Assessing Consolidative Radiation in Extensive-Stage Small Cell Lung Cancer

CancerNetwork® spoke with James Ninia, MD, a third-year resident of radiation oncology at the Yale School of Medicine, about the rationale behind evaluating complete vs incomplete consolidative radiotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC) in a study he presented at the 2024 American Society of Radiation Oncology (ASTRO) Annual Meeting.¹

Ninia described the treatment landscape for patients with limited metastatic burden, whose survival has benefitted with metastasis-directed radiotherapy. He referenced the phase 2 SABR-COMET trial (NCT01446744), in which an 8-year overall survival (OS) benefit and 5-year PFS benefit was seen with stereotactic ablative radiation therapy vs palliative standard of care (SOC).² He stated that in SABR-COMET and similar trials, patients with ES-SCLC were not included.

He further explained that this patient population received consolidated radiotherapy to residual intrathoracic disease following first-line chemotherapy in the CREST trial (NTR1527).³ He explained that the trial occurred prior to an approval for immunotherapy in SCLC, with the major finding being a 2-year OS benefit associated with radiation to residual disease.

Ninia indicated that there was a more pronounced benefit for patients with oligometastatic SCLC undergoing consolidated chest radiation after first-line chemotherapy compared with those with polymetastatic disease. He concluded by stating that his study aimed to assess whether offering additional radiotherapy outside of the thorax would influence outcomes for patients with polymetastatic disease.

Transcript:

For patients with limited metastatic burden, metastasis-directed radiotherapy has previously been shown to be associated with improved survival for certain types of cancer in multiple clinical trials, including [the phase 2 SABR-COMET trial] and a few others. However, patients with metastatic SCLC, what we would call extensive-stage SCLC, were not included in these prior trials.

Moreover, patients with extensive-stage SCLC are also routinely offered consolidated radiotherapy to any residual intrathoracic disease that they might have after first-line chemotherapy. This is based on a trial called the CREST trial. This was done before immunotherapy was approved for SCLC, and that trial showed that patients who got radiation to residual intrathoracic disease after chemotherapy were more likely to be alive 2 years later than patients who did not.

Based on this, prior work in our department had shown that some patients with SCLC who have this limited disease burden that we termed oligometastatic SCLC do better after getting consolidated chest radiation after first-line chemotherapy than those with significant disease burden, which we termed polymetastatic. Our thought was to see whether offering radiotherapy to any additional sites of residual disease outside of the thorax might be playing a role in some of these findings or not.

References

1. Ninia JG, Verma N, Laird JH, et al. Complete vs. incomplete consolidative radiotherapy in patients with extensive-stage small cell lung cancer. Presented at the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting; September 29 – October 2, 2024; Washington, DC. Poster 2109
2. Harrow S, Palma DA, Olson R, et al. Stereotactic radiation for the comprehensive treatment of oligometastases (SABR-COMET): extended long-term outcomes. Int. J. Radiat. Oncol. 2022;114(4):611-616. doi:10.1016/j.ijrobp.2022.05.004
3. Slotman BJ, Tinteren HV, Praag JO, et al. Use of thoracic radiotherapy for extensive stage small-cell lung cancer: a phase 3 randomised controlled trial. Lancet. 2015;385(9962):36-42. doi:10.1016/S0140-6736(14)61085-0