Treatment for Radiation Pneumonitis

Virna Ignacio Almuete, RPh


January 06, 2003


A 68-year-old woman was diagnosed with stage IIIA lung adenocarcinoma 2.5 years ago. She underwent tumor resection, radiation, and chemotherapy. She is doing well, except for a constant cough, which is attributed to postradiation pneumonitis. Prednisone 10 mg alleviates the cough, but the side effects are prohibitive. Do you have any other suggestions?

Response from Virna Ignacio Almuete, RPh

Radiation pneumonitis is an inflammatory process affecting the lungs following radiation therapy. This condition develops in 5% to 15% of lung cancer patients receiving high-dose external-beam radiation. Factors that affect the risk of damage to lung tissue include: the volume of lung included in the field of radiation, the total dose and the fraction of that dose, individual susceptibility to radiation, previous irradiation, low performance status, concomitant chemotherapy, and abrupt steroid withdrawal.

The pathophysiology of radiation pneumonitis is described as 2 distinct mechanisms. The first is classical radiation pneumonitis. Injury to capillary endothelial and epithelial cells of the lung from the radiation results in an acute alveolitis. The inflammatory process leads to pulmonary fibrosis and is confined to the field of radiation. The second mechanism is sporadic radiation pneumonitis or an "out-of-field" response. This is thought to be an immunologically mediated process resulting in bilateral lymphocytic alveolitis.

Although pathologic changes in lung tissue occur in the initial 24-48 hours after radiation, those changes are undetectable clinically and radiologically. Symptoms of acute radiation pneumonitis develop 1-6 months after completion of therapy. Symptoms can include dyspnea, cough, pinkish-tinged sputum, and fever. Severe reactions can result in dyspnea, pleuritic chest pain, hemoptysis, acute respiratory distress, and death. The characteristic feature of radiation pneumonitis is a diffuse infiltrate corresponding to a previous radiation treatment field.

Corticosteroids are commonly used for the treatment of radiation pneumonitis. Prednisone is started at 1 mg/kg/day upon diagnosis and is continued for several weeks and then tapered slowly. Other agents that have been used for treatment of radiation pneumonitis include azathioprine and cyclosporin A.


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