Clinical radiation pneumonitis and radiographic changes after thoracic radiation therapy for lung carcinoma.

Background: The authors attempted to determine the incidence of and risk factors for clinical radiation pneumonitis in patients treated for lung carcinoma. They also sought to describe the corresponding posttreatment radiographic changes.

Methods: Between 1989-1993, 83 patients received curative radiation therapy for lung carcinoma. Of these, 39 patients were treated with definitive radiation therapy, and 44 patients were treated with adjuvant radiation therapy after surgical resection. The median radiation therapy dose was 54 gray (Gy), and the median treatment area was 182 cm2. Chest radiographs obtained after radiation therapy were reviewed and scored for margin definition, volume loss, and texture quality.

Results: A total of 17 patients (20%) developed clinical radiation pneumonitis (CRP). The median radiation therapy dose for the CRP cohort was 54 Gy, and the median treatment volume was 193 cm2. The median time to onset of symptoms was 3 weeks after radiation therapy, and the median duration of symptoms was 10 weeks. Of the 15 evaluable patients, symptoms resolved for 9 patients, improved but persisted for 4 patients, and CRP was fatal for 2 patients. The incidence of CRP was increased for patients with low performance status, comorbid lung disease, smoking history, low pulmonary function tests, and for those patients who did not undergo a surgical resection. Posttreatment radiographic changes were common and progressed with time. Radiographic changes were more pronounced in the CRP cohort, and extended outside the radiation therapy treatment field in the majority of patients (67%).

Conclusions: Clinical radiation pneumonitis developed in 20% of lung carcinoma patients. Risk factors included low performance status, comorbid lung disease, smoking history, low pulmonary function tests, and the absence of a surgical resection. Posttreatment radiograph changes were common and progressed with time, and typically were not confined to the radiation therapy treatment field.