Effect of postoperative radiotherapy on changes in pulmonary function in patients with stage II and IIIA lung carcinoma.

To assess the pulmonary tolerance to postoperative radiotherapy (RT) in patients with resected lung carcinoma, a prospective study was begun in January 1977, which consisted of (a) initial pulmonary function test (PFT) and arterial blood gases (ABG) at 1 month after surgery, and before beginning of postoperative RT, and (b) follow-up PFT and ABG 1 year after postoperative RT and then every year thereafter. As of December 1987, 137 patients have been enrolled into this study, and 71 patients who were free of recurrence were subjected to the follow-up PFT and ABG. The remaining 66 patients were unable to complete the follow-up studies because of recurrent carcinoma in 60, refusal to participate in the study in 5 patients even in the absence of significant respiratory symptoms, and progressive asbestos-related pleural thickening in 1 patient. The patient characteristics were as follows: Age ranged from 27 to 79 years with the median of 59 years; sex ratio was 1.4 to 1 for male to female; surgical procedures included lobectomy in 49 and pneumonectomy in 22 patients; tumor extent consisted of Stages T1-T2N1M0 in 44, T1-T2N2M0 in 9, and T3N0-N2M0 in 18 patients, respectively. Histologic types included squamous cell carcinoma in 26, adenocarcinoma in 42, small cell carcinoma in 1, and large cell carcinoma in 2 patients. Target volume for RT included the ipsilateral hilum, the mediastinum, and the thoracic inlet including both supraclavicular fossae. A total dose of 54 Gy was delivered in 1.8 Gy of daily fractions, 5 days per week over a period of 6 weeks. Contrary to expectation, there were minor changes in PFT indices in both lobectomy and pneumonectomy patients. The follow-up PFT in the lobectomy group showed small -3% to +2% changes in mean values of ventilatory indices, lung volume, and ABG. The follow-up PFT in the pneumonectomy group also showed small -9% to +13% changes in mean values of ventilatory indices, lung volume, and ABG. Sixteen patients have had more than one PFT during the follow-up period (2 years to 10 years), and there was no significant long term adverse effect of RT on PFT in this subset of patients. Lung scans assessing regional function, which were available in six patients, were not helpful in predicting changes in PFT indices as a result of postoperative RT.