ASTRO: Many lung cancers stand little chance against stereotactic body radiation therapy—and conventional radiotherapy’s days are numbered too

BOSTON—Stereotactic body radiation therapy (SBRC) has beaten the pants off conventional radiation therapy in the Veterans Health Administration, significantly boosting both overall and lung cancer-specific survival in thousands of patients with stage I non-small cell lung cancer (NSCLC) in the first decade of the 21st century.

By the end of that timeframe, the conventional approach had all but been banished by its higher-performing offspring, which uses advanced imaging to deliver targeted radiation to tumor cells while sparing surrounding tissue.

The analysis behind the findings was presented Sept. 26 at the annual meeting of the American Society for Radiation Oncology (ASTRO).

Lead author Matthew Boyer, MD, PhD, a resident in radiation oncology at Duke University, said there were about 77,000 lung cancer cases within the VA from 2001 to 2010. About 14,000 were stage I non small-cell lung cancer and about 3,000 of those patients had radiation.

Of these, around 1,200 patients had conventionally fractionated radiation therapy and 468 had SBRT.

From 2001 to 2010, Boyer said, four-year overall survival increased by an absolute value of about 16 percent, reflecting more than a doubling of overall survival (12.7 percent of patients diagnosed in 2001 vs. 28.5 percent in 2010).

And four-year lung cancer-specific survival increased by an absolute value of about 17 percent (33.9 percent of patients diagnosed in 2001 vs. 50.4 percent in 2010).

“We noticed that this was uniquely related to an increase in SBRT, and the rates of SBRT went up dramatically over this time,” Boyer said while displaying a slide showing a jump in SBRT utilization from 39.7 percent in 2001 to 60.3 percent in 2010.

By the latter year, the majority of patients were having SBRT rather than conventional RT—which plummeted from 95.1 percent in 2001 to 4.9 percent in 2010.

So “indeed there is improved survival following SBRT,” Boyer said. “In our two groups, looking at either conventional fractionated RT or SBRT, those who received SBRT had almost a doubling of their four-year overall survival, with a hazard ratio of 0.6, or a 40 percent decrease in the risk of death.”

Boyer noted that a multivariate analysis considering other factors showed that, unsurprisingly, increasing age correlated with increasing risk of death, as did comorbidities and higher-stage cancer.

However, “interestingly enough, the treatment era was no longer significant,” he said. “Although we saw improvement in survival, when we take into consideration the use of SBRT, what was really significant was the adoption of SBRT during the 2001-2010 timeframe.”

Surprising but not unexpected  

During a Q&A period, an attendee asked Boyer if he and his co-authors were surprised by the magnitude of the improvement in survival.

Very much so, Boyer replied. “Prospective studies that have looked at SBRT have kind of suggested that, but we were surprised,” he said.

What’s not surprising, given the results, is that no U.S. veteran with stage I lung cancer is being treated with conventional, fractionated radiation therapy in 2016.

“All these patients are getting stereotactic radiation,” Boyer said. “It is the standard across the VA health system.”

Another attendee wondered if SBRT is becoming the standard outside the VA.

The question was taken up by Andrew Farach, MD, of Houston Methodist Hospital, who had preceded Boyer with a presentation showing that widespread adoption of SBRT improved survival rates for thousands of elderly patients diagnosed with early stage lung cancer from 2004 to 2012.

“I think virtually every resident coming out these days not only is trained in SBRT but expects to be able to deliver SBRT to their patients as they enter practice,” Farach said. “It’s in widespread utilization now, and we were equally surprised [as Boyer and colleagues] by the significant improvement that we saw.

“I was excited to see Dr. Boyer’s data as well, because it’s pretty rare in medicine,” Farach added. “You know, we read a lot of papers, and it’s rare to see this dramatic an improvement over such a short period of time.”