Expanded Use of SABR

Dr Chang and colleagues have also examined the effect of SABR on patients with operable NSCLC.


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A 2015 pooled analysis compared the OS associated with SABR with that of lobectomy and mediastinal lymph node dissection/sampling in 58 patients with stage I, operable NSCLC.2 SABR significantly increased OS at 3 years compared with lobectomy.

“The results of this study surprised many people including myself,” Dr Chang said. “The study has several limitations, including the small patient number, but it highlights the important issue to the oncology community that patients with early-stage, operable lung cancer need to have a multidisciplinary team so that patients can hear about the different treatment modalities and the possible limitations of each.”

Patients with more advanced bulky disease are typically ineligible for SABR, according to Dr Chang.

“When disease is bulky that chance to have distant failure is much higher, so local treatment by itself is not as effective as with early-stage lung cancer,” he said. “For locally advanced lung cancer SABR does not play a key role in management.”

Yet for stage IV lung cancer, treatment concepts are changing, Dr Chang noted.

“Previously, people thought about systemic treatment only for these patients and radiation therapy was underused,” Dr Chang said. “Now, palliative radiation therapy at low doses for symptom control or pain control is beginning to play a role.”

SABR may be used to improve PFS, or potentially OS, among patients who have a good response to chemotherapy, targeted therapy, or immunotherapy.

Future Uses

Some research on SABR may identify which patients can benefit the most from local treatments at such a high dose. Studies may, for example, investigate whether adding immunotherapy to SABR can benefit particular patients.

One such study already recruiting is the I-SABR study, which will look at SABR with or without immunotherapy in patients with stage I, stage IIa, or isolated parenchymal recurrent NSCLC.3

“For the past decade technology advanced and provided us with the opportunity to deliver radiation therapy at such a high dose with minimal side effects,” Dr Chang said.

“In the past 5 years, research has advanced the biology of immunotherapy and now, in the next decade, combining technology and biology will be a real research opportunity.”

References

  1. Sun B, Brooks ED, Komako RU, et al. 7-year follow-up after stereotactic ablative radiotherapy for patients with stage I non-small cell lung cancer: results of a phase 2 clinical trial. Cancer. 2017 Mar 27. doi: 10.1002/cncr.30693 [Epub ahead of print]
  2. Chang JY, Senan S, Paul MA, et al. Stereotactic ablative radiotherapy versus lobectomy for operable stage I non-small-cell lung cancer: a pooled analysis of two randomised trials. Lancet Oncol. 2015;16(6):630-7. doi: 10.1016/S1470-2045(15)70168-3.
  3. ClinicalTrials.gov. Clinical trials comparing immunotherapy plus stereotactic ablative radiotherapy (I-SABR) versus SABR alone for stage I, selected stage IIa or isolated lung parenchymal recurrent non-small cell lung cancer: I-SABR. NCT03110978. https://clinicaltrials.gov/ct2/show/study/NCT03110978. Accessed July 17, 2017.