Radiation-induced and chemotherapy-induced pulmonary injury

The management of cancer has continued to advance with the development of new chemotherapeutic agents and improved techniques of radiation therapy. Although new therapeutic approaches have improved survival in cancer patients, each form of intervention has the potential to produce adverse effects on normal host tissues. Some of these toxicities may be accentuated with combined modality therapy. The use of chemotherapy and radiation therapy, alone or combined, can be associated with clinically significant pulmonary toxicity. The pulmonary toxic effects of chemotherapy can be divided into (1) early onset, resulting in interstitial lung injury, and (2) late onset, with pulmonary fibrosis as a sequela. These toxic effects are frequently dose related but may be enhanced by radiation therapy. Similar to chemotherapy, radiation can produce acute or chronic lung injury depending on dose rate, duration, preexisting lung disease, and concomitant steroid use. Acute radiation injury typically occurs 2 weeks to 3 months after treatment and is usually limited to the irradiated field. Mild injury often resolves without treatment, whereas more serious injury results in fibrosis 6 to 12 months after treatment. Histopathologic evaluation of acute lung injury is no different from drug-induced injury, and damage to vascular endothelial cells and alveolar lining cells is seen. This article reviews and provides an update on the clinically important chemotherapy and radiation-induced pulmonary injuries, the pathologic mechanisms, where known, and the treatment advances that have occurred in this field.