Baseline Pulmonary Function as a Predictor for Survival and Decline in Pulmonary Function Over Time in Patients Undergoing Stereotactic Body Radiotherapy for the Treatment of Stage I Non–Small-Cell Lung Cancer

Purpose

To examine the effect of baseline forced expiratory volume in 1 second (FEV₁) 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).

Methods and Materials

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.

Results

Median age was 70.5 years, and median follow-up was 2.17 years. Median pretreatment FEV₁ 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 FEV₁ 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 FEV₁ had significantly inferior survival. There was no significant effect of pretreatment FEV₁ or Dl_co on posttreatment levels. There was a statistically significant decrease in Dl_co of 1.11 mg/min/mm Hg/y.

Conclusions

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 FEV₁ and/or Dl_co alone should not be used to exclude patients with NSCLC from treatment with SBRT.

Stereotactic body radiotherapy, Non–small-cell lung cancer, Pulmonary function, Toxicity