Staging is a process that helps doctors understand how far a type of cancer has progressed and how likely it is to spread. Based on this information, they’re able to develop a treatment plan that suits the patient’s personal needs.
For most cancers, the stage depends on the size, location, and extent of the tumor. Leukemia, however, is different because it is a blood cancer. Because leukemia produces cancerous cells in the blood and bone marrow, it doesn’t typically produce a tumor that can be measured and biopsied. This means that leukemia staging is rather different from other types of cancer-producing solid tumors.
When the oncologic hematologist assesses a leukemia patient’s stage, there are several factors considered, including:
In chronic lymphocytic leukemia (CLL), the leukemia cells may spread from the blood and bone marrow to other parts of the body, such as the lymph nodes, liver, and spleen. It is important to know whether these cells have spread in order to provide the patient with the best leukemia treatment options.
The most commonly used staging and classification systems used by doctors to describe CLL are the Rai system and the Binet System.
The Rai system is based on lymphocytosis, an increase in the number or proportion of lymphocytes (a type of white blood cell) in the blood that isn’t linked to any other cause, such as an infection.
In this staging system, chronic lymphocytic leukemia is divided into five different stages:
Stage 0: The patient has lymphocytosis with more than 5000 lymphocytes per microliter of blood but no other physical signs.
Stage I: The patient has lymphocytosis and enlarged lymph nodes. The patient does not have an enlarged liver or spleen, anemia, or low levels of platelets.
Stage II: The patient has lymphocytosis and an enlarged spleen and/or liver and may or may not have swollen lymph nodes.
Stage III: The patient has lymphocytosis and anemia. The patient may or may not have swollen lymph nodes and an enlarged liver or spleen.
Stage IV: The patient has lymphocytosis and low levels of platelets. The patient may or may not have swollen lymph nodes, an enlarged liver or spleen, or anemia.
Sometimes, doctors break these stages into “risk groups” that help them determine when to begin treatment:
This staging system classifies CLL by the number of affected lymphoid tissue groups (neck lymph nodes, underarm lymph nodes, groin lymph nodes, spleen, and liver) and by whether or not the patient has anemia (too few red blood cells) or thrombocytopenia (too few blood platelets). There are three stages: A, B, and C.
Stage A: The patient does not have anemia or low levels of platelets. Leukemia can be felt in fewer than three areas of lymph nodes (Rai stages 0, I, and II).
Stage B: The patient does not have anemia or low levels of platelets. The leukemia is in three or more areas of lymph nodes (Rai stages I and II).
Stage C: The patient has anemia and/or low levels of platelets (thrombocytopenia). Leukemia is in any number of lymph nodes (Rai stages III and IV).
In acute myeloid leukemia (AML), treatment is planned based on the subtype of AML rather than its stage. The two main systems used to classify AML subtypes are the French-American-British (FAB) classification and the newer World Health Organization (WHO) classification.
Under this classification, AML is divided into subtypes M0 through M7, based on the type of cell the leukemia develops from and how mature the cells are. This was based largely on how the leukemia cells looked under the microscope after routine staining.
Subtypes M0 through M5 all start in immature forms of white blood cells. M6 AML starts in very immature forms of red blood cells, while M7 AML starts in immature forms of cells that make platelets.
Unlike the FAB classification system, the WHO classification system takes into account many of the factors that are now known to affect the prognosis (outlook) that can better classify acute myeloid leukemia.
The WHO system divides AML into several groups, including:
In this type of blood cancer, the disease is classified by phase: chronic phase, accelerated phase, or blastic phase. These phases, along with the results from diagnostic tests, are important in planning treatment.
The number of blast cells in the blood and bone marrow and the severity of signs or symptoms determine the phase of the disease. The three phases of chronic myeloid leukemia are:
Sometimes, CML can relapse (return) after it has been treated. In relapsed CML, the number of blast cells increases after remission.
Doctors have found that cytogenetic tests, flow cytometry, and other lab tests provide more detailed information about the subtype of ALL and the patient’s prognosis than traditional staging methods. These tests help divide ALL into groups based on the gene and chromosome changes in the leukemia cells.
The WHO system divides ALL into several groups, which include:
Visit the American Cancer Society website for more details regarding B-Cell and T-Cell ALL groups.