Abstract
BackgroundStereotactic body radiation therapy (SBRT) for stage I non-small cell lung cancer (NSCLC) is considered standard of care in the medically inoperable patient population. Multiple methods of SBRT delivery exist including fiducial-based tumor tracking, which allows for smaller treatment margins and avoidance of patient immobilization devices. We explore the long-term clinical outcomes of this novel fiducial-based SBRT method.MethodsIn this single institutional retrospective review, we detail the outcomes of medically inoperable pathologically confirmed stage I NSCLC. Patients were treated with the Cyberknife SBRT system using a planning target volume (PTV) defined as a 5-mm expansion from gross tumor volume (GTV) without creation of an internal target volume (ITV). Dose was delivered in three or five equal fractions of 10 to 20 Gy. Pretreatment and posttreatment pulmonary function test (PFT) changes and evidence of late radiological rib fractures were analyzed for the majority of patients. Actuarial local control, locoregional control, distant control, and overall survival were calculated using the Kaplan-Meier method.ResultsSixty-one patients with a median age of 75 years were available for analysis. The majority (80 %) of patients were deemed to be medically inoperable due to underlying pulmonary dysfunction. Eleven patients (18 %) developed symptomatic pneumothoraces secondary to fiducial placement under CT guidance, which precipitously dropped to 0 % following transition to bronchoscopic fiducial placement. The 2-year rib fracture risk was 21.4 % with a median time to rib fracture of 2.9 years. PFTs averaged over all patients and parameters demonstrated small absolute declines, 5.7 % averaged PFT decline, at approximately 1 year of follow-up, but only the diffusing capacity of lung for carbon monoxide (DLCO) demonstrated a statistically significant decline (10.29 vs. 9.01 mL/min/mmHg, p = 0.01). Five-year local control, locoregional control, and overall survival were 87.6, 71.8, and 39.3 %, respectively.ConclusionsDespite reduced treatment margins and lack of patient immobilization, SBRT with fiducial-based tumor tracking achieves clinically comparable long-term outcomes to other linac-based SBRT approaches.
Highlights
The 2016 incidence of newly diagnosed lung cancer is estimated to be 224,390 with approximately 158,080 of these patients succumbing to their disease [1]
Patients were treated with the Cyberknife Stereotactic body radiation therapy (SBRT) system using a planning target volume (PTV) defined as a 5-mm expansion from gross tumor volume (GTV) without creation of an internal target volume (ITV)
We investigate clinical outcomes of patients with stage I non-small cell lung cancer (NSCLC) from a single institution treated with robotically delivered fiducial-based SBRT
Summary
The 2016 incidence of newly diagnosed lung cancer is estimated to be 224,390 with approximately 158,080 of these patients succumbing to their disease [1]. The results demonstrated low-dose CT screening yielded a 20 % relative reduction in mortality from lung cancer and a 6.7 % relative reduction in all-cause mortality [6] These practice changing results prompted the US Preventive Services Task Force in 2013 to recommend annual screening for lung cancer with low-dose CT scans in patients aged 55 to 80 with a 30 pack-year smoking history who are current smokers or quit within the past 15 years [7]. As implementation of these new screening guidelines becomes ubiquitous, an increase in the incidence of early-stage NSCLC is plausible. We explore the long-term clinical outcomes of this novel fiducial-based SBRT method
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