CLL / SLL Staging and Other Prognostic Factors
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For most cancers, staging is the process of determining and characterizing how much a cancer has spread. Identifying the stage, or level of progress can often be useful because it can help guide treatment and determine a person’s prognosis (outlook). Most types of cancer are staged based on the size of the tumor and how far the cancer has spread.
Chronic lymphocytic leukemia (CLL) does not typically form tumors, but rather it presents in the bone marrow, blood, and lymph nodes. In some cases, by the time it is discovered, it has also spread to other organs such as the spleen, liver, and lymph nodes. Because of this, the outlook for a person with CLL may depend on other information, such as all the lab test results. Imaging such as CT or PET scan at the time of diagnosis is most often not necessary in CLL.
In the United States, the most commonly used clinical staging system for chronic lymphocytic leukemia (CLL) is the Rai staging system developed by Dr. Kanti Rai in 1975. Rai staging is based simply on blood tests and physical exams (no imaging tests).
The Rai system divides CLL into 5 stages:
| Rai stage 0: | Lymphocytosis (high blood count of lymphocytes) and no enlargement of the lymph nodes, spleen, or liver, and with near normal red blood cell and platelet counts. |
| Rai stage 1: | Lymphocytosis plus enlarged lympg nodes. the spleen and liver are not enlarged, and the red blood cell and platelet counts are normal or only slightly low. |
| Rai stage II: | Lymphocytosis plus an enlarged spleen (and possibly an enlared liver), with or without enlarged lymph nodes. The red blood cell and platelet counts are normal or only slightly low. |
| Rai stage III: | Lymphocytosis plus anemia (too few red blood cells), with or without enlarged lymph nodes, spleen, or liver. Platelet counts are near normal. |
| Rai stage IV: | Lymphocytosis pluc thrombocytopenia (too few platelets), with or without anemia, enlarged lymph noeds, spleen, or liver. |
Decades later, physicians still use the Rai stages as a way of describing the level of risk from CLL for each patient. The level of risk helps to determine the best CLL management when used with other newer prognostic factors.
- Stage 0 is low-risk.
- Stages I and II are intermediate-risk.
- Stages III and IV are high-risk.
Staging in CLL / SLL should not use the Ann Arbor staging system, which would automatically classify all CLL as stage IV because all cases of CLL have tumor cells in the bone marrow.
Along with the staging, there are many other factors that help predict a person’s outlook. These factors are sometimes taken into account when looking at possible treatment options. Factors that tend to be linked with shorter survival times are called adverse prognostic factors. Those that predict longer survival are favorable prognostic factors.
Minimum testing should include FISH, TP53 testing, and IgHV mutation. FISH and TP53 can change over time or with treatment, so they must be retested before each and every new treatment.
Adverse Prognostic Factors
- Deletions of chromosomes 17p or 11q. These are found by Fluorescence In Situ Hybridization (FISH) testing that can determine the status of specific CLL chromosomes in the blood, bone marrow, or lymph nodes.
- TP53 gene mutation is usually found by next-generation gene sequencing. TP53 is on the short arm of chromosome 17 (17p) so when it is deleted, TP53 is nonfunctional. These two, 17p deletion and TP53 are critical predictive risk factors in deciding the best treatment
- High blood levels of certain substances, such as beta-2-microglobulin (B2M)
- If the lymphocyte count doubles in less than 6 months (Lymphocyte doubling time or LDT)
- More than 20% of CLL cells containing ZAP-70 or more than 30% containing CD38
- Unmutated IgHV gene
- Complex Karyotype (multiple changes in the CLL genetic material)
- More widespread bone marrow involvement
- Advanced age and/or male gender
Favorable Prognostic Factors
- Non-diffuse (nodular or interstitial) pattern of bone marrow involvement
- Deletion 13q with no other chromosome abnormalities found by FISH
- Mutated IgHV gene
Please note that this is a partial list of prognostic factors. Some factors become obsolete due to new therapies and diagnostic tools and are replaced or supplemented by newer factors.
Also remember that while these factors may reliably predict for a group of patients, they do not for any one individual. Every person’s CLL or SLL is slightly different.
Summary
All these factors and staging are becoming less “prognostic” in the era of new therapies as many new therapies are agnostic to what would be unfavorable factors with chemo-immunotherapy.
They might be better used in guiding therapy choices.
