Purpose: To estimate the risk of secondary leukemia as a function of the dose of epipodophyllotoxins and anthracyclines.
Methods: We conducted a case-control study of the risk of secondary leukemia or myelodysplasia after a solid tumor in childhood within the Société Française d'Oncologie Pédiatrique, including 61 patients with leukemia matched with 196 controls. The characteristics of the first cancer, the patient's family history of cancer, and the treatment (type, cumulative dose of chemotherapy, schedule of etoposide administration, and radiation dose delivered to active bone marrow) were compared in the two groups.
Results: Only two factors were found to increase the risk of leukemia in multivariate analysis, namely, the type of the first tumor, with an excess risk in patients with Hodgkin's disease (relative risk 6.4; 95% confidence interval [CI], 1.6 to 24) or osteosarcoma (relative risk 5; 95% CI, 1.3 to 19), and exposure to epipodophyllotoxins and anthracyclines. The risk of leukemia increased regularly with the cumulative dose of etoposide. In summary, patients who received between 1.2 and 6 g/m(2) of epipodophyllotoxins or more than 170 mg/m(2) of anthracyclines had a seven-fold higher risk (95% CI, 2.6 to 19) compared with patients who received lower doses or none of these drugs. The risk of leukemia in patients who received more than 6 g/m(2) of epipodophyllotoxins was multiplied by 197 (95% CI, 19 to 2,058). The risk of leukemia was not increased by exposure to alkylating agents or radiotherapy.
Conclusion: Both epipodophyllotoxins and anthracyclines increase the risk of secondary leukemia. The current challenge is to minimize the mutagenic effects of these drugs by diminishing cumulative doses without losing the therapeutic benefits.