Erythroleukemia is a cancer of the blood and bone marrow. It’s a rare subtype of acute myeloid leukemia (AML) and is sometimes called acute erythroid leukemia or M6-AML.

Erythroleukemia occurs in 3% to 5% of all people with AML. Erythroleukemia is different from other subtypes of AML because it mostly involves a type of blood-forming cell called the erythroblasts.

Knowing your subtype of AML can be very important in determining the best treatment options available. If a doctor has diagnosed you with erythroleukemia or you’re not sure which subtype of AML you have, talk with your doctor to learn how your AML subtype might affect your treatment and outlook.

Erythroleukemia occurs when your body produces a large amount of abnormal red blood cells in the blood and bone marrow.

The bone marrow is a soft tissue found in the center of your bones. It’s responsible for producing new blood cells and other important cells in your body.

There are two types of bone marrow:

  • Red bone marrow makes red blood cells, white blood cells, or platelets.
  • Yellow bone marrow makes cartilage, fat, or bone cells.

AML occurs when there’s a problem with the cells in the red bone marrow known as myeloid cells.

In AML, damage occurs to the DNA of developing blood cells. Scientists don’t know the exact cause of this DNA damage. The DNA damage makes your blood cells start to grow and divide uncontrollably.

These quickly dividing cells don’t work properly and don’t die off at a natural point in their life cycle, unlike healthy blood cells. Instead, they build up and spread around the body. Over time, the cancer cells outnumber healthy cells in the blood.

As a subtype of AML, erythroleukemia still happens in the red bone marrow. But it mainly affects specific red bone marrow cells called erythroblasts. Erythroblasts are cells that make erythroid cells, a type of red blood cell.

Erythroleukemia can occur at any age and in both male and female individuals but usually affects men with an average age of 65 years. It’s occasionally also present in very young children.

Doctors consider it very rare. The only large study to track the total number of cases across a population group took place in England in the 1980s and 1990s. It found that this type of cancer occurs in less than 1 in a million people per year.

Erythroleukemia can also occur with other cancers, including myeloproliferative neoplasms or myelodysplastic syndromes (MDS).

Other risk factors include:

  • history of exposure to ionizing radiation
  • history of chemotherapy treatment for another cancer
  • rare genetic chromosomal abnormalities

Over time, the abnormal blood cells can outnumber healthy blood cells. Not having enough healthy blood cells in your body can cause the following symptoms:

Your doctor will ask about your symptoms, take a medical and family history, and conduct a physical exam.

Doctors can’t diagnose erythroleukemia from just a single test. To diagnose erythroleukemia and differentiate it from other subtypes of AML or other blood cancers, doctors will take a blood or bone marrow sample to send to a lab for testing.

Blood and bone marrow tests for erythroleukemia may include the following:

  • Complete blood count (CBC): A CBC uses a sample of your blood to count the number of red blood cells, white blood cells, and platelets. People with AML often have a high number of white blood cells and a low number of red blood cells and platelets.
  • Peripheral blood smear: A blood smear looks at the shape, size, and amount of cells in the blood. This test looks specifically for leukemia (blast) cells, which aren’t normally in the blood.
  • Cytochemistry: This test exposes blood cells to chemical stains (dyes) that react with specific types of leukemia cells. This test, in particular, can help your doctor differentiate between AML and acute lymphocytic leukemia.
  • Bone marrow aspiration and biopsy: A doctor may take a bone marrow sample or a small section of bone containing marrow and examine it under a microscope.
  • Flow cytometry: This test helps identify specific markers on cells by seeing if certain antibodies stick to them. Flow cytometry can help classify AML into different subtypes. This is called immunophenotyping.
  • Molecular tests: These tests look for specific changes in the chromosomes (long strands of DNA) and genes in leukemia cells.

Doctors will then use this information to understand what subtype of AML you have based on a classification system developed by the World Health Organization (WHO).

Doctors previously divided erythroleukemia into two categories (erythroleukemia of erythroid/myeloid type and pure erythroid leukemia), but this is no longer the case. Scientists have proposed that erythroleukemia should fall into a category of blood cancers known as MDS. However, there’s still some debate on how doctors should classify these cancers.

Treatments for erythroleukemia are similar to treatments for the other subtypes of AML.

The current treatment includes intensive chemotherapy and stem cell transplants.

Chemotherapy drugs work by destroying cancer cells and keeping them from multiplying. Chemotherapy can also affect healthy cells and cause many side effects.

Common side effects from chemotherapy include:

Stem cells are special human cells that can develop into many different cell types, including red blood cells. Stem cell transplants, also called bone marrow transplants, restore bone marrow cells lost due to chemotherapy.

Not everyone with erythroleukemia qualifies for a stem cell transplant. A stem cell transplant is a very intensive process and comes with many risks, including:

  • infection
  • bleeding
  • lung problems
  • graft-versus-host disease, which is a condition in which the donor’s cells attack your body
  • hepatic veno-occlusive disease
  • graft failure, which means that the transplanted cells don’t produce new cells as expected

Doctors often measure outlook in terms of 5-year overall survival. The 5-year overall survival describes the percentage of people with a certain disease who are still alive 5 years after their diagnosis.

The 5-year survival rate for AML is 30.5%, according to the National Cancer Institute.

Keep in mind that the 5-year survival rate is calculated based on past data. It doesn’t take into account recent advances in treatments or new research that leads to a better understanding of a disease.

In general, the outlook is worse for people with erythroleukemia compared with other types of AML because erythroleukemia can be harder to treat than other types of AML. Since it’s so rare, there’s no 5-year survival rate available. According to a few older studies, the median survival for erythroleukemia is between 3 and 9 months.

Many other factors can affect your outlook apart from the subtype. According to the American Cancer Society, these factors also play a role in your outlook and response to treatment:

  • chromosomal abnormalities
  • genetic mutations
  • markers on the leukemia cells
  • white blood cell counts
  • having another blood disorder
  • infections
  • where in the body the cancer has spread
  • your age and general health

Erythroleukemia is a rare blood cancer and a subtype of AML. Though the outlook is considered worse than other types of AML, much progress has been made in recent years to help understand the features and gene changes that cause this type of blood cancer. This information could be useful to scientists as they try to develop new therapies.

If you have erythroleukemia, your doctor may recommend enrolling in a clinical trial to study new treatment options. Be sure to talk with a doctor about the potential benefits and risks of joining a clinical trial.