Abstract 7364: Candidate identification for SBRT versus surgery in early-stage NSCLC with interlobar pleural involvement: A multicenter retrospective study

Abstract Purpose: This study aimed to compare survival outcomes between surgery and stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (ES-NSCLC) with interlobar pleural involvement (ILPI), and to further identify patients who benefit more from SBRT. Methods: This retrospective study analyzed 573 ES-NSCLC patients with ILPI, treated with surgery (n=379) or SBRT (n=194) across four centers. Propensity score matching (PSM) was employed to minimize confounding factors between treatment groups. Survival outcomes, including cancer-specific survival (CSS), disease-free survival (DFS) were estimated using the Kaplan-Meier method and compared with the log-rank test. Subgroup analyses utilized Cox proportional hazards models. We also conducted a comparative analysis of treatment-related adverse events (TRAEs) and assessed health-related quality of life (HRQoL) using the EORTC QLQ-C30. Results: In the entire cohort, 3-year CSS was comparable between surgery and SBRT (HR, 1.48, 95% CI, 1.0-2.3; P = 0.075). In the PSM-matched cohort, CSS and DFS showed no significant differences (CSS: HR, 1.02, 95% CI, 0.6-1.5; P = 0.822; DFS: HR, 1.38; 95% CI, 0.8-2.5; P = 0.374). Multivariate Cox analysis identified several independent prognostic factors for CSS, including IPI features (site: HR, 0.48, 95% CI, 0.3-0.8; P = 0.009; location: HR, 2.05, 95% CI, 1.2−3.6; P = 0.014; type: HR, 8.00, 95% CI, 1.8−35.1; P = 0.006) and patient characteristics (age: HR, 1.88, 95% CI, 1.1−3.3; P =0.027; smoking history: HR, 2.28 95% CI, 1.4−3.7; P = 0.001). Crucially, in the subgroup of patients over 70 years of age, SBRT was associated with significantly superior CSS compared to surgery (HR, 0.37, 95% CI, 0.2-0.8; P = 0.007). Specifically, CSS was improved in SBRT patients over 70 years with ILPI characterized by: Abutment-type ILPI (HR, 0.36, 95% CI, 0.1-1.0; P = 0.045), left lung oblique fissure (OF) involvement (HR, 0.21, 95% CI, 0.1-0.7; P = 0.011), or central ILPI location (HR, 0.10, 95% CI, 0.0-0.6; P = 0.012). Conversely, surgery showed better DFS in patients < 70 years and those with peripheral ILPI or right OF involvement. Regarding TRAEs, surgery was predominantly associated with pain (28.5%), while the SBRT cohort experienced fatigue (22.7%). The HRQoL showed SBRT was associated with significantly better preservation of emotional function and avoided the worsening of pain observed after surgery, which showed greater improvements in role and social function. Conclusions: SBRT offers survival outcomes comparable to surgery for ES-NSCLC with ILPI without increasing the burden of TRAEs or compromising HRQoL. Patient age and ILPI characteristics are critical factors in guiding treatment selection. SBRT is particularly beneficial for patients over 70 years, especially those presenting with abutment-type ILPI, left OF involvement, or central ILPI. Citation Format: Zhengkun Cai, Zhiyong Yuan, Yue Wang. Candidate identification for SBRT versus surgery in early-stage NSCLC with interlobar pleural involvement: A multicenter retrospective study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7364.