SBRT Improves Overall and Disease-Specific Survival in Stage I NSCLC
Continued adoption of stereotactic body radiation therapy (SBRT) to treat early stage non-small cell lung cancer (NSCLC) improved overall survival (OS) and lung cancer–specific survival (LCSS), according to a study presented at the 2016 annual meeting of the American Society for Radiation Oncology.1,2
An aging population and advanced screening techniques are resulting in an increase in diagnoses of stage I lung cancer, explained Matthew Boyer, MD, PhD, a resident in radiation oncology at Duke University, Durham, North Carolina, and lead author of the study. Although most patients with stage I NSCLC undergo surgery, radiation therapy is recommended when surgery cannot be tolerated or nonsurgical management is preferred.
SBRT delivers a highly targeted radiation dose and limits damage to surrounding tissues, an important consideration in patients with NSCLC because these tumors are near or in vital organs including the heart or lungs.
In this study, researchers sought to determine if the use of SBRT improved outcomes for patients with NSCLC. They identified 3012 patients with stage I NSCLC diagnosed from 2001 to 2010 who underwent radiation therapy as a primary treatment from more than 14,000 records of patients who met these criteria, using the Veterans Affairs Central Cancer Registry (VACCR). Of the 3012 patients, 468 underwent SBRT and 1203 received conventional radiation therapy (CRT).
Study participants were an average age of 72 years, 98.6% were male, and 89.4% were current or former smokers at diagnosis; 50.5% had stage IA NSCLC and 41.5% had squamous cell carcinoma.
At 4 years follow-up, overall survival was significantly higher in the patients who underwent SBRT vs those who received CRT (37.0% vs 18.8%, respectively; (hazard ratio [HR] 0.60; P <.001). Improved overall survival was largely attributed to an increase in LCSS during the 4 years of follow-up: 53.2% for SBRT vs 28.3% for CRT (HR, 0.39; P <.001).
Multivariate analysis demonstrated risk of death was nearly 30% less for patients treated with SBRT vs CRT. Other factors associated with improved survival included older age, higher Charlson comorbidity score, and higher disease stage.
Of note, use of PET scans for staging or treatment era did not produce a significance difference in survival, leading the researchers to conclude that the improved survival rates were strongly correlated with increased use of SBRT to treat stage I NSCLC and not with improved staging with PET scans or other improvements in treatment and care over the same time period.
1. Advances in radiation therapy have improved survival rates for early stage lung cancer patients [news release]. Boston, MA: Astro; September 25, 2016. https://mail.google.com/mail/b/475/u/0/#inbox/157626d5b3bd9d0f. Accessed September 26, 2016.
2. Boyer MJ, Williams C, Kelley MJ, Salama JK. Survival with stereotactic body radiation therapy (SBRT) and conventional radiation therapy (CRT) in stage I non-small cell lung cancer patients in the Veterans Affairs system. Int J Radiat Oncol Biol Phys. 2016. [Epub ahead of print]