The Link Between Cancer and Anemia

Cancer and anemia are linked in many ways. If you have cancer, you may have anemia due to cancer itself or due to the treatments of cancer, such as chemotherapy.

People with cancer may also develop anemia due to reasons other than cancer (for reasons that people without cancer may develop anemia). If you have anemia but do not have cancer, your healthcare provider may recommend looking for cancer as a possible cause.

Let's look at the ways these two conditions are intertwined, and what you need to know to be able to identify symptoms and advocate in your own health care.

anemia symptoms
Verywell / Brianna Gilmartin

Cancer and Anemia Link

Cancer and anemia are linked in a number of ways. For those with cancer, especially colon cancer or blood-related cancer such as leukemia or lymphoma, anemia may be one of the first signs of the disease.

If you have anemia without a known cause (such as heavy menstrual bleeding), your healthcare provider may talk to you about screening for colon cancer, or other tests.

For people living with cancer, there are a number of possible causes of anemia, both those related to cancer, and those which can affect anyone with or without cancer. What do you need to know if you learn that you are anemic?

What Is Anemia?

Anemia is a deficit of red blood cells or their oxygen-transporting capacity. Anemia can result from conditions that affect red blood cells directly, or may instead be caused by iron deficiency. The hemoglobin molecules in your red blood cells contain iron, which serves to attach and transport oxygen to your tissues.

Anemia is not a diagnosis, but rather a symptom with many possible causes.

When you have anemia (whether your red blood cell count is low or the hemoglobin in your red blood cells is low) you have a reduced capacity for delivering oxygen to the tissues in your body. This can lead to symptoms such as fatigue, shortness of breath, and even unconsciousness if your anemia is severe.

Anemia Symptoms

Anemia might be accompanied by symptoms that reflect your body's deficit of red blood cells, including:

  • Feeling weak or tired all of the time
  • Shortness of breath (not related to a history of asthma or a cardiac condition)
  • Increased susceptibility to infection
  • Cold hands or feet
  • Pallor (most easy to see in the mucous membranes)
  • Pica (feeling the need to eat items that are not meant as food, such as dirt)

It's important to note, however, that not everyone who is anemic has symptoms.

If you have one or more symptoms of anemia, especially if you have a known family history of colon cancer, do not delay talking to your healthcare provider.


Some of the possible causes of anemia include:

Blood Loss

Blood loss leading to anemia can result from the loss of large amounts of blood (such as from surgery, menstruation, or a motor vehicle accident) or the chronic loss of microscopic amounts of blood (such as from polyps and tumors in the digestive tract, ulcers, or even hemorrhoids).

Blood loss may also be moderate but greater than your body's ability to keep up with the loss as is often seen among women with heavy menstrual periods.

Nutritional Deficits

A diet deficient in iron-rich foods may result in iron deficiency anemia, especially in women that have regular menstrual periods. A diet deficient in vitamin B12 can result in anemia characterized by large red blood cells (pernicious anemia). Folate deficiency can also lead to anemia.

Chronic Disease

A number of medical conditions, such as chronic kidney disease can result in anemia in which red blood cells are not small (as in iron deficiency anemia) nor large (as in pernicious anemia). This is known as anemia of chronic disease.


You may have difficulty absorbing iron from what you eat. Malabsorption can be the result of chronic intestinal diseases, such as Crohn's disease, or a result of chronic diarrhea (your body cannot absorb the iron fast enough).

Destruction of Red Blood Cells

Conditions such as autoimmune hemolytic anemia can lead to the destruction of red blood cells. This can occur in people without cancer but is particularly common in people with lymphomas. There are several drugs that can result in drug-induced hemolytic anemia including some antibiotics.

Causes of Anemia Related to Cancer

Causes of anemia which are related to cancer (either due to cancer itself or due to treatments for cancer include:

  • Bone marrow replacement: Some cancers, such as lymphomas or metastases from breast cancer can invade the bone marrow and replace the bone marrow cells which make red blood cells.
  • Chemotherapy: Chemotherapy can induce anemia.
  • Cytokines: High levels of cytokines related to some cancers can slow the production of red blood cells by the bone marrow.
  • Change in diet: Cancer itself can cause a poor appetite which can result in nutritional deficiencies leading to anemia. In addition to affecting the bone marrow, chemotherapy can cause symptoms such as mouth sores, taste changes, and loss of appetite that can lead to anemia.
  • Hemolytic anemia: As noted above

Anemia Due to Chemotherapy

Chemotherapy attacks all rapidly growing cells, not just cancer cells, and the cells in the bone marrow that are used to replace white blood cells, red blood cells, and platelets are some of the most rapidly dividing cells in the body.

Chemotherapy is a common cause of anemia in people with cancer, and this occurs with many of the drugs commonly used.

Blood counts are usually done before each chemotherapy infusion, and if the red blood cell count is too low, chemotherapy may need to be delayed. Some people with cancer are treated with medications that stimulate the production of red blood cells so that chemotherapy can continue to be given.

In a 2016 study, 90% of people receiving chemotherapy for solid tumors were noted to have anemia.

Anemia and Colon Cancer

Iron deficiency can be one of the first symptoms of colon cancer. Because the right side of your colon is distant to your rectum, blood in the stool has time to degrade and probably will not be recognizable by the time you pass it in a bowel movement.

Large tumors in this portion of the colon can continue to bleed slowly, and over time, this will be reflected in a low blood count.

In one study, 6% of people referred to a clinic due to iron deficiency anemia were found to have colon cancer. Of these people, the majority of cancers were in the right colon.

Anemia at the time of diagnosis with colon cancer was linked with a poor prognosis in the past, but this does not appear to be the case in more recent studies.


Anemia is diagnosed on a complete blood count in which a low red blood cell count or low hemoglobin levels are noted.

  • Red blood cell count: A normal red blood cell count is 4.32 to 5.72 trillion cells/L in men and 3,90 t0 5.03 trillion cells/L in women.
  • Hemoglobin: A hemoglobin level less than 13.5 grams/100 ml in men or 12.0 grams/100 ml in women is considered low.
  • Hematocrit: A normal hematocrit is 42% to 54% in men and 38% to 46% in women.

In addition to the levels, healthcare providers look at other lab tests to learn more about the potential causes of anemia. Some of these include:


As noted, when the cause of anemia is not known in someone without cancer, tests to rule out cancer, especially colon cancer and blood-related cancers may be considered, depending on factors including a person's age and more.

The treatment of anemia in people with cancer includes two primary steps. The first is the treatment of the underlying cause of the anemia, which can sometimes eliminate the cause. Treatment is also aimed at treating the anemia itself, especially if it is causing symptoms or has developed rapidly.

Treatment of the Underlying Cause

The treatment of anemia will depend on the underlying cause, which as noted, can be a number of different things. For chemotherapy-induced anemia, your next infusion may need to be canceled or delayed until your counts have increased.

If your cancer has invaded your bone marrow, treatment addressing cancer in your bone marrow will be the first step.

Treatments for Anemia

Specific treatments for anemia may include:

  • Diet: If your anemia is mild, simply eating iron-rich foods may suffice. It takes some time (on the order of months) to restore your red blood cell count through this method alone. Iron-rich foods that may make good choices include liver (chicken or beef), red meat, iron-fortified cereals, and legumes.
  • Iron supplements: Iron supplements may be prescribed, but only take these under the advice of your healthcare provider. Studies suggest intravenous iron can be very helpful for some people with anemia due to cancer. These can be constipating, so your healthcare provider may recommend a stool softener as well.
  • Blood transfusion: A blood transfusion is a way to rapidly increase your red blood cell count and is usually used if your anemia is causing significant symptoms.
  • Medications: These stimulate the production of red blood cells in your bone marrow. The drugs Procrit or Epogen (epoetin alfa) or Aranesp (darbepoetin alfa) are similar to compounds made by our own bodies to stimulate red blood cell production.
  • Steroids: Steroids are sometimes used for the treatment of hemolytic anemia with lymphomas.


Anemia can be difficult to cope with, especially the resultant fatigue. While fatigue is not dangerous on its own, many people find cancer fatigue to be one of the most annoying symptoms of cancer and cancer treatments.

Some simple measures can help as your anemia is being evaluated and treated. Standing up or sitting up slowly can help to avoid orthostatic hypotension or the decrease in blood pressure which can lead to lightheadedness or "blacking out" when going from a lying down to a standing position too rapidly.

Pacing yourself throughout the day and prioritizing activities is also helpful, as is learning to ask for help. Eating well and making sure you are hydrated is important both for anemia as well as coping with cancer itself.

Frequently Asked Questions

  • What risk factors make someone with cancer more likely to develop anemia?

    Certain chemotherapy drugs, such as platinum-based chemotherapy, can cause anemia. You are also more likely to develop anemia if you have a specific type of tumor, such as in the lungs or ovaries, or if you already had a low hemoglobin count prior to having cancer.

  • Can anemia lead to complications for people with cancer?

    Untreated and severe anemia can lead to further complications, including depression, heart problems such as arrhythmia and enlarged heart, and increased risk of infection.

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11 Sources
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