CyberKnife with Tumor Tracking: An Effective Treatment for High-Risk Surgical Patients with Stage I Non-Small Cell Lung Cancer

Viola J Chen,Jennifer Rabin,Brian T Collins,Deepa Subramaniam,Sean P Collins,Saloomeh Vahdat,Filip Banovac,Eric Oermann,Xia Yu,Eric Anderson,Simeng Suy

doi:10.3389/fonc.2012.00009

Viola J Chen, Jennifer Rabin + Show 9 more

Open Access

https://doi.org/10.3389/fonc.2012.00009

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Abstract

Published data suggests that wedge resection for stage I non-small cell lung cancer (NSCLC) is associated with improved overall survival compared to stereotactic body radiation therapy. We report CyberKnife outcomes for high-risk surgical patients with biopsy-proven stage I NSCLC. PET/CT imaging was completed for staging. Three-to-five gold fiducial markers were implanted in or near tumors to serve as targeting references. Gross tumor volumes (GTVs) were contoured using lung windows; the margins were expanded by 5 mm to establish the planning treatment volume (PTV). Treatment plans were designed using a mean of 156 pencil beams. Doses delivered to the PTV ranged from 42 to 60 Gy in three fractions. The 30 Gy isodose contour extended at least 1 cm from the GTV to eradicate microscopic disease. Treatments were delivered using the CyberKnife system with tumor tracking. Examination and PET/CT imaging occurred at 3 month follow-up intervals. Forty patients (median age 76) with a median maximum tumor diameter of 2.6 cm (range, 1.4–5.0 cm) and a mean post-bronchodilator percent predicted forced expiratory volume in 1 s (FEV1) of 57% (range, 21–111%) were treated. A median dose of 48 Gy was delivered to the PTV over 3–13 days (median, 7 days). The 30 Gy isodose contour extended a mean 1.9 cm from the GTV. At a median 44 months (range, 12–72 months) follow-up, the 3 year Kaplan–Meier locoregional control and overall survival estimates compare favorably with contemporary wedge resection outcomes at 91 and 75%, respectively. CyberKnife is an effective treatment approach for stage I NSCLC that is similar to wedge resection, eradicating tumors with 1–2 cm margins in order to preserve lung function. Prospective randomized trials comparing CyberKnife with wedge resection are necessary to confirm equivalence.

Highlights

Standard therapy for operable stage I non-small cell lung cancer (NSCLC) is lobectomy (Ginsberg and Rubinstein, 1995)
Sublobar resection with adequate margins (1–2 cm) or adjuvant brachytherapy has been advocated for high-risk surgical patients with small peripheral lesions (Narsule et al, 2011)
High-risk was defined as a postbronchodilator percent predicted forced expiratory volume in 1 s (FEV1) of less than 50%, a carbon monoxide diffusing capacity (DLCO) of less than 50%, age greater than 75, or severe comorbid medical conditions

Summary

Introduction

Standard therapy for operable stage I non-small cell lung cancer (NSCLC) is lobectomy (Ginsberg and Rubinstein, 1995). Sublobar resection (segmentectomy or wedge resection) with adequate margins (1–2 cm) or adjuvant brachytherapy has been advocated for high-risk surgical patients with small peripheral lesions (Narsule et al, 2011). Such treatment in appropriately selected patients provides acceptable locoregional control without the early mortality and potentially clinically meaningful decline in lung function associated with lobectomy (Lee et al, 2003; Santos et al, 2003)

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