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Stereotactic body radiation therapy use increases, yields improved early-stage NSCLC survival
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The increased use of stereotactic body radiation therapy doubled 4-year survival rates in veterans with stage I non–small cell lung cancer, according to a Veteran’s Health Administration analysis presented at the ASTRO Annual Meeting.
“Lung cancer causes more than 1 million deaths each year worldwide,” Matthew Boyer, MD, PhD, radiation oncologist at Duke University, said in a press release. “Moreover, an increasing number of localized, or stage I, lung cancer diagnoses are occurring due to an aging population and advanced screening techniques.”
Stereotactic body radiation therapy was developed to advance imaging techniques to deliver highly targeted radiation to a tumor to limit damage to the surrounding tissue. As this modality preserves healthy tissue, its adoption has increased since its induction in the 1990s.
However, the optimal radiation modality to treat early-stage NSCLC is still unknown.
Therefore, Boyer and colleagues used data from the Veteran’s Affairs Central Cancer registry and the VA Corporate Data Warehouse to compare survival outcomes and causes of death in patients with early-stage NSCLC who received stereotactic body radiation therapy or conventional radiotherapy.
Of the 14,177 patients (mean age, 72; 98.6% male) identified with stage I NSCLC, 3,012 received radiation as their only treatment — including 1,203 patients who received conventional fractionation and 468 patients who received stereotactic body radiation therapy.
Overall, 89.4% of patients were current or former smokers at the time of diagnosis, 50.5% of patients were diagnosed with stage IA NSCLC and 41.5% were diagnosed with squamous cell carcinoma.
From 2001 to 2010, 4-year OS in patients who underwent any type of radiation rose from 12.7% to 28.5%, and lung cancer-specific survival increased from 33.9% to 50.4%. This increase correlated greater stereotactic body radiation therapy use, from 4.7% to 60.3%.
“It is very rare for a study to show that double the number of patients were likely to be alive at 4 years due to the introduction of a new treatment,” Boyer said in the release. “We identified that this doubling was due to the introduction of these advanced radiation techniques collectively termed stereotactic body radiation therapy.”
At 4-year follow-up, patients who received stereotactic body radiation therapy demonstrated superior OS (37% vs. 18.8%; HR = 0.6; 95% CI, 0.54-0.68) and lung cancer–specific survival (53.2% vs. 28.3%; HR = 0.48; 95% CI, 0.38-0.6) compared with those who received conventional radiotherapy.
Multivariate analysis showed stereotactic body radiation therapy conferred nearly a 30% reduction in the risk for death compared with conventional radiotherapy (HR = 0.72; 95% CI, 0.61-0.84).
Researchers found that receipt of PET scans for staging and treatment era did not significantly change the results of the multivariable analysis, which again suggested the use of stereotactic body radiation therapy lead to the increases in survival.
“These findings of improved survival in stage I lung cancer patients in general, and those undergoing radiation specifically, are generalizable to patients outside the Veterans Health Association,” Boyer said in the release. “Although a number of studies are underway to define the best treatment for stage I NSCLC, our study, and others, indicate that advances in radiation treatment and delivery can improve patient survival and that stereotactic body radiation therapy should be the standard treatment for patients treated with radiation for stage I NSCLC.” – by Kristie L. Kahl
Reference:
Boyer MJ, et al. Abstract 18. Presented at: ASTRO Annual Meeting; Sept. 26-28, 2016; Boston.
Disclosure: HemOnc Today could not confirm the researchers’ relevant financial disclosures at the time of reporting.
Perspective
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Henning Willers, MD
Stereotactic body radiation therapy (SBRT), or stereotactic ablative radiotherapy, is a high-precision radiation technique that pinpoints high “ablative” radiation doses at the tumor while sparing surrounding normal organs in typically one to five treatments. SBRT has become widely adopted for the treatment of patients with medical inoperable early-stage non–small cell lung cancer over the past 10 years, despite the lack of large randomized phase 3 trials comparing SBRT with conventionally fractionated radiation therapy (CRT), which spreads the radiation dose over a course of approximately 30 to 35 treatments in 6 to 7 weeks.
Accordingly, there have been very sparse data suggesting that the use of SBRT has actually improved OS of these patients compared with the historically used CRT, which generally was associated with 5-year OS rates of around 20% and local tumor control rates of only approximately 50%. In the absence of large randomized trial data, analyses of large patient cohorts in national databases provide attractive alternate sources to gather useful information on the outcomes of SBRT.
To this end, the Veteran’s Administration study on more than 2,000 patients, presented by Boyer and colleagues, demonstrates superior 4-year OS for SBRT compared with CRT (30% vs. 19%). The observed OS for SBRT is lower than recent long-term outcomes of SBRT would suggest — where 5-year OS exceeds 40%. This discrepancy may well be due to the specific nature of the Veteran’s Administration NSCLC population with regard to medical comorbidities and smoking history.
References:
Koshy M, et al. Radiother Oncol. 2015;doi:10.1016/j.radonc.2014.12.004.
Nyman J, et al. Radiother Oncol. 2016;doi:10.1016/j.radonc.2016.08.015.
Sibley GS. Cancer. 1998;82:433-438.
Zheng X, et al. Int J Radiat Oncol Biol Phys. 2014;doi:10.1016/j.ijrobp.2014.05.055.
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