cancer cells grow in response to progesterone.
• HER2-positive (HER2+): Cancer cells have too much HER2 protein, which fuels their growth.

About 10 in every 100 females diagnosed with breast cancer have this type. In the past, it was one of the worst types to get. This is because HER2+ breast cancers are often aggressive (fast-growing).

But today’s treatments fight HER2+ breast cancers effectively. People with triple-positive breast cancer are living longer lives, free of cancer.

Symptoms of triple-positive breast cancer

Triple-positive breast cancer symptoms are the same as breast cancer symptoms, in general. The most common sign is a new lump in your breast or armpit.

Breast lumps can be cancerous or benign. Only a healthcare provider can tell the difference. This is why you should get checked if you find a new lump.

Triple-positive breast cancer causes

This cancer happens when a breast cell transforms (mutates) into a cancer cell. Experts don’t know what causes the mutation.

They do know that, just like normal breast cells, the cancer cells have hormone receptors and HER2 proteins. In healthy cells, these things help control cell growth and development.

But these same features allow cancer cells to make more cells. The cells may form a tumor. Without treatment, the cancer can spread.

Risk factors

The risk factors for triple-positive breast cancer are the same as for breast cancer. For example, breast cancer risk increases with age. Having a mutation in your BRCA1 or BRCA2 genes also increases your risk. You inherit these mutations from a biological parent.

But most people with breast cancer don’t have these genes. Triple-positive breast cancer isn’t hereditary. Most involve gene changes that happen during your lifetime.

How doctors diagnose this condition

Healthcare providers use lab tests to diagnose triple-positive breast cancer. First, they’ll do a biopsy. This involves removing tissue from the lump and sending it to a lab to test for cancer. They may also test your lymph nodes.

If they find cancer, they’ll check for excess HER2 proteins on the cells. They’ll look for estrogen and progesterone receptors. If the cells have all three, you have triple-positive breast cancer.

Other tests used

You’ll also need imaging procedures that show where the cancer is located in your body. Imaging helps your provider stage cancer. Staging shows how much it’s spread. Like receptor status, cancer stage helps your provider plan treatment.

How is triple-positive breast cancer treated?

The most common treatment is surgery to remove the tumor. You may need chemotherapy or radiation therapy after surgery to destroy cells that surgery may have missed. You may need these treatments before surgery to shrink the tumor so it’s easier to remove.

Other treatments prevent cancer from using HER2 and hormones to grow.

Targeted therapy

Targeted therapy treatments prevent HER2 from fueling cancer cell growth. Types include:

• Antibody-drug conjugates
• Monoclonal antibodies (the most well-known is trastuzumab)
• Tyrosine kinase inhibitors

Most people receive targeted therapy alongside chemotherapy treatment. You usually get these treatments as an IV (through a vein). You may need to continue targeted therapy after you finish chemotherapy. Targeted therapy usually takes about a year.

Hormone therapy

Hormone therapy blocks hormones that fuel cancer cell growth. It usually involves taking a pill. Examples include:

• Aromatase inhibitors
• Gonadotropin-releasing hormone agonists
• Tamoxifen

Most people are on hormone therapy for at least five years. But how long you’ll need it depends on cancer stage and treatment side effects.

When should I see my healthcare provider?

Let your provider know if you’re having symptoms that may mean cancer has come back. Tell them about new or unexpected treatment side effects.

Ask which symptoms or side effects mean you should go to the emergency room.

What is the prognosis for triple-positive breast cancer?

HER2-positive breast cancer had one of the worst prognoses before targeted therapies. Now, treatments that can block the effects of HER2 have completely changed the outlook.

According to the National Cancer Institute (U.S.), more than 90 out of 100 women are alive five years after their diagnoses. Typically, the earlier your cancer stage, the better your outcomes.

What is the recurrence rate of triple-positive breast cancer?

Medical experts are still learning how long treatment sends triple-positive breast cancer into remission (no signs or symptoms of cancer). But targeted therapy and chemotherapy together may reduce the risk of cancer coming back.

ER+ breast cancers grow slowly but can return years after treatment. Your provider may suggest that you continue hormone therapy to reduce the risk.