ESTRO 2024 - Abstract Book

S1634

Clinical - Lung

ESTRO 2024

911

Digital Poster

Local Ablative Therapy Combined with Pembrolizumab in Oligometastatic Non-Small Cell Lung Cancer

Hye In Lee 1 , Eun Kyung Choi 1 , Su Ssan Kim 1 , Young Seob Shin 1 , Junhee Park 1 , Chang-Min Choi 2 , Shinkyo Yoon 2 , Hyeong Ryul Kim 3 , Si Yeol Song 1 1 Asan Medical Center, Department of Radiation Oncology, Seoul, Korea, Republic of. 2 Asan Medical Center, Department of Oncology, Seoul, Korea, Republic of. 3 Asan Medical Center, Department of Thoracic and Cardiovascular Surgery, Seoul, Korea, Republic of

Purpose/Objective:

This study aimed to evaluate the efficacy of local ablative therapy (LAT) in combination with pembrolizumab in patients with synchronous oligometastatic non-small cell lung cancer (NSCLC) and to identify patient subsets who would benefit from LAT.

Material/Methods:

In this single-center retrospective study, we identified patients diagnosed with synchronous oligometastatic NSCLC (≤5 metastatic lesions with ≤3 organs involved), without EGFR or ALK mutations, and treated with first -line pembrolizumab between January 2017 and December 2022. Patients who underwent LAT, including surgery or radiotherapy at all disease sites, were compared with those who did not receive LAT. Progression-free survival (PFS) and overall survival (OS) were calculated from the start date of treatment. A recursive partitioning analysis (RPA) model was developed using prognostic factors for PFS.

Results:

Of the 258 patients included, 78 received LAT and 180 received systemic therapy alone. The median follow-up duration was 15.5 months (IQR 9.3 – 24.3). In the entire cohort, LAT was independently associated with significantly improved PFS (HR, 0.64; 95% CI, 0.45 – 0.92; P=0.015) and OS (HR, 0.61; 95% CI, 0.40 – 0.93; P=0.020). In the propensity score-matched cohort (n=74 in each group), the median PFS was 19.9 months (95% CI, 14.6 – 32.9) for the LAT group and 9.6 months (95% CI, 7.5 – 18.1) for the non-LAT group (P=0.003). The median OS was 42.2 months (95% CI, 24.6 – 70.7) and 20.5 months (95% CI, 13.4 – 47.5) for the LAT and non-LAT groups, respectively (P=0.045). The RPA model, including the number of metastatic lesions, ECOG performance status, and PD-L1 expression, classified patients into three risk groups with distinct PFS (P<0.001). LAT improved PFS in the low- (P=0.038) and intermediate-risk groups (P=0.043), while no significant difference was observed in the high-risk group (P=0.721). In the LAT group, consolidative LAT after systemic therapy showed a trend toward improved PFS compared to upfront LAT (P=0.052).

Conclusion: