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.