Radiation and chemical injury in the bone marrow.

Hematopoietic system toxicity is a major limiting factor in the use of aggressive combined modality therapy in the treatment of malignant disease. In this review, the known drug-x-ray interactions using tissue culture systems are extended to the bone marrow compartment. Two hypotheses prevail for late bone marrow failure: (1) stromal damage to the vasculature with subsequent fibrosis and (2) irreversible stem cell depletion in the irradiated site. Clinical extensions of the experimental data for bone marrow kinetics in the animal model have not proven successful to date. The future strategies for therapy of malignancies in which both radiation and chemotherapy are employed may require dose modification or treatment planning to limit bone marrow toxicity.