Stereotactic body radiotherapy (SBRT) was found to be safe and effective for stage I non-small cell lung cancer (NSCLC), according to a multi-institutional analysis of patterns-of-care and patterns-of-outcome. Additionally, radiotherapy dosage was identified as a major treatment factor influencing local tumor control and overall survival.
SBRT is considered the treatment of choice for early-stage NSCLC if patients are inoperable because of additional medical conditions. This is based on several prospective phase II trials, which reported consistently high rates of local tumor control. However, these studies only included small numbers of patients, the methodology of SBRT varied between the studies, and SBRT was mainly practiced in specialized centers. Therefore, safety and efficacy of SBRT practiced in routine clinical practice outside of study protocols was not well analyzed.
A working group called Extracranial Stereotactic Radiotherapy was formed within the German Society for Radiation Oncology, and this group performed a patterns-of-care and patterns-of-outcome analysis looking at safety and efficacy of SBRT for stage I NSCLC in Germany and Austria. In their publication in the Journal of Thoracic Oncology (2013; doi:10.1097/JTO.0b013e318293dc45), the researchers reported that they examined data from 582 patients treated at 13 institutions between 1998 and 2011. The average follow-up for all patients was 21.4 months and the maximum was 144 months (12 years). Follow-up exceeded 3 years for 108 patients. The 3-year freedom from local progression was 79.6% for all 582 patients.
The biological effective dosage was the most significant factor influencing the freedom from local progression and overall survival. The researchers did not observe evidence of a learning curve or improvement of results with larger SBRT experience and implementation of new radiotherapy techniques.
The research team concluded that SBRT for stage I NSCLC was safe and effective in this multi-institutional, academic environment, despite considerable inter-institutional variability and time trends in SBRT practice.