SESSION TITLE: Lung Cancer
SESSION TYPE: Original Investigation Slide
PRESENTED ON: Tuesday, October 28, 2014 at 02:45 PM - 04:15 PM
PURPOSE: To report the cumulative incidence of RIRF following SBRT with fiducial tracking for inoperable peripheral stage I NSCLC.
METHODS: Inoperable patients diagnosed from August 2005 to August 2011 with biopsy-proven stage I NSCLC (AJCC 7th edition) were evaluated and followed for a minimum of 30 months. Gross tumor volumes (GTVs) were contoured using lung windows; the margins were expanded by 5 mm to establish the planning treatment volume (PTV). Doses delivered to the PTV ranged from 45 to 60 Gy in 3 or 5 fractions (BED Gy10 >100 Gy). Treatments were delivered utilizing SBRT with fiducial tracking. Clinical examination and PET/CT were completed at 6-month follow-up intervals. CT detected rib fractures were recorded and dated. Cumulative incidence of rib fracture was estimated via the Kaplan-Meier method.
RESULTS: Forty patients median age 76 (12 men and 28 women) were evaluated. The median maximum tumor diameter was 2.7 cm (range, 1.4-5.0 cm). A median dose of 50 Gy was delivered over a 3 to 13 day period (median, 7 days). At a median potential follow-up of 53 months, 3 year Kaplan-Meier locoregional control and overall survival estimates were 95% and 72%. Radiation induced rib fractures were identified in 9 patients. The estimated cumulative incidence of RIRF was 26.5% at 3 years. The median time to the onset of rib fracture was 24 months (range, 7-31 months).
CONCLUSIONS: RIRF are often detected following peripheral stage I NSCLC SBRT with fiducial tracking. Novel treatment strategies are necessary to limit RIRF incidence.
CLINICAL IMPLICATIONS: SBRT with fiducial tracking is an effective treatment option for medically inoperable patients with stage I NSCLC. RIRF is an expected complication of this treatment approach which requires timely diagnosis and management.
DISCLOSURE: The following authors have nothing to disclose: Shaan Kataria, Furhawn Shah, Nima Aghdam, Leonard Chen, Simeng Suy, Sean Collins, Ryan Malik, Cristina Reichner, Eric Anderson, Brian Collins
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