PURPOSE: To report early lung function and survival outcomes following radical robotic radiosurgery for inoperable peripheral stage IA non-small cell lung cancer (NSCLC) patients.
METHODS: Inoperable patients with biopsy-proven peripheral stage IA NSCLC were enrolled. Total doses ranging from 42 to 60 Gray (Gy) were prescribed. The 30-Gy isodose contour was extended at least 1 cm from the tumor to eradicate microscopic disease. Treatment was delivered in 3 equal fractions over a 2 week period using the CyberKnife. Routine pulmonary function tests were completed at 1 year.
RESULTS: Twenty predominately former smokers (90%) with a mean age of 75 years and an average maximum tumor diameter of 2.2 cm (range, 1.4 - 3.0 cm) were treated. The mean baseline forced expiratory volume in 1 second (FEV1) was 1.06 L or 54% predicted (range, 21 - 84%). The mean baseline diffusion capacity for carbon monoxide (DLCO) was 11.0 mg/min/mmHg or 58% predicted (range, 47 - 83%). An average total dose of 53 Gy was delivered to the 5 mm tumor margin, resulting in 7.3% of the mean total lung volume receiving a potentially injurious dose of 15 Gy or more (range, 2.4% to 11.3%). The mean percent predicted DLCO declined by 11% (range, 0 to 33%) at 1 year. At a median follow-up of 30 months, 17 patients remain alive without evidence of disease. Deaths at 9, 18 and 24 months were the result of progressive lung dysfunction in patients with pretreatment FEV1 values less than 30% predicted.
CONCLUSION: Radical robotic radiosurgery results in exceptional tumor control and survival in inoperable patients with peripheral stage IA NSCLC. However, survival remains disappointing in patients with very severe COPD.
CLINICAL IMPLICATIONS: Optimizing survival outcomes in patients with peripheral stage IA NSCLC and very severe COPD (FEV1<30% predicted) may require more conservative CyberKnife treatment approaches.
DISCLOSURE: Eric Anderson, Consultant fee, speaker bureau, advisory committee, etc. Honoraria for educational lectures from Accuray.; No Product/Research Disclosure Information