ESTRO 2024 - Abstract Book

S1706

Clinical - Lung

ESTRO 2024

1990

Digital Poster

Safety of judicious stereotactic ablative radiotherapy for central and ultra-central lung tumors

Marco Galaverni, Federico Colombo, Cristina Dell'Anna, Elisabetta Lattanzi, Claudia Grondelli, Francesco Salaroli, Ilaria Renna, Stella Gianni, Giovanni Ceccon, Maria Luisa Bergamini, Nunziata D'Abbiero, Nicola Simoni

Azienda Ospedaliero-Universitaria di Parma, Radiation Oncology Unit, Parma, Italy

Purpose/Objective:

Stereotactic ablative radiotherapy (SABR) represents an effective option for patients with early-stage non-small cell lung cancer and lung metastasis. However, SABR for tumors within 2 cm of the proximal bronchial tree (PBT) has been associated with increased rates of not neglectable adverse events. Aim of the present study was to analyze clinical efficacy of SABR in treating central and ultra-central lesions, in terms of disease control and bronchial toxicity.

Material/Methods:

Central and ultra-central tumors treated at our Institution with SABR were retrospectively analyzed. Tumor centrality was defined according to the definition of the International Association for the Study of Lung Cancer (IASLC) (1). Ultra-central lesions were defined as those with planning target volume (PTV) directly abutting PBT. According to Tekatli et al. tumors were further sub-divided based on lesion distance to PBT (2). Tumors located <1 cm from the trachea/main bronchi were defined as group A; tumors with a distance of >1 cm from the trachea/main bronchi, but within 1 cm from the intermediate/lobar bronchi were included in Group B; lesions with a distance of ≥ 1 cm from PBT, but ≤ 2 cm from mediastinum were defined as Group C (2). Local control (LC), progression free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method. Incidence and grade of clinical and radiological bronchial toxicity were evaluated. Statistical analysis was performed to assess the impact of clinical and treatment-related variables on outcome and toxicity occurrence.

Results:

Between 2018-2022, 57 patients accounting for 60 lung lesions, including 13 (21.7%) ultra-central and 47 (78.3%) central tumors, received SABR (Table 1). Thirty-two (53.3%) patients were treated for early-stage lung cancer and 28 (46.7%) for lung metastases. Median internal gross tumor volume (iGTV) and planning target volume (PTV) were 7.7 (IQR 4.6-17.8) and 33.1 (IQR 18.5-52.2) cc, respectively. The prescribed SABR dose ranged from 35 Gy to 70 Gy over 5 to 15 fractions, with a median biological effective dose (BED10) of 96 Gy (IQR 72-105 Gy) and 72 Gy (IQR 70.3-97 Gy) to the iGTV and PTV, respectively.