Low Hemoglobin (Anemia) and Cancer: What’s the Connection?

If you have cancer and feel completely exhausted, it’s totally normal — and may be treatable. One of the main side effects of cancer and its treatments is anemia — a blood disorder that can leave you feeling tired, dizzy and cold.

People with anemia have a low red blood cell count and low hemoglobin — a protein in red blood cells that helps your body exchange oxygen and carbon dioxide. When something affects your red blood cells, they can’t deliver oxygen-rich blood to tissues throughout your body. This leaves you feeling wiped out.

“Anemia can happen for several reasons, including cancer or cancer treatment,” says hematologist and oncologist Dana Angelini, MD. “Regardless of the cause, anemia can leave you exhausted and drained. In severe cases, it can be life-threatening.”

Adding anemia to your list of cancer-related concerns may feel overwhelming. But the more you know about the close link between anemia and cancer, the better you’ll be able to manage your symptoms or avoid anemia altogether.

The connection between anemia and cancer

Anemia doesn’t cause cancer. And you may have anemia for reasons that have nothing to do with cancer. For example, iron deficiency or excessive bleeding during menstruation can also cause it.

But if you have cancer and are undergoing treatment, your team will already be on the lookout for anemia because it’s very common. Up to 90% of people with cancer experience anemia as a result of:

• Chronic bleeding caused by solid tumors
• Decreased production or destruction of red blood cells when cancer affects bone marrow (the spongy center of bones where blood cells are made)
• Inflammation caused by cancer cells
• Kidney dysfunction related to cancer treatment
• Deficiency of iron, vitamin B or folate

“It’s important to identify the exact cause of anemia, beyond ‘cancer’ or ‘cancer treatment,’” Dr. Angelini clarifies. “We never leave anemia as its own diagnosis because when we understand the cause, we know how best to treat it.”

Anemia and cancer treatment

Any cancer treatment can raise your risk of anemia. Some treatments cause anemia because of how they’re given. In other cases, the side effects of treatment may also lead to anemia, especially if they affect your ability to stay hydrated and get essential nutrients.

Cancer treatments linked to anemia include:

• Chemotherapy. This treatment directly affects cancer cells. But it can also damage healthy cells, including bone marrow. Experts estimate that 70% of people receiving chemotherapy develop anemia.
• Immunotherapy. This targeted treatment can cause inflammation and, in rare cases, may harm red blood cells.
• Radiation therapy. Radiation therapy can cause bone marrow dysfunction, leading to low blood counts, especially if you have the treatment in your sternum (chest) or pelvic area.
• Targeted therapy. This can damage bone marrow and affect the production of red blood cells.

What type of cancer causes low hemoglobin?

Some types of cancer can directly lead to anemia, regardless of treatment. They include:

• Bone marrow cancers. Rooted in the bone marrow, such as multiple myeloma, lymphoma and leukemia, these are closely associated with anemia. “Anemia is often the first symptom for people diagnosed with blood cancers,” Dr. Angelini shares.
• Colorectal cancer. A common first sign of colorectal cancer is blood in your poop (stool) because the tumor may be bleeding into your digestive tract. When excessive bleeding (and blood loss) goes unnoticed, it can cause a decrease in red blood cells.
• Advanced stage, solid tumor cancers. If not treated early enough, nonblood cancers can cause high levels of cancer-related bleeding and inflammation, disturbing your production of red blood cells.

Treating anemia when you have cancer

Treating anemia is important because:

• Treatment reduces your symptoms and restores your energy.
• You’ll be better equipped to handle cancer treatment.
• If left untreated, anemia can make other chronic conditions worse.

“Sometimes, if your blood counts aren’t high enough, your team may decide to delay treatment or give a reduced dose,” Dr. Angelini notes. “Having healthy blood counts will help you get the most effective treatment for cancer.”

Your anemia treatment may include:

• Medicines that stimulate red blood cell production
• Supplements given as an IV (intravenous), shot or pill to boost iron, vitamin B12 or folic acid
• Red blood cell transfusion for severe anemia
• Reducing cancer treatment if it’s causing anemia

Tips for avoiding anemia with a cancer diagnosis

If you’ve been diagnosed with cancer, Dr. Angelini recommends the following steps to help reduce your risk of developing anemia:

• Avoid excessive alcohol, which can cause harm to bone marrow.
• Eat a well-rounded diet to ensure you’re getting vital nutrients.
• Report any unusual symptoms immediately to treat anemia and identify other health issues that may cause anemia.

“If you have cancer, it’s important to treat everything that’s happening to your body, not just the cancer itself,” emphasizes Dr. Angelini.