Stereotactic radiotherapy (SBRT) as a sole or salvage therapy in non-small cell lung cancer patients.

The aim of this study is to present evaluation of treatment toxicity and the rate of local control in non-small cell lung cancer patients (NSCLC) treated with stereotactic body radiotherapy (SBRT). The analysis was performed on heterogenous group of 61 NSCLC patients, treated with SBRT between 2005 and 2008. It included 26 patients in clinical stage I, 5 in stage II, 22 in III and 8 in stage IV. In 30 patients SBRT was the only treatment, in 20 patients SBRT was a salvage therapy and in 11 patients SBRT was used as a boost after conventionally fractionated radiotherapy (CRT). The mean age was 67 yrs. Fifteen patients received chemotherapy in the course of treatment. Radiation doses were converted into Linear Quadratic Equivalent Dose at 2Gy per fraction (LQED2). The survival curves were plotted using Kaplan-Maier estimator and analyzed using log-rank test and Cox method. The LQED2 doses administered in stereotactic technique ranged from 8 Gy to 150 Gy and the fraction doses from 5 Gy to 24 Gy. The rate of 2 years local control correlated with LQED2: it was 81% in a group of patients who received over 110 Gy, compared to 51% and 33% in a group of patients who received 60-110 Gy and less than 30 Gy respectively. Prior radiotherapy and advanced clinical stage correlated with lower doses at SBRT and hence lower rate of local control. The tolerance of SBRT was satisfactory: there was no RTOG grade 3 - 4 toxicity. The results are consistent with findings of other authors and indicate that LQED2 doses delivered by SBRT in the treatment of NSCLC should be higher than 110 Gy whenever clinically feasible. SBRT used as a salvage therapy was less effective, because use of high doses was precluded due to consideration of normal tissue tolerance.