Pulmonary function testing after stereotactic body radiotherapy to the lung

Surgical resection remains the standard of care for operable early-stage non-small-cell lung cancer (NSCLC). However, some patients are not fit for surgery because of comorbidites such as chronic obstructive pulmonary disease (COPD) and other medical conditions. We aimed to evaluate pulmonary function and tumor volume before and after stereotactic body radiotherapy (SBRT) for patients with and without COPD in early-stage lung cancer.

A review of prospectively collected data of Stage I and II lung cancers, all treated with SBRT, was performed. The total SBRT treatment was 60 Gy administered in three 20 Gy fractions. The patients were analyzed based on their COPD status, using their pretreatment pulmonary function test cutoffs as established by the American Thoracic Society guidelines (forced expiratory volume [FEV]% ≤ 50% predicted, FEV%/forced vital capacity [FVC]% ≤ 70%). Changes in tumor volume were also assessed by computed tomography.

Of a total of 30 patients with Stage I and II lung cancer, there were 7 patients in the COPD group (4 men, 3 women), and 23 in t he No-COPD group (9 men, 14 women). At a mean follow-up time of 4 months, for the COPD and No-COPD patients, pretreatment and posttreatment FEV% was similar: 39 ± 5 vs. 40 ± 9 (p = 0.4) and 77 ± 0.5 vs. 73 ± 24 (p = 0.9), respectively. The diffusing capacity of the lungs for carbon monoxide (DL(CO)) did significantly increase for the No-COPD group after SBRT treatment: 60 ± 24 vs. 69 ± 22 (p = 0.022); however, DL(CO) was unchanged for the COPD group: 49 ± 13 vs. 50 ± 14 (p = 0.8). Although pretreatment tumor volume was comparable for both groups, tumor volume significantly shrank in the No-COPD group from 19 ± 24 to 9 ± 16 (p < 0.001), and there was a trend in the COPD patients from 12 ± 9 to 6 ± 5 (p = 0.06).

SBRT did not seem to have an effect on FEV(1) and FVC, but it shrank tumor volume and improved DL(CO) for patients without COPD.