PURPOSE: Radiosurgery is a promising treatment option for peripheral stage I non-small cell lung cancer (NSCLC). We report preliminary outcomes using CyberKnife with real-time tumor motion tracking.
METHODS: Twenty small (< 4 cm) peripheral inoperable stage I NSCLCpatients were treated over a 24-month period. Fiducials (3-5) were placed in or near tumors. A non-isocentric treatment plan with a 5-mm margin was generated. Patients received 42-60 Gy in 3 equal fractions. The minimum and mean 30 Gy margin on the gross tumor volume (GTV), volume of lung receiving 15 Gy (V15) and total lung volumes were calculated. CT imaging and pulmonary function testing were completed at 6 and 12 months.
RESULTS: Severe pulmonary dysfunction was the primary rationale for non-surgical treatment. The tumors’ maximum diameter ranged from 1.1 to 3.5 cm (mean =2.2 cm). The mean total dose was 53 Gy (range 42 to 60 Gy). The 30-Gy isodose contours extended a minimum of 10 mm and an average of 21 mm from the GTV. The mean percentage of total lung volume receiving 15 Gy was 7.3% (range 2.4% to 11.3%). All patients completed treatment with few side effects. Transient grade III pneumonitis was observed in 2 patients. No change was seen in the mean %predicted FEV1 at 6 and 12 months. A 10% and 15% decline in the mean %predicted DLCO was seen at 6 and 12 months, respectively. The complete and partial response rate at 12 months was 15% and 24% respectively. 61% were completely obscured by radiation fibrosis at 12 months. There has been no evidence of local or regional recurrence. At a median follow-up of 12 months, the crude survival rate is 95%, with the single death due to progressive COPD.
CONCLUSION: Stereotactic radiosurgery with real-time tumor motion tracking is a well-tolerated treatment option for inoperable peripheral Stage I NSCLC. Effective gross tumor doses and adequate margins likely contributed to the optimal early local control.
CLINICAL IMPLICATIONS: CyberKnife is a treatment option for inoperable peripheral lung tumors.
DISCLOSURE: Brian Collins, No Product/Research Disclosure Information; Consultant fee, speaker bureau, advisory committee, etc. Consultant fees and educational honorarium received from Accuray.