Chronic lymphocytic leukemia (CLL) is a slow-growing disease. People can live with CLL for many years. Researchers estimate how long people with CLL live using statistics called survival rates. You may do better or worse than these predicted rates depending on whether you have certain prognostic factors that raise or lower your risk of severe disease.
CLL outlook is often measured with a number called five-year survival. This doesn’t mean that you only have five years to live. Instead, it is a count of how many people are predicted to live for five years or more after being diagnosed.
The five-year survival rate for CLL in the United States is 85.7 percent. This means that, for every 100 people diagnosed with CLL now, about 86 people are expected to be alive in five years. This survival rate also applies to people with small lymphocytic lymphoma (SLL). SLL and CLL are very similar diseases and develop from the same blood cells. CLL leads to cancer cells in the blood and SLL leads to cancer cells in the lymphatic system.
Treatment options for CLL are constantly improving. Because the five-year survival rate is based on past information, it may not reflect newer, better methods. People being diagnosed with CLL now may have an even better prognosis than is reflected in these statistics.
Survival rates don’t tell you what your outcome will be. Survival rates are based on data from large groups of people. Your outlook may be better or worse depending on your characteristics. If you are interested in learning more about your prognosis, talk to your doctor.
Many factors can lead to a better or worse outlook for people with CLL. These are known as prognostic factors. If you have favorable prognostic factors, you are more likely to have a longer survival time. On the other hand, having negative prognostic factors means that you may have a worse outlook.
Older age often leads to a worse CLL prognosis. In one set of studies, researchers found the following:
One reason that older adults often have a worse outlook is that they can’t undergo certain therapies. Some cancer treatments lead to better outcomes for young people but cause too many side effects in older people.
One of the factors in determining CLL outlook is the stage of the disease. The stage describes where in the body leukemia cells can be found and whether cancer has spread.
In America, doctors often use the Rai staging system. Under this system, doctors measure levels of lymphocytes (white blood cells), red blood cells, and platelets. They also consider whether the lymph nodes, spleen, or liver are enlarged. Based on these features, doctors assign each CLL case a number between 0 and 4. People with early-stage CLL usually live longer than those with later-stage disease.
Cancer develops when a cell’s genes become damaged and undergo changes. Doctors are able to find gene changes in more than 80 percent of people with CLL. Some of these changes lead to more aggressive leukemia, and others are linked to slower-growing CLL.
Some people with CLL have mutations in a gene called immunoglobulin heavy chain variable region (IGHV). People with mutations often have a better outlook — treatment is more effective, and they have longer survival rates. IGHV mutations also affect how likely a person is to experience complete remission or the absence of disease signs and symptoms. In one study, 82 percent of people with mutated IGHV were in complete remission after six years. However, only 47 percent of people with normal IGHV were in complete remission at this time.
Additional gene mutations are also linked with a poor prognosis. People with changes in the TP53, NOTCH1, ATM, BIRC3, and SF3B1 genes are more likely to be resistant to treatment. Some studies have found that these changes can lead to worse outcomes, although this is still being studied.
Cytogenetic tests can show chromosome changes. Chromosomes are large pieces of DNA that contain genes. Sometimes, chromosomes within cancer cells contain deletions. Some of these abnormalities serve as prognostic factors in CLL. Changes called del(17p) and del(11q) — deletions in chromosomes 17 or 11 — are linked with a worse prognosis. On the other hand, deletion of part of chromosome 13 can be a sign of a favorable prognosis.
Tests like flow cytometry can read the proteins that are found on the surface of cancer cells. When many of the cells contain the proteins ZAP-70 or CD38, a person’s prognosis may be worse.
Blood tests show that some people with CLL have high levels of certain types of lymphocytes, such as prolymphocytes. People with these cells are more likely to have their CLL transform into another, more severe type of cancer such as prolymphocytic leukemia or diffuse large B-cell lymphoma (DLBCL).
Doctors often measure lymphocyte levels regularly throughout a person’s disease. If the lymphocyte count increases quickly, it can be a sign of more aggressive CLL. A lymphocyte count that doubles itself in less than a year may indicate a worse outlook.
The most common leukemia biomarkers are CD (cluster of differentiation) markers. They are an extremely diverse series of membrane proteins mostly expressed on the leukocyte surface. CD markers are useful for classifying white blood cells (WBCs) and are very important for diagnosing lymphoma and leukemia. Certain molecules in the blood can serve as markers of severe leukemia. These molecules can be measured with blood tests.
Doctors sometimes predict outcomes with a tool called the CLL International Prognostic Index (CLL-IPI). The CLL-IPI takes into account certain risk factors and divides people with CLL into four risk groups. The prognostic index considers age, stage, changes in the TP53 and IGHV genes, and levels of beta-2-microglobulin. Each of these prognostic factors is given a certain number of points, and then the points are added up into one final score. This calculation leads to the following groups:
These risk groups give you a clue about not only your prognosis but also about what treatment options may be best. People in the lowest-risk group may not need any treatment at all, whereas people in the highest-risk group may want to try newer therapies or take part in clinical trials.
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