How Fast Can HER2-Positive Breast Cancer Spread?

If you have HER2-positive (HER2+) breast cancer, you’re likely to have a lot of questions for your doctor.

For example, you may wonder: How fast does HER2-positive breast cancer spread or metastasize? Where does HER2-positive breast cancer spread to? What symptoms should I watch out for?

While it can be overwhelming to learn you have a type of invasive breast cancer, oncologist Shimoli Barot, MD, answers these questions and explains where it may spread and what symptoms to watch out for.

Why does HER2-positive breast cancer spread quickly?

“HER2 is a protein on the cell that drives the growth of the cancer,” says Dr. Barot. “This specific subtype is seen in about 20% of individuals who get diagnosed with breast cancer. It means the HER2 protein is expressed more than normal on their cells and that is what drives the cancer to grow very fast and aggressively.”

HER2-positive breast cancer can spread faster than other breast cancers — about 1 in 4 individuals with early stages of this disease will see their HER2-positive breast cancer metastasize. It can help to put it into context with other types of breast cancers.

“HER2-positive breast cancers are aggressive but aren’t the most aggressive,” clarifies Dr. Barot. “Triple-negative breast cancer (TNBC) is the most aggressive breast cancer.”

Where does HER2-positive breast cancer spread?

When HER2-positive breast cancer metastasizes, that means it has spread to one or more of the following areas of your body:

• Liver.
• Lungs.
• Bones.
• Brain.
• Skin.
• Distant lymph nodes.

Many factors can determine your HER2-positive breast cancer survival rate, such as where the cancer has spread to and how much has spread. Your age and other medical conditions also contribute to how aggressively your doctor can treat your HER2-positive breast cancer.

One of the best things you can do is avoid relying on what you may find during a late-night stress-induced internet search.

“When you search for HER2-positive metastatic breast cancer life expectancy, it can show some frightening numbers. But that doesn’t accurately reflect the data from newer treatments we have today,” notes Dr. Barot. “Today, with the advanced treatments and clinical trials, we’re seeing patients who are living longer and with better quality of life.”

Symptoms to watch for

HER2-positive breast cancer has many of the same symptoms as other kinds of breast cancer, like:

• A change in the size, shape or contour of your breast.
• A mass or lump.
• A marble-like hardened area under your skin.
• A change in the look or feel of your skin on your breast or nipple.
• Discharge from your nipple that’s clear or blood-stained.

Dr. Barot says many people will ask her if a bilateral or double mastectomy prevents their cancer from coming back or spreading.

“For people at a very high risk, such as those with hereditary gene changes, this surgery can significantly reduce the chances of recurrent cancer in the breast. But when breast cancer metastasizes, it spreads through your lymphatics and your blood to different organ systems in the body, and this surgery doesn’t reduce the risk of breast cancer spreading in other parts of the body,” she explains.

Dr. Barot says there are some additional symptoms to watch out for depending on where your breast cancer has spread.

Liver

If your cancer has metastasized to your liver, you may feel abdominal pain in your upper right side. This can also result in fluid buildup in your belly, which may lead to a distended or swollen stomach.

“It can also cause blockages of the liver ducts, so sometimes, jaundice may occur,” says Dr. Barot.

Lungs

If your breast cancer has spread to your lungs, you may feel shortness of breath. Fluid can also build up around your lungs and contribute to a cough and shortness of breath that progressively gets worse.

Bones

If cancer is found in your bones, you may feel pain in certain areas.

“It’s not like an arthritic or muscular kind of a pain, but is usually a much deeper aching pain that stays constantly and just doesn’t get better,” says Dr. Barot. “And when cancer spreads to the bones, your bones can become weak, which can lead to fractures.”

Brain

If your cancer spreads to your brain, you may start to notice symptoms like:

• Headaches.
• Seizures.
• Trouble speaking, seeing or hearing.
• Memory issues.
• Mood or personality changes.
• Weakness.
• Dizziness.
• Loss of balance
• Numbness.
• Nausea and vomiting.
• Confusion.

“When breast cancer spreads to the brain, there can be swelling in the brain, which can intensify these symptoms,” says Dr. Barot. “Many individuals may need to take steroids to calm the inflammation and swelling. There can be an increased risk of seizures in some individuals, so we may suggest antiseizure medications as well.”

Skin

Cancer can spread to your skin and show up as lumps and bumps, says Dr. Barot.

“We can see them anywhere including the scalp, chest, back or abdominal area,” she notes. “Keep an eye out for new lumps and bumps or ones that are getting bigger or growing over time.”

Distant lymph nodes

It can be tricky to know if your cancer has metastasized in your lymph nodes.

“Your distant lymph nodes, especially the ones in your chest and abdomen, aren’t something you can usually feel until they’re big enough to cause compression and you may feel the symptoms from the organs they’re compressing on,” says Dr. Barot.

Bottom line?

If you notice new symptoms or symptoms that don’t get better or improve within two to four weeks, Dr. Barot says it’s time to talk to your doctor.

“Bring it to the attention of your healthcare team so they can help you decide if something is worrisome and address your concerns: Should we do scans for this? Or is this something we can still watch and monitor?” she advises.

And if you find out that your cancer has spread to other areas of your body, there are many avenues your doctor can take. Depending on what stage your cancer is, there are many treatment options available like radiation, chemotherapy, surgery and targeted therapy.

“For early-stage cancer (Stages I, II and III), we’re usually treating with curative intent, which means we’re aiming to cure you,” says Dr. Barot. “Once it spreads and becomes Stage IV [4], we can’t cure it in most cases, but we can still treat it. This means that most people are on some form of cancer-directed treatment for the rest of their life.”