Risk factors are patient and disease characteristics that clinical research studies have linked to better or poorer outcomes from treatment. Risk factors are also called prognostic factors. Doctors look at risk factors to try to predict how well a patient's disease will respond to treatment.
This page focuses on some of the risk factors doctors may use to plan treatment for acute lymphoblastic leukemia (ALL). For a more complete overview of ALL symptoms and treatment options, see Acute Lymphoblastic Leukemia (ALL).
Risk factors doctors may consider
Patients with low risk factors may have a good chance of reaching a long-term remission with chemotherapy. For patients with certain high risk factors, a bone marrow or cord blood transplant (also called a BMT) may offer a better chance for a long-term remission. Patients with high-risk disease should talk with their doctor about referral to a transplant doctor for consultation to see if a transplant is a good treatment option.
Age at diagnosis
Children between the ages of 1 and 9 tend to respond better to treatment than adults and children older than age 10. Children younger than one year of age at diagnosis are considered high-risk and should be referred to a transplant doctor for consultation to see if transplant is a good treatment option.
White blood cell count
A high white blood cell count at diagnosis is a high-risk factor. For children, a white blood cell count of more than 100,000 is considered high-risk. For adults, a white blood cell count of more than 30,000 to 50,000 is considered high-risk. Patients with these high-risk white blood cell counts should be referred to a transplant doctor.
Changes to the chromosomes — cytogenetic factors
Cytogenetic factors are changes in the chromosomes of the leukemia cells.
- There may be more or fewer chromosomes than normal
- Part of one chromosome may move to another (chromosome translocation)
There are many chromosome changes that can occur with ALL. Some are linked with better outcomes (low-risk changes) and others are linked with worse outcomes (high-risk changes). If you have ALL, ask your doctor to explain your cytogenetic risk factors to you.
- An example of a low-risk cytogenetic change is having more chromosomes than normal (called hyperdiploidy). This change appears in 25% of children and 7% of adults.
- An example of a high-risk cytogenetic change is the translocation between chromosomes 9 and 22. This is called the Philadelphia chromosome (or Ph+ ALL). It appears in 3% to 5% of children and 20% to 25% of adults.
- Children with Ph+ ALL or another high-risk cytogenetic change called the 11q23 rearrangement should be referred to a transplant doctor for consultation.
- Adults with Ph+ ALL or the 11q23 rearrangement or any other high-risk cytogenetic changes should be referred to a transplant doctor for consultation.
Type of ALL
- In children, having pre-B ALL or early pre-B-cell ALL are low risk factors
- In adults, T-cell ALL is a low risk factor
- In children and adults, mature B-cell (Burkitt) leukemia is a high risk factor. Children with this type of ALL should consult a transplant doctor.
Whether the leukemia has spread
Patients are at higher risk if leukemia cells appear in the testicles (for males) or in the spinal fluid (showing the disease has spread to the central nervous system). Adults whose leukemia has spread to the central nervous system or the testicles are considered high-risk and should consult a transplant doctor.
How quickly the disease responds to treatment
Children whose blood shows no leukemia cells after 7 to 14 days of induction chemotherapy have a lower risk of relapse than children who take longer to reach remission. Children who do not reach remission at all after induction chemotherapy are at high risk and should consult a transplant doctor to see if transplant is a good treatment option.
Adults who show no leukemia cells within four weeks after starting induction chemotherapy have a lower risk. Adults who do not reach a remission within four weeks or who do not reach remission at all are at high risk and should consult a transplant doctor to see if transplant is a good treatment option.
Children who reach a remission but later relapse are considered at high risk if the first remission lasts less than 18 months. These children should consult a transplant doctor to see if transplant is a good treatment option. Children who relapse more than once are also at high risk. Children in a third (or later) remission should consult a transplant doctor.
Adults are considered at high-risk after one relapse. Adults in a second (or later) remission should consult a transplant doctor.
Doctors also look at a patient's overall health when planning treatment. Patients with health problems in addition to their ALL may be unable to tolerate some treatments. Examples of other health problems include diabetes, heart disease or organ damage caused by previous chemotherapy treatments.
Talking with your doctor about risk factors
If you have ALL, ask your doctor to explain your risk factors to you. If you want more information to help you talk to your doctor about whether you should consider a transplant, you can share the referral guidelines (PDF) from the Physician section of this website with your doctor.
C. F. LeMaistre, M.D., Southwest Texas Methodist Hospital, San Antonio, Texas
Paul Shaughnessy, M.D., Texas Transplant Institute, San Antonio, Texas
Anthony S. Stein, M.D., City of Hope National Medical Center, Duarte, Calif.