Stereotactic body radiation therapy for early-stage non-small-cell lung cancer utilizing a helical intensity modulated image-guided approach.

e17524 Background: To report the techniques and results of a large cohort of patients treated with stereotactic body radiotherapy (SBRT) for early-stage non-small-cell lung cancer (NSCLC) using image-guided helical intensity modulated radiation therapy (IMRT) and FDG-PET assisted targeting. Methods: Between February 2005 and August 2010, 79 patients with stage 1 NSCLC were treated with SBRT. 59 patients had T1 tumors and 20 patients had T2 tumors. 62 patients had biopsy proven malignancies and 17 patients were treated empirically based on strong clinical indications. Central tumor location did not disqualify patients. All patients underwent FDG-PET or FDG-PET/CT scanning in the treatment position for planned fusion with a separate kilovoltage (KV) CT simulation. Rigid immobilization was achieved during CT simulation using a double vacuum cast device with abdominal compression. SBRT was delivered via 12 Gy x 4 or 12 Gy x 5 fractionation scheme (48-60 Gy total). Megavoltage CT images were obtained on the treatment unit prior to therapy and repeated mid-fraction with comparison to the KV CT simulation planning images to assure set-up accuracy. Serial follow-up with FDG-PET or FDG-PET/CT studies were performed at 3 months and every 6 months thereafter on all surviving patients. Results: Median patient age was 73 years. Mean tumor size was 2.3 cm (range 0.5 – 6 cm). Median follow-up was 24 months (range 4-78 months). Overall local control rate (LCR) was 94% (95% confidence interval (CI), 86-97%) based on serial FDG-PET. LCR for T1 tumors was 95% vs. 90% for T2 tumors (p = 0.60). Entire cohort overall survival rate (OSR) was 87% (CI, 78-93%) at 1 year and 58% (CI, 47-68%) at 3 years. T1 patients had a 3-year OSR of 71% vs. 43% OSR for T2 patients (p = 0.04). No patients developed life threatening radiation pneumonitis or pulmonary complications. Chest wall pain or rib fracture was reported in 8 patients (10%; CI, 5-19%). Conclusions: Image-guided SBRT with helical IMRT delivered in 4 or 5 fractions of 12 Gy with rigid immobilization and FDG-PET assisted targeting is an effective treatment for early NSCLC and is associated with excellent local control rates and acceptable treatment-related morbidity.