Kate O'Rourke

September 27, 2016

BOSTON — The increasing use of stereotactic body radiation therapy (SBRT) rather than conventional radiation in patients with early-stage non–small cell lung cancer (NSCLC) has doubled survival rates, according to an analysis of data from the Veterans Health Administration (VA).

"The increased use of SBRT is strongly associated with improved survival," said lead author of the study Matthew Boyer, MD, PhD, a resident at Duke University Medical Center in Durham, North Carolina.

Dr Boyer and colleagues reviewed data on more than 1600 VA lung cancer patients who were treated with radiation from 2001 to 2010. The median length of follow-up was 4 years.

For patients who received SBRT rather than conventional radiotherapy, there was a doubling in both overall survival (18.8% vs 37.7%; hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.54 - 0.68) and lung cancer–specific survival (28.3% vs 53.2%; HR, 0.48; 95% CI, 0.38 - 0.60).

"Overall survival and cancer-specific survival are significantly improved with SBRT compared to conventional fractionation," said Dr Boyer.

He spoke at a press conference during the American Society for Radiation Oncology (ASTRO) 2016 Annual Meeting, where the study was presented.

SBRT is a treatment that both improves outcomes and offers a higher value, said Brian Kavanagh, MD, MPH, president-elect of ASTRO and a radiation oncologist at the University of Colorado, Denver, who moderated the press conference.

"Although we are talking about a treatment that is of an advanced technology that has only been allowed in the last 10 years or so, it is also a smarter, more efficient, and more cost-effective way to do things," said Dr Kavanagh. "It involves fewer trips to the treatment center for the patient, fewer side effects, and is generally a lot easier to take."

SBRT is a tumor-ablative radiation modality that accurately and precisely damages a tumor with a high dose while sparing normal tissue. Surgical resection and stereotactic SBRT in early-stage lung cancer represent potentially curative treatments.

"Lung cancer patients are living relatively longer with SBRT relative to conventional radiotherapy," said Dr Kavanaugh. "It would be tragic if we couldn't give this treatment to the patients who need it."

Other research indicates that overall survival following SBRT is roughly 48 months, which is significantly greater than historical overall survival of roughly 24 months with conventionally fractionated radiation therapy (JAMA. 2010;303:1070-1076; J Thorac Oncol. 2006;1:112-9).

The new study directly compared the two approaches.

Dr Boyer and colleagues analyzed data from the VA Central Cancer Registry (VACCR) and the Corporate Data Warehouse for patients who were diagnosed with stage I NSCLC in the opening decade of the new millennium. The VACCR includes data on all cancer diagnoses within the VA and accounts for 3% of all cancer diagnoses in the United States. SBRT was identified by CPT (current procedural terminology) codes and documentation of dose or fraction number. Conventional radiation therapy was 20 fractions or more.

Of the 3012 stage I NSCLC patients identified, 1203 received conventionally fractionated radiation, and 468 received SBRT. The mean age of the patients was 72 years, 89.4% had a smoking history, 98.6% were male, 50.5% had stage IA cancer, and 41.5% had squamous cell histology.

During this period, the researchers noted that the improved survival was associated with increased SBRT utilization. In 2001, when the study period started, 95% of patients who received radiation had conventional radiation therapy, and the remainder received SBRT. By 2010, 60% of patients who underwent radiation therapy were receiving SBRT.

The survival advantage persisted (HR, 0.72; 95% CI, 0.61 - 0.84; P<.001). A multivariate analysis took into account factors such as age, use of positron emission tomography (PET), no use of PET, treatment era (2001 - 2005 vs 2006 - 2010), squamous cell histology vs no squamous cell histology, stage IA vs IB, and number of comorbidities.

The researchers found that older age (HR, 1.01 per year; P = .022), higher Carlson Comorbidity Index score (HR, 1.52 for a score of 2 vs 0; P < .001), and higher stage (HR, 1.39 for stage IB vs IA; P < .001) were associated with improved survival.

Notably, there was no significant difference in survival with respect to receipt of PET scans for staging or treatment era. According to Dr Boyer, this indicates that the improvement in survival for patients receiving radiation was strongly correlated with increased utilization of SBRT and not with improved staging with PET scans or other improvements in treatment and care during the study period.

Studies have shown that SBRT is underutilized in blacks, but results from the Accountability for Cancer Care through Undergoing Racism and Equity trial (ACCURE), which was also presented at the ASTRO meeting, show that interventions can improve the rates of SBRT usage in blacks (abstract 77).

Dr Boyer noted that lung cancer causes more than one million deaths each year worldwide and that an increasing number of patients are being diagnosed with stage I lung cancer, owing to the aging of the population and advanced screening techniques.

Dr Boyer and Dr Kavanagh have disclosed no relevant financial relationships.

American Society for Radiation Oncology (ASTRO) 2016 Annual Meeting. Abstract 18. Presented September 25, 2016.

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