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The Link Between Anemia and Cancer

Anemia can be a symptom of many types of cancer, including cancers of the blood, as well as those affecting the digestive system, such as colon and stomach cancers. What’s more, certain cancer treatments may cause anemia.   

What Causes Anemia? 

Anemia occurs when the body’s level of red blood cells is too low. Red blood cells carry a protein called hemoglobin, which delivers oxygen from the lungs to every cell in the body. The cells need oxygen to produce energy and survive. When there aren’t enough red blood cells to provide adequate oxygen to cells, anemia is the result.  

There are many causes of anemia. In some cases, this condition may occur because the body doesn’t make enough red blood cells. In other cases, disease or illness may destroy blood cells. Excessive bleeding, such as from trauma, can also cause the body to lose red blood cells and develop anemia.  

Several forms of cancer can cause anemia. Red blood cells are made in the bone marrow, which is the spongy tissue at the center of many bones. Several forms of cancer damage bone marrow, including leukemia, lymphoma, and multiple myeloma, which can interfere with the healthy production of red blood cells and cause anemia. What’s more, colon cancer, stomach cancer, and other cancers of the digestive system can promote bleeding in the intestinal tract that may result in a loss of red blood cells and anemia symptoms. In general, cancer can promote inflammation, which may also harm red blood cells.  

However, anemia can also occur due to cancer treatment. For example, both radiation and chemotherapy can damage bone marrow, resulting in loss of production of red blood cells and anemia. Also, some forms of chemotherapy can harm the kidneys, which produce a protein called erythropoietin that signals the bone marrow to make red blood cells. Chemo-related kidney damage may, then, result in anemia. Also, a healthy, balanced diet is needed to provide the nutrients necessary to make red blood cells. Loss of appetite due to chemotherapy treatment may deprive the body of those building blocks, causing a drop in red blood cells.  

Other Causes of Anemia 

Anemia is a common problem, so in some patients it may not be related to cancer or cancer treatment. Three significant causes of anemia include iron deficiency, B12 deficiency, and folic acid deficiency. 

Iron is one of the essential components of hemoglobin; in iron deficiency, hemoglobin cannot be produced, and anemia occurs. This condition, known as iron-deficiency anemia, can result from eating a diet that’s low in this essential mineral, as well as some gastrointestinal problems. In addition, iron deficiency occurs in some women due to excessive blood loss during menstruation. 

Folic acid and vitamin B12 also have important roles in the production of red blood cells. Therefore, a diet that’s low in folic acid and B12 can also lead to anemia. In particular, consuming little or no red meat may lead to vitamin B12 and iron deficiency, while people who eat few or no vegetables may also suffer from a folic acid deficiency. Eating a balanced diet can prevent anemia. (Vegetarians and vegans should be sure to consume sources of iron and B12, such as legumes, leafy greens, dairy products, and fortified foods.) 

Blood loss due to trauma or internal bleeding can also cause anemia. Inherited forms of anemia occur due to genetic factors. Thalassemia (Mediterranean anemia) and sickle cell anemia are two examples of inherited anemia. 

Anemia Symptoms to Look Out For

Anemia can have many symptoms, but the most obvious are: 

  • Extreme fatigue 
  • Weakness 
  • Pale skin, especially in the face, eyes, or nail beds 
  • Dizziness 
  • Palpitations 
  • Forgetfulness 
  • Hair loss 
  • Tinnitus (ringing in the ears) 
  • Chills 
  • Shortness of breath 
  • Cracked lips 


If a doctor suspects that you may have anemia, he or she will first take a medical history. In particular, the doctor will ask about your diet and whether you have family members who have experienced anemia. The doctor will also perform a physical examination, looking out for any key symptoms or signs of anemia. 

A key test in the diagnosis of anemia is called a complete blood count, or CBC. Your doctor will ask you to visit a lab for a blood draw. The lab will then analyze the blood sample. A CBC test evaluates many aspects of the blood. If a doctor suspects anemia, he or she will be particularly interested in the level of red blood cells, how much space they take up in your blood (called hematocrit) and their size (mean corpuscular volume), and the level of hemoglobin.  

People with certain types of cancer will be monitored routinely for anemia with CBC tests.  

In some cases, a doctor may recommend additional testing when diagnosing anemia, such as a bone marrow test. In these tests, needles are used to extract a small amount of fluid from the bone marrow. There are two types of bone marrow tests, which are often performed together, known as aspiration and a biopsy. Fluid taken from bone marrow will be studied in a lab, which may help to identify the cause of anemia.  


The treatment a doctor recommends for anemia will depend to some extent on what’s causing the problem and the severity of the patient’s symptoms. For cancer patients experiencing anemia, two possible treatments include: 

  • Blood transfusions: In a blood transfusion, the patient receives healthy red blood cells from a donor. 
  • Erythropoiesis-stimulating agents (ESAs): ESAs are drugs that mimic the activity of erythropoietin, meaning that the stimulate the production of red blood cells in bone marrow. These drugs may be used to treat anemia in patients who are receiving chemotherapy for cancer. 

If anemia is caused by lack of nutrients, then a doctor may also recommend dietary changes to include more foods rich in iron and folic acid, as well as vitamin and mineral supplements.  


Anemia usually responds well to treatment. Once a doctor has determined the type and cause of anemia a patient is experiencing, an appropriate treatment method can be selected. Over time, the patient’s energy level will rise, other symptoms will diminish, and quality of life can improve. 

Sources:, National Heart, Lung, and Blood Institute 

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