Late effects of therapeutic irradiation on the skeleton and bone marrow.

Sequelae in the skeleton and bone marrow can be important late consequences for survivors following radiation therapy of cancer. Skeletal sequelae of radiation therapy often are predictable, although they may not be avoidable. The growth suppressive effects of therapeutic irradiation may occur in any bone, but most often are noted in the spine after doses in excess of 2000 rads. Mature bone and cartilage may be devitalized by irradiation without clinical consequence until stressed. Although malignant tumors may arise in irradiated bone and cartilage, the risk is minimal and is readily accepted in modern-day radiation oncology. Radiation-induced suppression of bone marrow function usually is of immediate rather than late consequence; however, functional recovery after therapeutic irradiation, while prolonged, is more complete than formerly thought. Leukemia rarely develops secondary to therapeutic irradiation.