What Type of Cancer Causes Low Hemoglobin (Anemia)?

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 cancers, bone cancer, colon cancer, and cervical cancer.

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 cancer 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 main 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. This can lead to symptoms such as fatigue, shortness of breath, and even unconsciousness if your anemia is severe.

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:

• 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 production of red blood cells by the bone marrow.
• Hemolytic anemia: This 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 it hard to eat. 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 the development of 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, which interrupt the development of healthy blood cells. There are three main types of blood and bone marrow cancers:

• Leukemia: Found in your blood and bone marrow, leukemia is caused by the rapid production of abnormal white blood cells, which are normally 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 normal 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.

Cervical Cancer

Research shows about half of all people with cervical cancer have anemia at the time of 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.

Colon Cancer

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 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.

Kidney Cancer

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.

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.

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 Symptoms to Look Out For

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

• Cold hands or feet
• Dizziness
• Fatigue
• Feeling weak or tired all of the time
• Headache
• Increased susceptibility to infection
  
• 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)
• Rapid heartbeat
• Shortness of breath (not related to a history of asthma or a cardiac condition)

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

Diagnosis

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 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: A normal 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 normal, small (such as in iron deficiency), or large (such as in 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 different causes.
• Mean corpuscular hemoglobin concentration (MCHC): MCHC gives further information about the shape of red blood cells.

Diagnosing Cancer

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 tests, including colonoscopy, bronchoscopy, or cystoscopy
• Imaging studies such as bone scans, computed tomography (CT) scans, and magnetic resonance imaging (MRI)

Treatment

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 attributed to 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, 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.

Coping

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 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.