Main Session

Sep 29

PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care

3252 - A Prospective Observational Trial of Single Fraction Stereotactic Ablative Body Radiotherapy for Oligometastatic Patients (SONIC-O): Preliminary Results

03:45pm - 05:00pm ET

Poster Hall - Exhibit Hall A

Screen: 30

POSTER

Presenter(s)

Federico Colombo, MD - Azienda Ospedaliero Universitaria Parma, Parma, Emilia-Rom

F. Colombo¹, M. Galaverni Sr¹, M. Bergamini¹, G. Ceccon¹, C. dell'Anna¹, S. Gianni¹, E. Lattanzi¹, I. Renna¹, F. Salaroli¹, C. Grondelli², A. Alfano¹, C. Ghetti¹, M. Tiseo¹, L. Ruffini¹, N. Sverzellati¹, N. D'Abbiero¹, and N. Simoni¹; ¹AOU Parma, Parma, Italy, ²Aou parma, Parma, Italy

Purpose/Objective(s):

To report preliminary data from a prospective observational clinical study (SONIC-O) assessing the use of single-fraction stereotactic ablative body radiotherapy (SF-SAbR) in oligometastatic patients (OMPs).

Materials/Methods:

Oligometastatic patients, according to ESTRO-EORTC criteria, treated at our Institution with SF-SAbR between 2023 and 2024 were analyzed. Eligible patients had oligometastatic disease (1 to 5 lesions) from miscellaneous solid-organ malignancies. Exclusion criteria were central pulmonary lesions, metastases located < 5 mm from spinal cord and/or any hollow gastro-intestinal structure, and/or > 5 cm in largest diameter. Prior or concurrent multi-fraction SAbR was not an exclusion criterion. Primary endpoints were local control (LC) and treatment-related adverse events (CTCAE). Secondary objectives included progression-free survival (PFS), overall survival (OS), and next systemic therapy-free survival (NSTFS).

Results:

In total, 80 OMPs accounting for 131 lesions received SF-SAbR. The most common target sites were lungs (32.8%), nodes (32.8%) and bones (28.2%). The most common primary malignancies were prostate (43.8%), lung (18.8%) and kidney (17.5%). At the time of enrollment, 47 (61.0%) patients had received =1 line of systemic therapy (median 1, range 1-5). SF-SAbR was delivered with Linac-based Volumetric Modulated Arc Radiotherapy (VMAT) using a Simultaneous Integrated Boost (SIB) approach. Median prescribed dose to Planning Target Volume (PTV) and Gross Tumor Volume (GTV) was 28 Gy and 32 Gy for lung metastases, 16 Gy and 20 Gy for node, and 16 Gy and 20 Gy for bone lesions, respectively. The median number of treated metastases for SF-SAbR course was 1 (range 1-4). Three (3.8%) patients received a second SF-SAbR course at disease recurrence. With a median estimated follow-up of 19.4 months (95% CI 17.9-21.1), the overall LC rate was 97.7%, with a 1-year freedom from local progression (LPFS) of 97.5% (95% CI 94.7-100). Grade =1 SF-SAbR-related side effects occurred in 13 (16.3%) patients, with a single G3 case (pneumonitis). No G4-5 adverse events were observed. Tumor recurrence occurred in 32 (40.0%) patients, with a distant and mixed (local + distant) pattern as first site of failure in 29 (90.6%) and 3 (9.4%) cases, respectively. All 3 local failures occurred in lung metastases from colorectal adenocarcinoma. One- and 2-year PFS rates were 68.8% (95% CI 59.3-79.7) and 55.3% (95% CI 43.3-70.5), and the corresponding OS rates 93.8% (95% CI 88.6-99.2) and 84.5% (95% CI 75.6-94.5), respectively. One- and 2-year NSTFS rates were 80.0% (95% CI 71.7-89.3) and 68.8% (95% CI 58.3-81.6), respectively.

Conclusion:

SF-SAbR in OMPs provides excellent tumor control and tolerability. Furthermore, SF-SAbR optimally integrates with systemic therapies, allowing prolonged duration of their efficacy for selected patients.