September 11, 2022

Link Between Metastatic Breast Cancer and Anemia

Treatments like chemotherapy and radiation can cause your red blood cell levels to decrease

Nurse drawing blood from female patient.

As the most advanced stage of breast cancer, metastatic breast cancer develops when cancer cells have spread to other parts of your body like your lungs, bones, brain or liver.


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There’s a whole host of symptoms you may experience as you go through your metastatic breast cancer treatment, from fatigue to constipation. But did you know that certain chemotherapy, radiation, targeted therapies and immunotherapies can also cause anemia?

You can develop anemia if you don’t have enough red blood cells, which help supply oxygen to the organs in your body. You may feel cold, tired or short of breath if you’re anemic.

So, why should you be concerned about anemia if you have metastatic breast cancer?

Certified family nurse practitioner Annie Dickerson, MSN, FNP-C, ACHPN, explains the connection between anemia and metastatic breast cancer and how anemia is treated.

What causes anemia in people with metastatic breast cancer?

Having anemia while going through metastatic breast cancer treatments is very common. And there are a few different reasons you may develop anemia.

First, it can be due to your chemotherapy, targeted therapy or immunotherapies. And even some forms of radiation can cause anemia. These treatments can cause damage to your healthy red blood cells as they work to kill dividing cells in your body — regardless of if they’re cancer cells or normal cells.

“Your treatment could be affecting your blood counts,” explains Dickerson. “Radiation can cause anemia depending on where the radiation is given. For example, if a patient receives radiation to their sternum or pelvis, their blood cells could be affected because these are main areas that blood cells are made.”

Another reason anemia can occur if you have metastatic breast cancer is that the cancer cells are affecting your bone marrow.

“Your body isn’t able to produce the red blood cells like a healthy person would be able to, and that can affect your red blood cells, thus causing anemia,” says Dickerson.


Managing anemia while battling metastatic breast cancer

The symptoms you may experience with anemia can vary from person to person. Some cases can be mild, while others may be severe. In some cases, you can be anemic and not experience any side effects.

Symptoms can include:

  • Dizziness or weakness.
  • Fast heartbeat.
  • Fatigue.
  • Feeling cold.
  • Headache.
  • Pale skin, dry skin or skin that easily bruises.
  • Restless legs syndrome.
  • Shortness of breath.
  • Sore tongue.

“You might be short of breath even if you’re just sitting because you don’t have as many red blood cells in your body to carry the oxygen,” notes Dickerson. “Those red blood cells are needed for you to feel good, and that’s why your skin might be pale, because your red blood cells help make your skin pink and make us look healthy.”

To help manage the side effects of anemia especially fatigue, Dickerson recommends making sleep a priority.

“And take breaks when you need to and pace yourself when you are doing activities,” she advises. “Those are key, regardless of if you have anemia or not, in the metastatic setting.”

She also suggests staying as active as possible to also help with fatigue.

Exercise or even just moving actually helps fatigue to some degree,” she says. “I’m not saying to go run a marathon, but go for a walk and try to do chores around the house, if you can.”

How is anemia treated?

Your cancer care team will ask for bloodwork routinely, whether that’s once a week or once a month, to monitor your blood counts and make sure you aren’t anemic. The typical test used is a complete blood count, also known as the CBC. This can show how many red blood cells you have, as well as what shape they are and how big they are.

If your blood counts are low, your care team may recommend a blood transfusion. While there are other treatment options available for anemia, Dickerson says that when you’re dealing with metastatic breast cancer and anemia together, a blood transfusion is really your best option.


“Why we opt for blood transfusions over other kinds of management is that most of the time when we see anemia in metastatic breast cancer individuals, it’s because of the treatment we’re giving,” states Dickerson. “We know that’s why they have anemia. Trying to treat it other ways isn’t effective.”

A blood transfusion is used to replace your blood or some of its components like red blood cells that are too low. It’s a common procedure that’s given through an intravenous line (IV) and uses donated blood or components of blood.

How much blood or blood components you need will factor into how long each blood transfusion will take. But on average, it can take anywhere from one to three hours.

And how often you may need a blood transfusion depends on your blood counts. While some individuals may only need one or two transfusions, your doctor may recommend you receive one weekly.

How to prevent anemia during breast cancer treatment

While increasing iron intake through your diet or taking iron supplements may help most people who have anemia, it hasn’t been proven to work for those with metastatic breast cancer.

That’s because the cancer treatments — chemotherapy, radiation, targeted therapy or immunotherapy — are the cause of your anemia.

It’s key that you talk to your doctor and your care team about any symptoms you may be experiencing, like fatigue and dizziness, because while it could be due to anemia, there are plenty of other possible symptoms you may experience just because you have cancer.

“There’s a lot of reasons that you could have other symptoms,” says Dickerson. “Having an ongoing conversation with your medical team is important.”

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