People with cancer may develop anemia due to cancer treatment, blood loss, or decreased red blood cell production. Without treatment, anemia can cause complications.

Anemia happens when a person has a reduced number of red blood cells or a decrease in hemoglobin in their blood. Hemoglobin is essential for carrying oxygen from the lungs to the tissues throughout the body. Many factors, including underlying medical conditions such as cancer, can lead to anemia.

This article looks at anemia as a complication of cancer, how doctors diagnose anemia, and the treatment for it.

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People with anemia may experience a variety of symptoms, including:

Learn more about anemia.

People with cancer may experience anemia for several reasons, including those listed below.

Chronic blood loss

This can occur in gastrointestinal cancers, such as colon, stomach, and rectal cancer, and gynecological cancers, such as uterine and cervical cancer. Blood loss can result in iron deficiency anemia, as iron is a key component of hemoglobin, which carries oxygen in red blood cells.

Bone marrow suppression

Cancer can affect the bone marrow, which produces red blood cells. Certain cancers, particularly leukemia and lymphoma, can enter the bone marrow and crowd out normal blood-forming cells.

Chemotherapy effects

Many chemotherapy drugs can suppress bone marrow function, decreasing red blood cell production. This is a common cause of anemia in people who are undergoing chemotherapy.

Inflammatory cytokines

Some cancers produce inflammatory cytokines that can interfere with red blood cell production. These cytokines can suppress the bone marrow’s ability to make red blood cells, leading to anemia.


In some cases, cancer can lead to the destruction of red blood cells (hemolysis). This can occur in certain types of cancer, such as multiple myeloma, and result in anemia.

Kidney problems

Some cancers and cancer medications can affect the kidneys’ ability to produce erythropoietin, a hormone that stimulates red blood cell production. When there is not enough erythropoietin in the body, anemia can develop.

B12 deficiency

Some chemotherapy drugs — specifically pemetrexed (Alimta) — can decrease vitamin B12 levels and cause B12 deficiency anemia. The body uses B12 to make red and white blood cells and platelets. Doctors address a deficiency with B12 supplementation. Some gastrointestinal cancers can also cause B12 deficiency.

Without treatment, anemia can cause several complications, including:

  • Impaired cognitive function: Anemia can affect cognitive function, leading to difficulties with concentration, memory, and decision making.
  • Decreased tolerance to cancer treatments: Anemia may reduce a person’s tolerance to cancer therapies such as chemotherapy and radiation therapy. This can lead to treatment delays, dose reductions, or discontinuation of treatment, which may mean that the cancer therapy is less effective.
  • Impaired wound healing: Anemia can hinder the body’s healing ability after surgical procedures, making postsurgery recovery more challenging.
  • Dizziness and falls: People with anemia have a higher risk of experiencing dizziness and lightheadedness, which can lead to falls and injuries, especially in older adults.

Doctors typically use a blood test to diagnose anemia.

A complete blood count measures various components of the blood, including:

  • red blood cell count
  • hemoglobin level
  • hematocrit, which is the proportion of blood composed of red blood cells
  • mean corpuscular volume, which measures the size of red blood cells

Learn more about tests to diagnose iron deficiency anemia.

Typically, treatment for anemia involves addressing the underlying cause.

Other possible treatments include:

Read more about medications to treat anemia.

The approach to managing anemia may differ based on the specific type and its severity.

People should rest when possible and prioritize the most important tasks each day.

It is important to choose nutritious foods and make dietary changes if necessary, including:

Learn how to get more iron from the diet.

Below are answers to some frequently asked questions about anemia and cancer.

What type of cancer causes anemia?

Various types of cancer can cause anemia, primarily due to the way cancer affects the body.

Colorectal cancer, stomach cancer, esophageal cancer, leukemia, lymphoma, and multiple myeloma more commonly have an association with anemia.

Is anemia always associated with cancer?

People can develop anemia for many reasons, not only due to cancer. Iron deficiency is the main cause of anemia, but chronic kidney disease, autoimmune disorders, rheumatoid arthritis, inflammatory conditions, chronic infections, and certain medications are other possible causes.

Not everyone who has cancer will develop anemia.

The outlook for someone with cancer-related anemia varies widely. It depends on several factors, including the underlying cause of anemia, the type and stage of cancer, the person’s overall health, and the effectiveness of treatment.

Cancer-related anemia is manageable, and many people see improvements with appropriate treatment and cancer management. However, in some cases, particularly when the cancer is advanced or there are limited treatment options, anemia may be more challenging to treat.

Some people with cancer develop anemia. This condition can have various causes, such as decreased red blood cell production, blood loss, and some types of cancer treatment.

Treatment for anemia usually involves addressing the underlying cause, but doctors may also recommend iron supplements or infusions. Lifestyle strategies, such as eating iron-rich foods, can help as well.