Cytogenetic studies of bone marrow in breast cancer patients after adjuvant chemotherapy.

Bone marrow chromosome studies were done on three patients who developed acute nonlymphocytic leukemia 5 to 19 months after completion of adjuvant chemotherapy for breast cancer, and on 17 breast cancer patients without hematologic disease 2 to 30 months after similar adjuvant therapy. Clones of cells with multiple cytogenetic abnormalities were demonstrated in two of the three leukemic patients. No chromosomally abnormal clones or evidence of increased chromosome damage was found in the 17 nonleukemic individuals. Although leukemias induced by chemotherapy, and particularly by alkylating agents, typically show multiple cytogenetic alterations, it appears that patients recently exposed to these agents, but without obvious hematopoietic disorders, do not have a high frequency of aberrant marrow clones. Additional approaches may be needed for early identification of patients at increased risk for chemotherapy-induced leukemia.