Radical cyberknife radiosurgery with tumor tracking: an effective treatment for inoperable small peripheral stage I non-small cell lung cancer

Abstract

ObjectiveCurative surgery is not an option for many patients with clinical stage I non-small-cell lung carcinoma (NSCLC), but radical radiosurgery may be effective.MethodsInoperable patients with small peripheral clinical stage I NSCLC were enrolled in this study. Three-to-five fiducial markers were implanted in or near tumors under CT guidance. Gross tumor volumes (GTVs) were contoured using lung windows. The GTV margin was expanded by 5 mm to establish the planning treatment volume (PTV). A dose of 42–60 Gy was delivered to the PTV in 3 equal fractions in less than 2 weeks using the CyberKnife radiosurgery system. The 30-Gy isodose contour extended at least 1 cm from the GTV. Physical examination, CT imaging and pulmonary function testing were completed at 6 months intervals for three years following treatment.ResultsTwenty patients with an average maximum tumor diameter of 2.2 cm (range, 1.1 – 3.5 cm) and a mean FEV1 of 1.08 liters (range, 0.53 – 1.71 L) were treated. Pneumothorax requiring tube thoracostomy occurred following CT-guided fiducial placement in 25% of the patients. All patients completed treatment with few acute side effects and no procedure-related mortality. Transient chest wall discomfort developed in 8 of the 12 patients with lesions within 5 mm of the pleura. The mean percentage of the total lung volume receiving a minimum of 15 Gy was 7.3% (range, 2.4% to 11.3%). One patient who received concurrent gefitinib developed short-lived, grade III radiation pneumonitis. The mean percent predicted DLCO decreased by 9% and 11% at 6 and 12 months, respectively. There were no local failures, regional lymph node recurrences or distant metastases. With a median follow-up of 25 months for the surviving patients, Kaplan-Meier overall survival estimate at 2 years was 87%, with deaths due to COPD progression.ConclusionRadical CyberKnife radiosurgery is a well-tolerated treatment option for inoperable patients with small, peripheral stage I NSCLC. Effective doses and adequate margins are likely to have contributed to the optimal early local control seen in this study.

The CyberKnife radiosurgery system for lung cancer

“…Whyte et al reported three patients with pneumothoraces; two were managed expectantly but one required chest tube placement [28]. Collins et al and Pennathur et al reported a pneumothorax requiring tube thoracostomy in 25 and 28% of their patients, respectively [29,30].…”

Lung segmentectomy: does it offer a real functional benefit over lobectomy?

“…No proper comparison of SABR and segmentectomy functional consequences can be performed because of the lack of randomised trials. Several studies report PFT measured before and after SABR, but a comparison with surgical series is hazardous because of strong differences in patient characteristics ( patients in SABR studies are older and have more degraded lung function) and study design [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. The SABR PFT results suggest that the mean loss of lung function may be lower after SABR than after segmentectomy, but this needs to be confirmed.…”

Advantages of CyberKnife for inoperable stage I peripheral non-small-cell lung cancer compared to three-dimensional conformal radiotherapy

“…CK treatment has been shown to be very effective for stage Ⅰ NSCLC in several studies published over the last few years (3,4,6,12,13).…”

“…All the stage I NSCLC patients were implanted using fiducial markers with the Synchrony ® Respiratory Motion Tracking system (6). Under conscious sedation and local anesthesia, 3-5 gold fiducials measuring 0.8 mm in diameter by 3 mm in length (Civco Medical Solutions, Orange City, IA, USA) were placed with adequate spacing (1-2 cm) in or near tumours under CT guidance (7,8).…”