Acute myelocytic leukemia following prolonged streptozotocin therapy

Biphenotypic leukemia with unusual chromosomal translocation in a patient treated for melanoma

A patient in complete remission from malignant melanoma but with refractory anemia after nitrosourea treatment developed acute biphenotypic leukemia. This disease, progression was accompanied by expansion of a cytogenetically abnormal clone. At first cytogenetic analysis, 1 year post discontinuation of chemotherapy, only 25% of the metaphases examined were hypodiploid with monosomy 7. Six months later, all of the metaphases seen were 45,XY,-7. Six months before overt acute leukemia was diagnosed, an additional chromosome abnormality emerged, t(2;3)(q31;q27). Although the translocation was present in all metaphases examined, the patient progressed into an acute leukemia with two components: one TdT-positive, Ia-positive, and the other TdT-negative, Ia-positive, monocytoid antigen-positive. This mixed leukemia was identified by double fluorescence staining for intranuclear TdT and surface labeling with a monocyte-specific monoclonal antibody.

Carcinogenicity of antineoplastic agents in man

Review of the literature shows that: Anticancer drugs are in all probability mostly also carcinogenic. Alkylating agents such as melphalan, chlorambucil and cyclophosphamide seem to lead to the highest rate of second malignancies. Second malignancies after antitumour drugs are mostly acute leukaemias. Conditions which could influence the carcinogenicity of an antitumour drug are (a) its carcinogenic potency; (b) long-term administration; (c) the total dose used and (d) long-term survival of the patient. Irradiation and chemotherapy seem to have the greatest carcinogenic potential, e.g. in malignant lymphomas. The role of immunosuppression as a co-carcinogenic factor is difficult to estimate. Although transplant patients on anticancer drugs for immunosuppression have a higher risk of reticulosarcomas, but not of solid tumours, there is no evidence to suppose that in general immunosuppression and carcinogenicity are directly related. There is no reason to abandon intensive chemotherapy regimes if they lead to significant therapeutic results on the grounds of possible carcinogenicity of these drugs.

Leukemia and preleukemia after adjuvant treatment of gastrointestinal cancer with semustine (methyl-CCNU)

We evaluated the risk of acute nonlymphocytic leukemia, acute myelodysplastic syndrome, and preleukemia in 3633 patients with gastrointestinal cancer who were treated in nine randomized clinical trials. Among 2067 patients given semustine (methyl-CCNU) as adjuvant therapy, leukemic disorders developed in 14, whereas only one leukemic disorder (acute nonlymphocytic leukemia) occurred among 1566 patients given other therapies (relative risk = 12.4; 95 per cent confidence interval = 1.7 to 250). The six-year cumulative mean risk (+/- S.E.) of acquiring a leukemic disorder after treatment with semustine was 4.0 +/- 2.2 per cent; the incidence rate was 2.3 cases per 1000 persons per year. Risk increased significantly with time after treatment. The risk of leukemic disorders did not differ according to sex, race, age at treatment, or initial tumor type, nor was it enhanced by concomitant radiotherapy or immunotherapy. In addition, no excess of acute nonlymphocytic leukemia was seen in 44,370 patients treated for gastrointestinal cancer in Connecticut during the period 1935 to 1974, before the advent of nitrosourea chemotherapy. This study provides quantitative evidence that nitrosoureas are leukemogenic in human beings and confirms previous observations that adjuvant chemotherapy with alkylating agents may increase the risk of leukemia.