Breast Cancer Treatment and Low Red Blood Counts

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Quick summary

It's no exaggeration to say that red blood cells are the life force of the body, since they play such an essential role in carrying oxygen from the lungs to the cells. That's why when a patient's red blood count drops, she really feels it -- and shows it. She may be pale, tired, weak, and have trouble catching her breath. Here's what you need to know to understand what's happening and what to do.

Why does breast cancer cause red blood cell (RBC) counts to drop?
  • In most cases, it's not the cancer itself but breast cancer treatment that leads to a shortage of red blood cells, also called anemia. Chemotherapy often damages the bone marrow that produces red and white blood cells and platelets, a condition called bone marrow suppression, or myelosuppression. As red blood cells die out, which they do naturally every 120 days or so, the body isn't able to replace them and the red blood count drops.
  • Radiation therapy in some locations can damage red blood cell production.
  • Blood loss from surgery can also cause or exacerbate anemia.

Why is there more than one test for red blood cell counts?

There are several ways that doctors commonly measure red blood counts:

  • Red blood cell count . This test counts the number of red blood cells in a single drop (a microliter) of blood. As a general guideline, consider the normal range to be 4.2 to 5.4 million for women, 4.5 to 6.2 million for men.
  • Hemoglobin . This test measures the red-pigmented protein that carries oxygen. Normal range for red blood count is 12 to 16 grams per deciliter in women,14 to 18 grams per deciliter in men. When a patient's hemoglobin drops below 10 grams per deciliter, she's considered anemic.
  • Hematocrit . This test measures the percentage of total blood volume made up of red blood cells. Normal range is 35 to 47 percent for women, 40 to 52 percent for men.

A complete red blood count usually includes additional measures of the size, capacity, and number of red blood cells. The doctor will typically order a battery of tests to get a complete picture of the health of her patient's red blood cells. For example, a low hematocrit in combination with low hemoglobin may indicate iron deficiency, while a high hematocrit can indicate dehydration.

Can I help prevent red blood counts from dropping?

There are medications called cell growth factors (also called colony stimulating factors) that can be given along with chemo or radiation to prevent red blood counts from dropping. The growth factor that boosts production of red blood cells is epoetin or darbepoetin (brand names Procrit, Epogen, Aranesp). Growth factors can take between two and eight weeks to work, so they're not a solution for dramatic red blood cell loss. There's also a risk of side effects, so the doctor will decide whether to prescribe cell growth factors based on her assessment of the risk of developing a low red blood count.

Get as much information as you can from the doctor about your chemo regimen and the effect you can expect it to have on red blood counts . "Some drugs reduce the red blood cell count by 25 percent immediately; some drugs take a week before the count start to drop. Every drug and regimen is different," says Terry Anders, an oncology nurse at the Zangmeister Cancer Center in Columbus, Ohio. Because side effects include fluid retention and heart palpitations -- both of which can worsen heart conditions -- the doctor will take into account any possible heart problems when deciding whether to prescribe Procrit or other growth factors. Other side effects include diarrhea, vomiting, fever, and upper respiratory infection. In addition, Procrit can cause shortness of breath and edema, so if you or the person you're caring for already has these problems, the doctor may be conservative about prescribing it.

What are the symptoms of low red blood count?

The typical signs of anemia are extreme fatigue and shortness of breath, but a low red blood count can cause a host of symptoms, including pale or clammy skin, rapid heart rate, chest pain, or difficulty staying warm. Because low oxygen in the blood can affect the brain as well, some patients feel dizzy and light-headed or have difficulty concentrating or remembering things. Headaches are also common.

How low does red blood count need to go before the doctor recommends treatment?

This is a very individual decision, and the doctor will make it based more on symptoms (such as fatigue or shortness of breath) than on a particular number. It's likely the doctor will take a wait-and-watch attitude for as long as possible before recommending medication or a transfusion, because she's hoping the red blood count will rise on its own. Also, keep in mind that red blood counts aren't likely to drop dramatically right after chemo; it usually takes one to two weeks for the blood count to reach what doctors call the nadir, the point at which it drops to its lowest point. Cutoff rates vary according to different labs, but if hemoglobin drops below eight, most doctors will recommend either growth factors or a transfusion.

How long will it take my red blood count to rise again?

Red blood cells have a long life -- up to 120 days -- so rebuilding the red blood count is a long, slow process. The speed with which bone marrow makes new red blood cells is also affected by factors such as the type of treatment -- particularly the type and dosage of chemo -- and a patient's general state of health.

One thing to keep in mind is that red blood counts usually won't start dropping until a week or two after treatment and will continue to fall for several more weeks. That's because chemo doesn't kill off the red blood cells already in the bloodstream, which are mature and aren't dividing rapidly. It kills off the cells forming in the marrow, and therefore there's a delayed response that corresponds with the rate at which marrow is creating new cells. The rate of regeneration can be affected by age and overall health. Also,radiation and some medications suppress the production of red blood cells, so the rebuilding process can be much slower.

Melanie Haiken

Melanie Haiken discovered how important it is to provide accurate, targeted, usable health information to people facing difficult decisions when she was health editor of Parenting magazine. See full bio