To examine the effect of baseline forced expiratory volume in 1 second (FEV(1)) and diffusion capacity for carbon monoxide (Dl(co)) on posttreatment survival and pulmonary function decrease after stereotactic body radiotherapy (SBRT) for patients with early-stage non-small-cell lung cancer (NSCLC).

Seventy medically inoperable patients with Stage I NSCLC were treated with definitive SBRT to a dose of 6,000 (Stage IA) or 6,600 cGy (Stage IB), given in three equal fractions. Baseline and serial posttreatment pulmonary function data were collected.

Median age was 70.5 years, and median follow-up was 2.17 years. Median pretreatment FEV(1) and Dl(co) were 1.05 L and 10.06 mg/min/mm Hg, respectively. There was no significant decrease in survival in patients with baseline FEV(1) and Dl(co) less than the median value and less than the lowest quartile, whereas patients with values greater than the highest quartile of baseline FEV(1) had significantly inferior survival. There was no significant effect of pretreatment FEV(1) or Dl(co) on posttreatment levels. There was a statistically significant decrease in Dl(co) of 1.11 mg/min/mm Hg/y.

Poor baseline pulmonary function did not predict decreased survival or pulmonary function after treatment. A statistically significant decrease in Dl(co) after treatment was seen, similar to decreases seen in studies delivering standard thoracic radiotherapy. We conclude that low pretreatment FEV(1) and/or Dl(co) alone should not be used to exclude patients with NSCLC from treatment with SBRT.