When you have cancer, you will typically find out what “stage” the disease is in. This stage is usually based tumor growth and development for most types of cancer.
Leukemia is a blood cancer and doesn’t cause tumors to form. Instead, leukemia staging is based on the amount of cancerous white blood cells that are circulating in the body.
There are four main types of leukemia. Each type affects your body in different ways and has its own staging system.
In this article, we dive into these four main types of leukemia, break down the stages, and what discuss what they mean.
Leukemia is a blood cell cancer. It can happen when the body makes too many white blood cells. These white blood cells divide rapidly and don’t allow other cells to grow.
There are four main types of leukemia:
- Acute lymphocytic leukemia (ALL). ALL is a quickly progressing form of leukemia that causes healthy immune cells to turn into cancerous white blood cells. Most cases of ALL are diagnosed in children.
- Acute myelogenous leukemia (AML). AML begins in your bone marrow and is the most common form of leukemia. It occurs in both children and adults. Without treatment, AML can rapidly progress in the body as new white blood cells continue being made.
- Chronic lymphocytic leukemia (CLL). CLL is primarily diagnosed in people over age 55. Like ALL, it causes changes to your immune cells, but it progresses much less rapidly.
- Chronic myelogenous leukemia (CML). CML also starts in your bone marrow, but it progresses less rapidly than AML. This form of leukemia is primarily seen in adults.
ALL is generally staged based on your WBC count at the time of diagnosis. ALL is found in immature WBCs and spreads rapidly.
ALL is found in both adults and children. Doctors don’t assign traditional numbers when staging ALL in either group.
Childhood ALL stages
Children with ALL are staged by risk group. There are two risk groups for childhood ALL:
- Low risk. Children under age 10 with a WBC count of less than 50,000 are considered low risk. Children generally have a higher ALL survival rate than adults. Additionally, having lower WBC count at the time of diagnosis is associated with higher survival rates.
- High risk. Children with a WBC count of over 50,000 or who are older than age 10 are considered high risk.
Adult ALL stages
ALL staging for adults is broken into three stages:
- in remission
Anyone with a new diagnosis of ALL will be in this stage. “Untreated” simply means that your diagnosis is recent. This is the stage before you begin receiving treatment to destroy the cancer cells.
Remission occurs after cancer treatments. You’re considered to be in the remission stage when:
- Five percent or less of the bone marrow cells in your body are cancerous.
- Your WBC is within normal limits.
- You no longer have any symptoms.
You’ll likely have more lab tests at this stage to look for any remaining cancer in your body.
There are two subtypes of ALL remission:
- complete molecular remission: when there is no evidence of cancer in your bone marrow
- minimal residual disease (MDR): if evidence of cancer can still be found in your bone marrow
People with MDR are more likely to have their cancer come back. If you’re in MDR, your doctor might need to be monitored more closely for signs you’re no longer in remission.
This stage occurs when your leukemia comes back after remission. You’ll need another round of testing and more treatment in this stage.
AML grows rapidly and is found throughout your bloodstream. It can affect both children and adults, although children have a higher survival rate than adults.
Doctors generally don’t stage AML. Instead, AML is divided into subtypes. The subtypes are determined by looking at the maturity of the leukemia cells and where they came from in your body.
There are two methods of dividing AML into subtypes. The French-American-British (FAB) system was developed in the 1970s and divides AML into nine subtypes:
- M0: undifferentiated acute myeloblastic leukemia
- M1: acute myeloblastic leukemia with minimal maturation
- M2: acute myeloblastic leukemia with maturation
- M3: acute promyelocytic leukemia
- M4: acute myelomonocytic leukemia
- M4 eos: acute myelomonocytic leukemia with eosinophilia
- M5: acute monocytic leukemia
- M6: acute erythroid leukemia
- M7: acute megakaryoblastic leukemia
These subtypes are based on where the leukemia began. Subtypes M0 through M5 begin in the WBCs. Subtype M6 starts in RBCs, and stage M7 starts in the platelets.
FAB subtypes aren’t staging, so higher numbers don’t mean your prognosis is worse. However, the FAB subtype does affect your survival odds:
- High survival rate. You’ll generally have a better prognosis if your AML subtype is M1, M2, M3, or M4eos. Subtype M3 has the highest survival rate of all FAB AML subtypes.
- Average survival rate. Subtypes M3, M4, and M5 have average AML survival rates.
- Low survival rate. People with subtypes M0, M6, and M7 have a worse prognosis because these subtypes have a lower survival rate than the average for all AML subtypes.
FAB subtypes are still widely used to classify AML. However, in recent years, the World Health Organization (WHO) has broken down AML into further subtypes. WHO subtypes look at the cause of the AML and how it affects your prognosis.
WHO subtypes include:
- AML with certain genetic abnormalities
- AML related to previous chemotherapy or radiation treatments
- AML related to the disruption of blood cell production (myelodysplasia)
- AML that doesn’t fit into one of the three groups above
There are multiple further subtypes of AML within each WHO subtype. For example, each chromosomal abnormality that can cause AML has its own subtype with certain genetic abnormalities. Your WHO subtype can be used along with your FAB subtype to help your doctor develop a treatment plan that may work best for your situation.
CLL is a slower-growing form of leukemia that is found in mature WBCs. Because it grows slowly, it is staged similarly to other forms of cancer than to either ALL or CML.
Rai staging system for CLL
Doctors stage CLL using the Rai staging system. The Rai system is based on three factors:
- the number of cancerous WBCs in your body
- the number of RBCs and platelets in your body
- whether or not your lymph nodes, spleen, or liver are enlarged
There are five RAI stages for CLL, which progress in severity. In higher CLL stages, the body is no longer making the needed amount of RBCs and platelets. Higher stages represent a worse prognosis and a lower survival rate.
- CLL stage 0. In this stage, there are too many abnormal WBCs, called lymphocytes, in your body (generally more than 10,000 in a sample). Your other blood counts are normal in this stage, and you won’t have any symptoms. Stage 0 is considered low risk.
- CLL stage I. In stage I, there is a lymphocyte count of more than 10,000 per sample, just like stage 0. In stage 1, your lymph nodes will also be swollen. Your other blood counts are still normal in this stage. Stage 1 is considered intermediate risk.
- CLL stage II. In stage II, your liver or spleen has become enlarged in addition to the swollen lymph nodes. The level of lymphocytes is still high, but your other blood counts are normal. Stage II is considered intermediate risk.
- CLL stage III. In stage III, your other blood cells start to be affected. People in stage III are anemic and don’t have enough RBCs. The lymphocyte count is still too high, and swelling of the lymph nodes, spleen, and liver are common. Stage III is considered high risk.
- CLL stage IV. In stage IV, in addition to all of the symptoms from the previous stages, your platelets and RBCs are affected, and your blood won’t be able to clot normally. Stage IV is considered high risk.
Binet staging system for CLL
Sometimes doctors will use a different system to stage CLL. The Binet staging system uses the number of tissue groups affected by lymphocytes and the presence of anemia to stage CLL. There are three stages in the Binet system:
- Binet stage A. In stage A, less than three areas of tissue are affected. There is no anemia or trouble with normal clotting
- Binet stage B. In stage B, there are three or more areas of affected tissue. There is no anemia or trouble with normal clotting
- Binet stage C. In stage C, there is anemia, trouble with clotting, or both. The presence of anemia or trouble with clotting is always stage C, no matter how many tissue areas are affected.
When you have CML, your bone marrow produces too many WBCs called blast cells. This cancer progresses slowly. The blast cells will eventually grow to outnumber the healthy blood cells.
Staging is based on the percentage of cancerous WBCs in your body. Doctors divide CML into the following three stages.
Chronic phase CML
Less than 10 percent of the cells in your bone marrow and blood are blast cells in the chronic phase. Most people in this stage have fatigue and other mild symptoms.
CML is often diagnosed in this phase and treatment begins. People in the chronic phase normally respond well to treatment.
Accelerated phase CML
In the accelerated phase, between 10 and 19 percent of the cells in the bone marrow and blood are blast cells. The accelerated phase occurs when the cancer doesn’t respond to treatment in the chronic phase.
You may have more symptoms during the accelerated phase. Accelerated phase CML doesn’t respond as well to treatment.
Blastic phase CML
Blastic phase is an aggressive stage of CML. More than 20 percent of your blood and bone marrow cells will be blast cells. The blast cells will have spread throughout your body, making treatment more difficult. You might also have a fever, fatigue, poor appetite, weight loss, and swelling of your spleen.
A medical professional will order a few different kinds of tests if they think you might have any form of leukemia. The types of tests you need will depend on your specific situation but often include:
- Complete blood count. With a complete blood count, you’ll have blood drawn to measure the amount of red blood cells (RBCs), white blood cells (WBCs), and platelets in your blood. This can help doctors determine if you have too many white blood cells and if they are abnormal.
- Tissue biopsy. A biopsy of your bone marrow or lymph nodes might be ordered to look for leukemia. This test will also help doctors determine what type of leukemia you have and if it has spread.
- Organ biopsy. You might need a biopsy of an organ, such as your liver, if your doctor suspects the cancer has spread.
Once your doctor has these results, they’ll be able to diagnose you with leukemia or rule it out. If you have leukemia, they’ll be able to tell you what type you have and what stage it is in.
Cancer staging helps doctors figure out the best treatment plan for your specific case. Leukemia is staged differently than other cancers because it shows up in the blood instead of with tumors.
Higher survival rates are associated with lower or earlier stages, while more advanced stages generally mean a lower survival rate. Even though the staging looks different than with other forms of cancer, leukemia staging is a very helpful tool to determine the best treatment for you.