To determine the short-term effects of stereotactic body radiotherapy on pulmonary function in patients with medically unresectable stage 1 non-small cell lung cancer (NSCLC).
We recently completed a phase 1 study of stereotactic body radiotherapy which enrolled patients with medically unresectable stage 1 NSCLC. The dose-limiting toxicity was not reached, but the study was halted at a level of 2000cGy/fraction. Subsequently a phase II study was initiated using 2000cGy/fraction times 3 fractions (6000 cGy total) for patients with medically unresectable stage 1 NSCLC. Baseline pulmonary function tests were performed (FEV1, FVC, DLCOand pO2) at baseline, 6 weeks and then at 3 months.
At this time a total of 13 patients have completed therapy and the initial 3-month follow-up period. One patient suffered a grade 2 pulmonary toxicity (pneumonitis with < 12% change in pulmonary function), which required hospitalization. Baseline pulmonary function values were: FEV1 1.2 liters, FVC 2.4 liters, DLCO 12.4 and pO2 74. At 6 weeks values were: FEV1 1.2, FVC 2.5, DLCO 10.9 and pO2 73. At 3 months post radiotherapy values were: FEV1 1.1, FVC 2.3, DLCO 10.2 and pO2 72. There was no significant decrease in FEV1, FVC or p02, but the DLCO decreased by 18% at 3 months.CONCLUSIONS: In this population of patients with poor pulmonary function, high dose stereotactic body radiotherapy for medically unresectable stage 1 NSCLC did not decrease short-term spirometry or pO2. There was evidence of a decrease in DLCO at 6 weeks and 3 months.
Frail patients with medically unresectable stage 1 NSCLC appear to tolerate high doses of targeted radiotherapy. Further study of pulmonary function long-term is required in this population.
M.D. Williams, None.