What Type Of Cancer Causes Low Hemoglobin?

If you or a loved one has cancer, then you’ll already know that many unpleasant side effects can occur from both the cancer itself and the treatment. One of those is anemia. So, what type of cancer causes low hemoglobin, affects your red blood cell count, and reduces your blood's ability to transport oxygen?

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What is hemoglobin?

Hemoglobin is a protein that exists inside your red blood cells. In fact, it's responsible for the red color of your blood. Hemoglobin is the protein that transports oxygen from your lungs to the rest of your body and then carries carbon dioxide to your lungs to be released.

There are several different types of hemoglobin, but all of them have one thing in common, and that is the vital role played by iron. Iron in hemoglobin binds oxygen in a reversible manner, meaning it can easily be extracted again. Note that rust is also caused by iron binding with oxygen, which is why rust and blood are similar in color.

What is anemia?

Anemia is a condition in which your body is not producing either enough hemoglobin or enough red blood cells to allow for adequate oxygenation of the body’s tissues. It can also be caused by significant blood loss, such as after surgery, an injury, or childbirth. In this case, your body is "behind" on replacing the lost hemoglobin.

Insufficient hemoglobin means insufficient oxygen being transported through your body to your organs, including your brain. It can cause pale skin, headaches, lethargy, slow thinking, and potential complications to your heart and brain.

Is there a link between cancer and anemia?

Yes, at two levels. The short answer to "what type of cancer causes low hemoglobin?" is "All of them, potentially." Additionally, in some cases, cancer may be found because you have anemia.

Somewhere between 30 and 90% of patients with cancer also have anemia. A different study gives the numbers as 40–64%. Anemia may be caused by the cancer itself or by the treatment protocols being used to bring it under control.¹ ²

Most doctors assume that cancer patients are likely to become anemic at some point during treatment if they are not already.

While all cancers can cause anemia, some are more likely to do so. These include:

  • Gastrointestinal cancer, such as gastrointestinal tract adenocarcinoma. This impacts iron absorption and can result in gastrointestinal bleeding, which can cause anemia. This is the most common form of cancer found as a result of a diagnosis of anemia.³

  • Hairy cell leukemia. In this cancer, the bone marrow makes too many lymphocytes. These cells then crowd out the red blood cells.⁴

  • Myelodysplastic syndrome (MDS). This is a type of cancer in which immature blood cells do not mature or are not healthy. There are several types of this syndrome. This is also something often found because you have anemia.⁵

  • Other forms of leukemia

  • Most forms of lymphoma

  • Multiple myeloma

  • Cancer that spreads to the bone or bone marrow. This results in your body producing fewer red blood cells or too many white blood cells, which can crowd out red blood cells and cause anemia.

Cancer can also cause:

  • PRCA (pure red cell aplasia). This syndrome is characterized by severe anemia and the absence of erythroblasts from bone marrow, meaning that your bone marrow is producing few or no red blood cells. It is strongly associated with lymphoproliferative disorders such as non-Hodgkin lymphoma and acute lymphoblastic leukemia.

  • Myelophthisic anemia. In this type of anemia, normal marrow elements are replaced by a neoplastic process, resulting in fewer red blood cells. This is common with metastatic cancers and hematological malignancies.

  • Autoimmune hemolytic anemia. In this, your immune system attacks your red blood cells, which occurs in lymphoid malignancies and ovarian cancer.

  • Cancer-related MAHA (microangiopathic hemolytic anemia). This occurs when cancer recurs. It is a paraneoplastic syndrome that results in elevated plasma hemoglobin (meaning hemoglobin is not being properly contained in red blood cells) and lactate dehydrogenase and often leads to renal failure.

The other way cancer causes anemia is as a side effect of treatment. The worst culprit is chemotherapy, which damages your bone marrow. This damage is temporary, and once you stop chemo, your blood should recover.

However, you may need an iron infusion or a blood transfusion to help your body become healthy. Patients with gynecological cancers or lung cancer are at higher risk of chemotherapy-induced anemia. 

Platinum-based therapies also increase your risk. Radiation therapy can also cause anemia if it covers a large area of the body or is targeted at bones.

Extensive research is being done to move away from systemic chemotherapy and radiation therapy because of the significant side effects they cause, including anemia.

Additionally, other side effects of these treatments can cause or worsen anemia, such as vomiting and loss of appetite. This results in you not getting enough nutrients, including iron. The cancer itself can also result in loss of appetite and, thus, insufficient iron intake.

If a tumor causes bleeding inside your body, this can cause anemia by making you lose red blood cells faster than your body can make them.

Because anemia is so common in patients, your doctor will monitor your blood for signs of anemia while you are being treated. If you are at particular risk, treatment may start proactively.

How is anemia diagnosed in cancer patients?

Anemia is diagnosed in cancer patients the same way it is typically found in the general population, through a complete blood count (CBC). This is often done as part of routine screening (and, as mentioned, is an early detection method for some cancers).

Diagnosis involves taking a blood sample, counting the red and white blood cells, and looking at the health of red blood cells under a microscope. Anemia may cause a difference in the size or color of the red cells, which can be detected visually.

If you are at risk of anemia because of your cancer or your treatment, your doctor will do a CBC on you regularly to watch for signs of anemia. They may also recommend you do some things proactively, including increasing your iron intake.

Your doctor may also look for other causes of your anemia. For example, anemia can be caused by a bleeding stomach ulcer, which may not be directly connected to your cancer (except in the way that cancer increases stress). This then requires proper treatment. While it is most likely that your anemia is caused by your cancer, it is important to remember that there may be another independent cause too.

How is cancer-induced anemia treated?

In these cases, anemia is a symptom of either the cancer itself or of the treatment designed to get rid of the cancer. It is likely that anemia related to cancer will decrease as newer targeted therapies, with fewer systemic side effects, become more common.

If you are diagnosed with anemia, you may receive one of a number of treatments:

  • A red blood cell transfusion to replace your lost or damaged blood cells. This is usually warranted if you are having significant symptoms of anemia. If you are at high risk of chemotherapy-induced anemia, a transfusion might be considered before you start treatment.

  • Erythropoiesis-stimulating agents (ESAs). These are a class of medications that tell your bone marrow to increase its production of red blood cells. These drugs are typically given to compensate for the bone marrow-damaging impact of chemotherapy. However, they are not used if you are receiving chemotherapy to send your cancer into remission or if you are not on chemotherapy. They also interact with some treatments for multiple myeloma. They are typically given if your chemotherapy is palliative or if you have a low-risk myelodysplastic syndrome. This is because ESAs have serious health risks, including an increased risk of blood clots.

  • Supplements of iron, folic acid, or vitamin B12. You might also get a vitamin B12 injection to help you absorb it better.

  • Dietary advice to increase your iron intake by consuming foods such as red meat, beans, nuts, dried fruit, or enriched bread or cereal. This can be challenging if your cancer treatments are impacting your appetite. It's a good idea to get a referral to a registered dietitian who can give you personalized advice. If you are relying on plant-based sources of iron due to personal choice or because meat has become unappetizing, you may need to consume more iron as these sources are harder to absorb.

Managing anemia is part of your overall cancer treatment. As it may not be possible to completely mitigate your anemia, you will also need to manage symptoms. The most important thing to do is rest when you need to and eat as healthily as possible.

The lowdown

Many cancers cause anemia. Some do so directly by impacting red blood cell production or health. Others may cause it less directly, such as by causing you to reduce your food intake because of appetite loss or nausea.

Cancer treatments can also cause anemia. Most cancer patients have anemia at some point and should take steps to avoid it, such as increasing their consumption of iron-containing foods or taking supplements. Talk to your doctor before taking supplements, however. Some forms of cancer may be first detected because you are anemic.

You are at high risk of anemia regardless of your type of cancer but are at even higher risk if your cancer affects your blood,  bones, or bone marrow. All types of cancer thus increase risk, but cancers such as non-Hodgkin's lymphoma or hairy cell leukemia increase it further. You should talk to your doctor about your risk of anemia and whether you should take steps to lower that risk.

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