Sister chromatid exchange in childhood malignancies.

Sister chromatid exchange studies were conducted in 53 children with malignant diseases. Children with acute lymphoid leukemia in long remission, already off chemotherapy or on maintenance therapy, had normal SCE values, whereas those receiving intensive cytostatic therapy showed elevated levels. SCE values were primarily related to the time and dose of preceding cytostatic drug therapy, and the subsequent relapse might influence the SCE frequencies, independently from the cytostatic therapy.