PFS Benefit Occurs with Complete vs Incomplete Consolidative RT in ES-SCLC

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

Ninia described the parameters of the trial, explaining that it was a retrospective analysis of 70 patients with ES-SCLC. He then briefly outlined the efficacy results of the study, indicating that significant progression-free survival (PFS) and overall survival (OS) benefits were observed with complete vs incomplete consolidation radiotherapy. When stratified by disease burden, however, only the PFS benefit remained significant in the complete consolidation arm, as the OS benefit was insignificant.

The study initially included 84 patients with ES-SCLC but excluded 5 due to incomplete records and 9 who did not receive consolidative radiotherapy.

At a median follow-up of 38.2 months, complete consolidative radiotherapy produced a significant improvement for OS (HR, 0.49, 95% CI, 0.28-0.86, P = .012) and PFS (HR, 0.49, 95% CI, 0.29-0.81, P = .005) vs incomplete consolidative therapy. Additionally, 1- and 2-year OS rates were 89.3% and 48.4% in the complete group and 52.5% and 19.7% in the incomplete group, respectively.

When stratified by disease burden for patients with oligometastatic SCLC, PFS significantly improved in the complete consolidation arm (HR, 0.29; 95% CI, 0.12-0.69, P = .005), but not OS (HR, 0.81; 95% CI, 0.34-1.98; P = .65).

Transcript:

We retrospectively looked at a group of patients treated at our institution in New Haven, Connecticut from 2013 to 2020. We identified, in the end, 70 patients for whom we had enough records to include in our analysis. Among those 70 patients, 28 of them [received] complete consolidation, whereas the other 42 [received] incomplete consolidation. Of those 70, as well, 36 of them [had] oligometastatic [disease]. Of 36 patients [with] oligometastatic [disease], 24 underwent complete consolidation [therapy].

Not surprisingly, we found that patients who with oligometastatic [disease] were more likely to undergo complete consolidation than those who with polymetastatic [disease], probably, in part, because giving radiation treatments to all those sites of disease is easier when there are less of them to target. Let me get to the punchline in 2 parts here.

When we looked at all of our patients [with SCLC] who [received] complete consolidation, we found that [receiving] complete consolidation was associated with a better PFS [and] better OS. One-year OS rate was 89.3% in patients who [received] complete consolidation vs 52.5% in those [who received] incomplete. At 2 years, it was 48.4% vs 19.7%, and the p-value for that was significant, it was 0.012.

We stratified by disease burden based on that relationship that we noted between whether patients got complete consolidation and their actual burden of disease. When we only looked at those who got who were oligometastatic and whether they got complete consolidation, we found that the PFS benefit remained. Those patients still did have a statistically significant PFS benefit.

[A benefit of] 41.7% vs 0% at 1 year with a p-value of .005 [was shown]. Unfortunately, these patients did not have an OS benefit that was statistically significant compared [with] those receiving incomplete consolidation when we only looked at patients who [had] oligometastatic [disease].

Reference

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