Anemia is a common blood disorder in which you do not have enough red blood cells or hemoglobin. Hemoglobin is an iron-rich protein that enables red blood cells to carry oxygen from your lungs to the rest of your body.

Symptoms related to anemia stem from this lack of oxygen-carrying capacity and can include fatigue, weakness, shortness of breath, palpitations, lightheadedness, headache, and pallor of the skin.

“Depending on how bad your anemia is, you may be asymptomatic to severe enough to require transfusions,” says Robert Diep, MD, a clinical assistant professor and medical oncologist at Stanford Medicine in California.

In some cases, anemia can be an indication of certain types of cancer. Here’s what you need to know about the connection between anemia and cancer, and what kinds of cancer can cause low hemoglobin.

Anemia is a common symptom for many people with cancer, and it’s sometimes the first sign of cancer or progressive disease in a patient’s cancer journey, says Dr. Diep.

There are several reasons why cancer and anemia are linked.

Cancer Cells Crowd Out Healthy Blood Cells Some cancers that affect the bone marrow, such as leukemia or lymphoma, can invade and disrupt the production of red blood cells. The bone marrow is responsible for making blood cells, including red blood cells. When cancer cells take over this space, it leads to reduced production of healthy red blood cells, which lowers hemoglobin levels.

Chemotherapy and Radiation Anemia can be related to the treatments a patient might receive to treat their cancer, says Diep.

It is not unusual to see multiple factors contributing to a patient’s anemia in the context of cancer, says Diep.

While any type of cancer can potentially lead to anemia, certain cancers are more likely to affect red blood cell production or cause bleeding, thereby leading to low hemoglobin levels.

Your bone marrow is the factory that makes all your blood cells. It is therefore no surprise that anemia is common in many types of hematologic cancers that can involve the bone marrow, such as myelodysplastic syndrome, multiple myeloma, leukemia and lymphoma. Other cancer types have high rates of anemia too, especially ones that have the potential of bleeding, which includes some genitourinary, gynecologic, or gastrointestinal malignancies.

Blood Cancers: Leukemia, Lymphoma, and Myeloma

Your bone marrow is the factory that makes all your blood cells, Diep explains. That’s why blood cancers that directly impact blood cell production in the bone marrow are likely to cause anemia.

• Leukemia Leukemia is a cancer of the bone marrow and blood that causes abnormal white blood cells to multiply uncontrollably. These abnormal cells take up space in the bone marrow, crowding out healthy red blood cells. As a result, patients with leukemia often experience low hemoglobin levels. Additionally, leukemia cells use a lot of iron to support their rapid growth, which can lead to iron deficiency.

• Lymphoma Lymphoma, which includes both Hodgkin lymphoma and non-Hodgkin lymphoma, is a cancer that starts in the lymphatic system. Anemia is common in this type of cancer because lymphoma cells can infiltrate the bone marrow and interfere with red blood cell production.

• Multiple Myeloma Multiple myeloma is a cancer that affects plasma cells in the bone marrow. These cancerous cells can crowd out healthy blood cells and cause a reduction in red blood cell production, leading to anemia. At least 60 to 70 percent of people with multiple myeloma have anemia when they are diagnosed.

Solid Tumor Cancers

While blood cancers have a more direct impact on blood cell production, solid tumor cancers can also lead to anemia, often through mechanisms like bleeding, bone marrow infiltration, or chronic inflammation.

• Bone Cancer Bone cancer, such as osteosarcoma, can infiltrate the bone marrow, where red blood cells are produced, leading to anemia. Additionally, treatments for bone cancer, such as surgery or chemotherapy, can also suppress red blood cell production.
• Cervical Cancer Cervical cancer can lead to anemia due to chronic blood loss. As the tumor grows, it may cause irregular bleeding, which depletes the body’s iron stores and reduces red blood cell levels.
• Colon Cancer Colon cancer often causes anemia because it can lead to bleeding in the gastrointestinal tract. Even small amounts of blood loss over time can result in iron-deficiency anemia. The cancer may also disrupt the bone marrow’s ability to produce healthy blood cells.
• Prostate Cancer Prostate cancer may cause anemia in two main ways: through bone marrow infiltration and the use of androgen deprivation therapy (ADT). Androgens are hormones that support red blood cell production, and ADT treatments suppress these hormones, leading to lower red blood cell counts.

Other Cancers Linked to Anemia

Other cancers, such as lung cancer and breast cancer, are also associated with anemia.

• Lung Cancer Lung cancer is linked to iron deficiency due to a combination of factors such as chronic inflammation, poor appetite, and bone marrow infiltration.

• Breast Cancer In breast cancer, low hemoglobin levels can occur before chemotherapy begins, but they tend to get worse after treatment as chemotherapy suppresses red blood cell production.

Anemia can cause a range of symptoms, which can vary in severity depending on how low your hemoglobin levels are. Common symptoms of anemia include:

• Fatigue and weakness
• Pale skin or an ashen complexion
• Shortness of breath, especially during physical activity
• Dizziness or lightheadedness
• Rapid or irregular heartbeat
• Cold hands and feet
• Chest pain (in severe cases)

It’s important to recognize that there are many different types of cancer, and there are many different causes of anemia, says Diep.

“Anemia may be unrelated to cancer but can sometimes be related directly or indirectly to cancer and subsequent treatments. People should ask their doctor for a full workup to address all treatable causes of anemia,” he says.

A systematic approach is used in diagnosing anemia, which involves various lab tests to find the likely cause, says Diep.

Lab tests can show hemoglobin level, serum iron level, reticulocyte (immature red blood cells) count, serum ferritin level (which shows how much iron your body stores), and your iron-binding capacity, which shows if you have too little or too much iron in your blood.

Other tests may include:

• Tests on body fluids such as stool, urine, sputum, or vomit to check for blood
• A bone marrow biopsy to make sure the bone marrow is making healthy red blood cells
• An MRI or a CAT scan to look for bleeding in the body

“In a patient with a preexisting cancer diagnosis, the workup for anemia is generally the same, although we often see anemia related to inflammation and treatment-related anemia more often,” he says.

Providers will also review historical lab trends in case the anemia may have been present long before, and is therefore possibly unrelated to, the cancer diagnosis, says Diep.

Treating anemia is an essential part of managing cancer, as low hemoglobin levels can impact a person’s ability to tolerate cancer treatments. The goal of treatment is to restore normal red blood cell counts and ensure the body can get the oxygen it needs.

The treatment of anemia follows what the likely cause is, says Diep.

“For example, in iron deficiency anemia, you would focus on replenishing the patient’s iron stores, which is important for hemoglobin synthesis,” he says.

Blood transfusion: If the anemia is especially severe, patients may undergo transfusion, says Diep.

Cancer treatments may also need to be adjusted if a person has anemia. If chemotherapy is causing the anemia, doctors may recommend lowering the dose or switching to a different treatment regimen.

• Anemia is common in cancer patients and can be caused by cancer itself, treatments, chronic bleeding, or inflammation, leading to low hemoglobin and reduced oxygen supply.
• Blood cancers like leukemia, lymphoma, and myeloma are more likely to cause anemia by disrupting bone marrow and interfering with red blood cell production.
• Solid tumor cancers, including colon, prostate, and cervical cancers, can cause anemia through bleeding, bone marrow infiltration, or treatment side effects like chemotherapy.
• Symptoms of anemia include fatigue, weakness, shortness of breath, and pale skin; early detection and treatment are crucial to prevent complications and allow for the best possible outcomes.