Anemia–low red blood cell count or low hemoglobin–is common in people with cancer. Cancer-related factors linked to anemia include internal bleeding from tumors, altered production of hemoglobin, and side effects of chemotherapy.
If you have anemia without an established cause, your healthcare provider may pursue the possibility of a cancer diagnosis. Types of cancer most often associated with low hemoglobin include blood, bone, colon, and cervical cancers.
This article discusses the types of cancer linked to low hemoglobin. It also explains the ways cancer and its treatment can cause anemia and the symptoms of cancer and anemia to look for.
Cancer and Anemia Link
Anemia is the medical term for having lower-than-normal levels of hemoglobin. Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to your cells.
Anemia is often one of the first signs of cancer, especially colon or blood-related cancer, such as leukemia or lymphoma. 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.
The three leading causes of low hemoglobin levels–blood loss, decreased red blood cell production, and high rates of red blood cell destruction–are also associated with certain types of cancer and cancer treatments.
When you don’t have enough hemoglobin, you have a reduced capacity for delivering oxygen to the tissues in your body. If your anemia is severe, this can lead to symptoms such as fatigue, shortness of breath, and even unconsciousness.
Untreated and severe anemia can lead to complications, including depression, heart problems such as arrhythmia and enlarged heart, and increased risk of infection.
Cancer’s Effect on Red Blood Cells
Cancer can impact the production and storage of red blood cells in a few different ways. These include:4
- Blood loss: Tumors can bleed, causing you to lose blood. This is especially the case with colon cancer.
- 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.
- Cytokines: High levels of proteins known as cytokines, which act as molecular messengers between cells, can slow the bone marrow’s production of red blood cells.
- Hemolytic anemia can occur in people without cancer but is particularly common in people with lymphomas.
- Nutritional deficiencies: Cancer can cause a poor appetite. Chemotherapy can also cause mouth sores and taste changes that make eating challenging. This can result in nutritional deficiencies, including iron deficiency, and lead to anemia.
Types of Cancer That Cause Anemia
Anemia related to cancer can be due to blood loss from a tumor or a disruption in developing healthy red blood cells. The following cancers are associated with anemia.
Blood and Bone Marrow Cancers
Blood and bone marrow cancers alter the production and function of blood cells and can lead to anemia. This is because blood cancers cause uncontrolled growth of abnormal blood cells, interrupt healthy blood cell development. There are three main types of blood and bone marrow cancers:5
- Leukemia: Found in your blood and bone marrow, leukemia is caused by the rapid production of abnormal white blood cells, commonly used to fight infection. Abnormal white blood cells associated with leukemia hinder the bone marrow’s ability to produce red blood cells and platelets.
- Lymphoma: The lymphatic system removes excess fluid from your body and produces lymphocytes, a type of white blood cell that fights infections. Lymphoma occurs when abnormal lymphocytes collect in the lymph nodes and other tissues impairing the immune system.
- Myeloma: Plasma cells are white blood cells that produce antibodies to fight infection. Myeloma (cancer of the plasma cells) interferes with the average production of antibodies. This weakens your immune system.
Cancer in other parts of the body can also metastasize (spread) to bones and interfere with the production of red blood cells, leading to anemia.1
Research shows that about half of all people with cervical cancer have anemia at diagnosis. This is often due to bleeding tumors. It can also be due to cancer spreading to the bone marrow or malnutrition due to cancer diminishing your appetite.6
Iron deficiency can be one of the first symptoms of colon cancer. Because the right side of your colon is distant from your rectum, blood in the stool has time to degrade and probably will not be recognizable when you pass it in a bowel movement.
Large tumors in this portion of the colon can continue to bleed slowly; over time, this will be reflected in a low blood count.7
Renal cell carcinoma and other types of kidney cancer can cause anemia. The kidneys secrete a hormone called erythropoietin, which stimulates the production of red blood cells. Kidney cancer can hinder this process and cause anemia.
Cancer Treatment and Anemia
Anemia can be a side effect of cancer treatments, including chemotherapy and radiation.9
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.
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: An average red blood cell count is 4.32 to 5.72 trillion cells/L in men and 3,90 to 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: An average hematocrit level 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:
- Mean corpuscular volume (MCV): MCV gives information about the size of red blood cells, whether regular, small (such as iron deficiency), or large (such as folate and B12 deficiency).
- Red cell distribution width (RDW): RDW gives further information on the size of red blood cells and whether there are two different populations, which can point toward other causes.
- Mean corpuscular hemoglobin concentration (MCHC): MCHC gives further information about the shape of red blood cells.
- When the cause of anemia is not known in someone without cancer, tests to rule out cancer may be considered.
- Types of tests used to diagnose cancer include:
- Biopsy to test tissue samples, bone marrow, or body fluids
- Blood tests to check for tumor markers
- Endoscopic examinations, including colonoscopy, bronchoscopy, or cystoscopy
- Imaging studies such as bone scans, computed tomography (CT) scans, and magnetic resonance imaging (MRI)
- The treatment of anemia in people with cancer includes two primary steps. The first is treating 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 attributed to several different things. Your next infusion may need to be canceled or delayed for chemotherapy-induced anemia 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:11
- Diet: Eating iron-rich foods may suffice if your anemia is mild. 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 benefit some people with anemia due to cancer.12 These can be constipating, so your healthcare provider may also recommend a stool softener.
- Blood transfusion: A blood transfusion is a way to increase your red blood cell count rapidly and is usually used if your anemia is causing significant symptoms.
- Medications: These stimulate the production of red blood cells in your bone marrow. Procrit, Epogen (epoetin alfa), or Aranesp (darbepoetin alfa) are similar to compounds made by our bodies to stimulate red blood cell production.
- Steroids: Steroids are sometimes used to treat hemolytic anemia with lymphomas.