Acute leukemia following treatment of malignant glioma.

We report two patients with acute myeloid leukemia (AML) following therapy for malignant glioma; one was a young women treated heavily with alkylating agents for glioblastoma and the other a young man treated with high doses of procarbazine, lomustine, and vincristine (PCV) for anaplastic astrocytoma. We found 26 other examples of therapy related leukemia in adult and pediatric brain tumor patients. Including our two, there were 12 patients with malignant glioma; median interval from treatment to diagnosis of AML was 31 months. Nine adult malignant glioma patients all received nitrosoureas, some as the sole form of chemotherapy. No definite cases occurred after radiotherapy alone. Based upon analogy with other cancers, the cumulative dose of chemotherapy, especially alkylating agents, is the major risk factor for development of secondary AML. Agents implicated include carmustine (BCNU), lomustine (CCNU), and procarbazine. Conventional radiotherapy appears not to confer additional risk. Progressive macrocytosis, early dose reductions for thrombocytopenia, and refractory anemia may provide early diagnostic clues. Current glioma therapy is leukemogenic but the number of patients who survive the interval required to induce AML is small; nevertheless, the identification of chemosensitive types of glioma, and subgroups of patients who derive the most benefit from chemotherapy, may result in increasing numbers of patients at risk of long term complications. If regimens such as PCV continue to prove valuable in neurooncology the risk of leukemia will require integration into the clinical decision process. A search for more effective therapy with minimal mutagenicity remains critical.