HER2-positive metastatic breast cancer is a type of cancer that starts in the breast and then spreads, or metastasizes, into other areas of the body, such as the lungs, liver, bones, or brain. HER2-positive means the cancer cells have more than a normal amount of HER2 proteins on the outside of the cells. These proteins signal the cells to continue to grow.This article will review the possible symptoms of HER2-positive metastatic breast cancer. 

Frequent Symptoms 

Symptoms of HER2-positive breast cancer are generally the same as metastatic breast cancer that is not HER2-positive. What symptoms are experienced will depend upon the organ or part of the body where the cancer is growing. The most common sites for breast cancer to spread are the brain, bones, lungs, and liver.

Brain

If there is cancer in the brain, symptoms can include:

  • HeadachesDizzinessVision changesFeeling off balanceSeizuresNausea and vomitingConfusion

Bones

When cancer is growing in the bones, symptoms can include pain in the bone or joint, or maybe swelling in the area around the bone. Sometimes, the cancer weakens the affected bone, increasing the risk of a break, or fracture. 

Lungs

If cancer cells move into the lungs, it can cause these symptoms:

  • CoughShortness of breathPain

Liver

If cancer cells spread to the liver, some symptoms that may be seen are:

  • Itching of the skinYellowing of the skin or whites of the eyesDark, tea-colored urineEnlargement or swelling of the abdomenNausea

Rare Symptoms 

It is rare for HER2-positive breast cancer to spread to areas of the body outside of the brain, bones, lungs, and liver. If breast cancer does spread elsewhere, it may cause the following symptoms:

Eyes

If breast cancer cells invade the eye tissue, there can be visual changes and swelling to the eye.

Reproductive organs

If breast cancer spreads into the female reproductive organs such as the ovaries, uterus, or vagina, there may be pelvic pain or vaginal bleeding.  

Complications

HER2-positive breast cancer that spreads into other areas of the body outside of the breast can be a life-threatening problem. 

The cancer cells that invade healthy tissues can cause those other organs to fail. 

When to See a Doctor/Go to the Hospital 

If any symptom that comes up feels like a medical emergency or seems life-threatening, it is important to seek medical help immediately. 

Symptoms that develop gradually and are persistent, without any improvement, should be discussed with your healthcare provider, so that a quick evaluation of the cause of the symptom can be discovered. 

Summary 

Metastatic HER2-positive breast cancer can cause a variety of symptoms. These symptoms vary depending on the part of the body being affected. Breast cancer most commonly spreads to the brain, bones, lungs, or liver. 

A Word From Verywell

If you have a diagnosis of HER2-positive breast cancer and you start to notice new symptoms, notify your healthcare team quickly. These symptoms should be evaluated to see if metastatic cancer is the reason you’re having them. However, it is also important to remember that not every symptom will be due to cancer.