High-Dose Hypofractionated Stereotactic Body Radiation Therapy (sbrt) in the Treatment of Patients with Primary Non-Small Cell Lung Cancer (Nsclc)

To evaluate the treatment outcomes and toxicities in patients with NSCLC treated with SBRT. From July 2004 to March 2007, 27 primary NSCLC tumors were treated with high-dose, hypofractionated SBRT. All patients were immobilized with a body cast inside a stereotactic body frame and underwent either 4DCT (n = 22) or breath-hold/gated CT simulation (n = 5). The attached Table reveals the characteristics of the patients treated. Patients were medically inoperable, and the median age was 72 years (range 43–86). Mean pulmonary function test values were: FEV1 1.63L, FEV1/FVC 59%, and DLCO/VA 67% of the predicted value. Patients had an ITV created by combining the GTVs from the 4DCT or breath-hold/gated CT. The PTV was then generated via a uniform 5 mm margin around the ITV. The mean PTV was 49.1 cm3 (range 5.1–120.3). Treatment planning was performed using either dynamic conformal arcs (n = 17) or static beams (n = 10). The mean maximum dose in the PTV was 56.7 Gy (range 16.9–76.7). The mean V20 was 4.9% (range 0–10.0). The typical dose prescription was 3 fractions of 18 Gy over 5–8 elapsed days (total dose 54 Gy). Local control (LC) was determined by chest CT and/or 18FDG-PET/CT obtained after SBRT. One patient was lost to follow-up. Median follow-up in the remaining 26 patients was 9.0 months (range 0.7–32.7). Considering all patients treated, actuarial 1- and 2-year LC rates were 92.3 and 76.9%, respectively. Overall survival (OS) was 84.6% at 1 year and 75.2% at 2 years. One- and 2-year local progression-free survival (LPFS) were 78.1 and 57.9%, respectively. In the 16 stage IA patients, 1- and 2-year LPFS were 88.9 and 66.7%, which corresponded to both a 1- and 2-year OS of 88.9%. No stage IA patient developed local-only disease progression. There was 1 case of grade 5 radiation pneumonitis occurring 5 months after SBRT. No other patient experienced greater than grade 1 pulmonary toxicity, and there was no correlation between dosimetric parameters and toxicity. SBRT is highly effective and well-tolerated as a definitive treatment technique for medically inoperable stage I NSCLC, and is similarly efficacious as aggressive local treatment for primary tumors in stage IV patients. Our experience using 54 Gy in 3 fractions in an elderly population with medical co-morbidities has resulted in outcomes superior to conventional RT and a 2-year OS comparable to surgery. The value in escalation of dose beyond 54 Gy has yet to be established, and is the subject of ongoing study in the cooperative group setting.Tabled 1Patient characteristicsClinical StageNumber of patientsMean PTV (cm3)Median prescribed dose (Gy)IA1646.154IB661.449.5IIIA17.245IV (primary tumor treated)453.454 Open table in a new tab