Many people with cancer develop anemia, an abnormally low number of red blood cells. Because red blood cells carry oxygen throughout your body, anemia interferes with your organs and tissues getting the oxygen levels they need, which can cause fatigue and other symptoms. The condition can be mild or severe and life-threatening. It can be caused by the cancer itself, your cancer treatment, or related factors, like nutrition. Anemia can also have other causes separate from cancer. Having this condition can sometimes cause a delay in treatment or impact its effectiveness. During your cancer treatment, it’s important to monitor for signs of anemia and talk to your healthcare team if you notice any symptoms.
Here’s what you need to know about anemia and cancer.
Some people with mild anemia have no symptoms or don’t notice them, but the signs can get worse over time if the anemia worsens. The most common symptoms of anemia are:
- Muscle weakness
- Dizziness, lightheadedness or fainting
- Rapid heart rate, pounding heart, or irregular heartbeat (arrhythmia)
- Pale or yellowish skin (this can be especially visible in your gums, lips and tongue and beneath your fingernails)
- Shortness of breath/labored breathing, especially with exertion (climbing stairs, etc.)
- Difficulty concentrating
- Chest pain that comes and goes
- Feeling cold, especially in the hands and feet
Causes of anemia
There are three main ways your body can end up with a low count of red blood cells:
- Your body’s ability to make new red blood cells is impaired.
- Something in your body is destroying red blood cells after they are produced.
- You are losing blood faster than your body can replace it.
Sometimes it’s a combination of these factors that cause anemia. People with cancer can become anemic as a result of any or all of these factors. Both cancer and its treatments can disrupt red blood cell production. Some blood cancers and certain kinds of tumors can cause red blood cell destruction. Bleeding from a tumor can also cause anemia.
Cancer and red blood cell counts
To understand why anemia is common in cancer patients, it helps to know how red blood cells work in your body. Your body’s cells, tissues and organs need oxygen to function. Red blood cells carry oxygen from your lungs to the rest of your body (they also bring the waste product carbon dioxide back to your lungs to be removed from your body when you exhale).
Hemoglobin is the part of your red blood cells that carry oxygen and carbon dioxide. Hemoglobin’s high iron levels are what make your blood red. (This is why the low red blood cell and hemoglobin levels of anemia can make your skin look pale).
Your bone marrow produces new blood cells following a hormonal signal secreted by your kidneys. Some of the building blocks of your red blood cells include nutrients
you get from your diet, especially iron, folate and vitamin B-12.
This process of generating new red blood cells can be disrupted if something interferes with your nutrient levels or the regular functioning of your kidneys or bone marrow. Cancer and cancer treatments can interfere with this process in several ways, and they can also impact how long red blood cells survive in your body.
Chemotherapy, radiation and other cancer treatments target cells that divide quickly, since this is a feature of cancer cells. However, certain healthy cells also divide rapidly, including some cells in the bone marrow involved in blood cell production. So these cells can be harmed by cancer treatments and cause anemia.
Below are the most common factors that lead to anemia in people with cancer. Often, several factors combine to cause anemia:
Cancer causes inflammation. Inflammation changes the way your body uses iron, making it less available for use in new red blood cell production.
Cancer that affects bone marrow
Cancer can damage blood marrow directly. This is the case with blood cancers like leukemia, lymphoma, and multiple myeloma, and with other kinds of cancer that spread to the bone or bone marrow. The cancer can take over space usually used for new red blood cell production.
Cancer that affects the kidneys
Kidney cancer can interfere with the hormonal signaling needed to prompt red blood cell production.
drugs can damage bone marrow, slowing down the creation of new blood cells (the term for this is myelosuppressive). This can cause anemia for several months after chemotherapy, but blood counts usually improve with time.
Some chemotherapy drugs can impact kidney function, especially platinum-based drugs like carboplatin (brand name Paraplatin), cisplatin (brand name Platinol) and oxaliplatin (brand name Eloxatin).
Radiation therapy can damage bone marrow. This is more likely to cause anemia if you get radiation to a large area of your body or to bones with large amounts of bone marrow, like the pelvic bones.
Bleeding can cause low red blood cell counts by causing you to lose blood cells faster than your body can make new ones. In addition, certain types of cancer are more likely to cause bleeding that leads to anemia, including cancers in the GI tract, like colon and stomach cancer, and cervical cancer. Rapid tumor growth can sometimes cause bleeding. Surgery can also cause bleeding that leads to temporary anemia.
Even without significant blood loss, major cancer surgery can sometimes cause temporary anemia by affecting bone marrow and impairing red blood cell production. It’s not fully understood why this happens, but some researchers think it could be related to the impacts of surgery on immune system function.
Cancer and cancer treatment can cause low appetite and vomiting, which can reduce your levels of nutrients needed to make new red blood cells.
Red blood cell destruction
Certain kinds of cancer can cause the destruction of red blood cells in the body (hemolysis).
Other causes of anemia
Causes of anemia unrelated to cancer include inherited blood disorders like sickle cell disease and thalassemia, heavy menstruation, pregnancy, bleeding from stomach ulcers, poor nutrition, certain infections and medication side effects, autoimmune disorders and a number of other chronic health issues, like kidney or heart disease.
Anemia can be temporary (as with menstruation or pregnancy) or chronic. Red blood cell counts can fluctuate depending on what’s causing the anemia. If you have a history of anemia or kidney or liver problems before cancer, you may have a higher risk of anemia during cancer treatment. Be sure to let your healthcare team know your full medical history.
There are three main treatments used to help people with cancer who develop anemia.
These drugs work by mimicking the hormonal signal from your kidneys that normally prompts your bone marrow to make more red blood cells. The naturally occurring hormone is erythropoietin, so these medications are referred to as erythropoiesis-stimulating agents (ESAs). Examples are epoetin alfa (brand names Procrit, Epogen and Retacrit) and darbepoetin alfa (brand name Aranesp). They are given by injection every week or every few weeks.
Iron supplements can help ensure you have one of the essential nutrients needed to build hemoglobin. Iron pills or getting more iron through your diet is usually not enough for people with cancer-related anemia. Iron injections are more effective and tend to have fewer side effects. Usually these will be combined with ESA medications.
If your anemia is severe, you might need a blood transfusion to quickly boost your hemoglobin and red blood cell levels. Your doctor can tell you at what point you should expect to need a blood transfusion (usually they look at your hemoglobin levels on your blood labs).
If low nutrient levels besides iron are contributing to your anemia, you may need to get extra folic acid or vitamin B-12 through either pills or injections. Be sure to discuss any supplements you plan to take on your own with your doctor, as they may have specific recommendations for you, based on the treatment you are getting and the type of cancer you have.
The bottom line on anemia and cancer
Cancer-related anemia often goes away with time after treatment. Its symptoms can impact how you feel, especially your energy level, and can lead to delays in treatment and other health impacts, so it’s important to watch for signs of anemia and tell your healthcare team if you notice them or if they get worse. To manage the fatigue and weakness anemia can cause, try to conserve energy for the most important activities. Get plenty of rest. Keeping a log of your symptoms can help your healthcare team understand and treat your anemia. Try to eat a healthy, balanced diet and talk to your healthcare team if you have a low appetite, nausea or vomiting so you can ensure you get all the nutrition you need.