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.
If anemia lasts long enough and isn’t treated, it can cause serious complications, including organ damage.
“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.
Low red blood cell counts can also be caused by cancer treatments or something other than cancer.
In people with cancer, anemia is linked with a higher likelihood of poor outcomes, including death, and reduced quality of life.
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.
Chronic Bleeding Certain cancers, such as colorectal cancer or stomach cancer, may cause internal bleeding, which can result in a gradual loss of red blood cells. Over time, this leads to a condition called iron-deficiency anemia, as the body runs low on the iron needed to produce new red blood cells.
Chemotherapy and Radiation Anemia can be related to the treatments a patient might receive to treat their cancer, says Diep.
Cancer treatments like chemotherapy and radiation can suppress bone marrow activity, making it harder for the body to produce red blood cells.
Chronic Inflammation Some cancers produce systemic inflammation, which can interfere with the body’s ability to produce red blood cells. This is particularly true for cancers that have spread (metastasized), as they produce signals that disrupt normal blood cell production.
It is not unusual to see multiple factors contributing to a patient’s anemia in the context of cancer, says Diep.
Anemia in cancer patients is typically classified as iron-deficiency anemia or anemia of chronic disease. Iron-deficiency anemia occurs when the body doesn’t have enough iron to make red blood cells, while anemia of chronic disease is a type of anemia caused by underlying conditions like cancer, where inflammation or bone marrow disruption prevents red blood cell production.
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)
People experiencing any of these symptoms should discuss them with their healthcare provider. They may be caused by low hemoglobin or anemia caused by a number of different factors, including cancer.
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.
Anemia is diagnosed through a complete blood count (CBC) test, which measures various components of your blood, including red blood cells and hemoglobin levels. Anything lower than these values may indicate anemia.
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.
Iron supplements: The first line of treatment for iron-deficiency anemia is usually iron supplements. These can come in the form of oral pills or intravenous (IV) iron, depending on the severity of the deficiency. Foods rich in iron, such as red meat, beans, and leafy greens, can also support your body’s ability to produce healthy red blood cells.
Blood transfusion: If the anemia is especially severe, patients may undergo transfusion, says Diep.
Medications: In some cases, medications like erythropoiesis-stimulating agents (ESAs) may be used to encourage the production of red blood cells. ESAs have been linked to certain adverse events, and so the risk-benefit ratio needs to be assessed by your provider.
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.
