ESTRO 2025 - Abstract Book

S1322

Clinical - Lung

ESTRO 2025

1475

Digital Poster Prognostic Impact of Tumor Solid Components in Stereotactic Body Radiotherapy for Clinical Stage Tis– 1N0M0 Lung Cancer Junki Fukuda 1 , Hiroshi Doi 1 , Saori Tatsuno 1 , Takaya Inagaki 2 , Naoko Ishida 1 , Takuya Uehara 1 , Masahiro Inada 1 , Kiyoshi Nakamatsu 1 , Makoto Hosono 1 , Atsushi Kono 3 , Kazunari Ishii 3 , Yukinori Matsuo 1 1 Department of Radiation Oncology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan. 2 Department of Radiology, Wakayama Medical University, Wakayama, Japan. 3 Department of Radiology, Kindai University Faculty of Medicine, Osaka-Sayama, Japan Purpose/Objective: Consolidation tumour ratio (CTR) is a recognised prognostic factor in early-stage lung cancer. However, evidence regarding the prognostic significance of CTR in stereotactic body radiotherapy (SBRT) remains limited. In this study, we retrospectively analysed patients with early-stage lung cancer treated with SBRT to assess the impact of tumour size and CTR on treatment outcomes. Material/Methods: The analysis included 65 patients with 67 lesions of clinical stage 0–IA lung cancer treated with SBRT at our institution between 2008 and 2021. Clinical staging was defined according to the UICC 8th ed. The median age was 76 years (range, 60–88 years). The tumour stages were as follows: Tis: 3, T1mi: 2, T1a: 11, T1b: 29, and T1c: 22 tumours. Twelve patients had squamous cell carcinoma (Sq) and 53 patients had non-Sq. The prescribed dose was 48 Gy (range, 42–52 Gy) in 4 fractions. Patients with a follow-up period < 6 months without any events were excluded. Local control (LC), progression-free survival (PFS), disease-specific survival (DSS), and overall survival (OS) were evaluated using the Kaplan-Meier method. The Cox proportional-hazards model was used to assess factors potentially associated with outcomes.

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