Relapse

Updated March 27, 2026

What is a relapse?

When patients who have been treated for their acute lymphoblastic leukemia achieve remission but later show a new increase in the number of leukemic cells in their body, they are said to have relapsed. For children with acute lymphoblastic leukemia, only 15–20% will experience a relapse; whereas in adult patients, it can be as high as 60–70%.

When does this occur?

A relapse can occur at any time, but it is more likely to happen within 2 years of the first treatment. Symptoms of a relapse are similar to those experienced with newly diagnosed acute lymphoblastic leukemia. A list of these symptoms can be found here.

Diagnosis of a relapse is performed using the same tests that your doctor or healthcare provider used to initially diagnose your acute lymphoblastic leukemia. This list can be found here.

Why do patients relapse?

Certain factors, such as age, presence of genetic changes, and specific type of acute lymphoblastic leukemia, can all increase your risk of relapse. More can be found about this subject on the prognosis page.

How is a relapse treated?

A patient with acute lymphoblastic leukemia who has relapsed can still be cured, despite their increasing number of leukemic cells following initial treatment.

As with initial treatment, the main choice for treating relapse is also chemotherapy. The same chemotherapy agents given previously may be used again, or your doctor may try a different drug or a combination of agents. If your acute lymphoblastic leukemia is difficult to treat, you may be offered a stem cell transplant. More information on possible therapy options is available on our treatment page.

If a treatment does not yield remission with a certain drug, patients are said to be refractory to this drug. In this case, a different treatment should be given.

References

1. Leukaemia Care. Relapse in acute lymphoblastic leukaemia (ALL) https://www.leukaemiacare.org.uk/about-leukaemia/types/acute-lymphoblastic-leukaemia-all/relapsed-or-refractory-acute-lymphoblastic-leukaemia-all/. Updated Jan 2026. Accessed Mar 27, 2026.