1351P - Efficacy of early stereotactic body radiotherapy to the primary lung lesion in patients with NSCLC harboring sensitive EGFR mutations treated with first-line EGFR-TKIs

Background

The addition of consolidative stereotactic body radiotherapy (SBRT) improved the survival for EGFR-mutated NSCLC treated with EGFR-TKIs. However, the optimal timing of SBRT remains unclear. The current study aimed to investigate the clinical outcome of the early and delayed SBRT to primary lung lesions in patients with EGFR-mutated NSCLC treated with first-line EGFR-TKIs.

Methods

The patients with EGFR-mutated advanced (stage IIIB-IV) NSCLC who were suitable to receive SBRT for the primary lung tumors after first-line EGFR-TKIs treatment were enrolled. The early SBRT group was defined as patients who received SBRT for their primary lung lesions at the maximal response of TKIs treatment. The delayed SBRT group was defined as patients who received SBRT after the occurrence of oligoprogression in the primary lung tumor. The primary endpoints were progression-free survival 1 (PFS1, time from the start of first-line EGFR-TKIs treatment to disease progression) and PFS2 (time from the start of first-line EGFR-TKIs treatment to disease progression after SBRT). Overall survival (OS) and adverse effects (AEs) were secondary endpoints. A two-sided P value of 0.05 was considered statistically significant.

Results

One hundred and eighty-four patients were screened, and 34 patients were eligible for enrollment in this study. The median age of the entire cohort was 61 years (range, 37–67 years), and 22 (64.7%) patients were male. Eighteen patients (52.9%) were non-smokers. Of the 34 eligible patients, 19(55.9%) received early SBRT to lung primary tumor and 15(44.1%) received delayed SBRT to lung primary tumor. The early SBRT group had a significantly longer median PFS1 than the delayed SBRT group (30.0 months vs. 9.0 months, P＜0.001). The median PFS2 in the early SBRT and delayed SBRT groups were 42.0 and 33.0 months, respectively (P = 0.521). The median OS of both groups has not been reached. No severe toxicities (≥grade 3) were recorded.

Conclusions

Early SBRT to the primary lung lesion significantly improved PFS and is a new potentially effective and tolerable treatment option for patients with advanced NSCLC who had stable disease during first-line EGFR-TKIs treatment.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.