The topic of “cure” for leukemia is a complicated one – there is no known absolute cure for leukemia in the way we understand cures for common diseases.
Typically, a patient is considered “cured” of leukemia when they achieve a certain amount of time after first reaching remission. Statistically, every year a patient stays in remission reduces their chances of relapse significantly, and after 10 years of continuous remission there is a very small chance of relapse. Most hospitals will be comfortable calling the patient “cured” at this point.
Roughly 98% of children diagnosed with ALL achieve remission within the first several weeks, and about 90% of them will eventually be considered cured.