ESTRO 2024 - Abstract Book

S2158

Clinical - Upper GI

ESTRO 2024

Belgium. 4 Ghent University Hospita, Radiation Oncology, Gent, Belgium. 5 Institut Jules Borde, Radiation Oncology, Brussels, Belgium. 6 EpiCURA Baudour,, Radiation Oncology, Baudour, Belgium. 7 Limburgs Oncologisch Centrum, Radiation Oncology, Hasselt, Belgium. 8 CHU UCL Namur, Radiation Oncology, Namen, Belgium. 9 Hôpital de Jolimont, Radiation Oncology, Jolimont, Belgium. 10 OLV Aalst, Radiation Oncology, Aalst, Belgium. 11 Clinique Saint-Jean, Radiation Oncology, Brussels, Belgium. 12 UZ Brussel, VUB, Radiation Oncology, Brussels, Belgium. 13 UZ-KULeuven, Radiation Oncology, Leuven, Belgium. 14 Cliniques universitaires Saint-Luc, Radiation Oncology, Woluwe-Saint Lambert, Belgium. 15 AZ Groeninge, Radiation Oncology, Kortrijk, Belgium. 16 Iridium Netwerk, Radiation Oncology, Wilrijk, Belgium. 17 University of Antwerp, Centre for Oncological Research (CORE)-IPPON, Faculty of Medicine and Health Sciences, Wilrijk, Belgium

Purpose/Objective:

Stereotactic body radiotherapy (SBRT) is frequently applied for both primary liver tumours and liver metastases. Within a multicentre national project, we investigated patterns of care for liver SBRT and factors influencing local control (LC) and overall survival (OS).

Material/Methods:

Patients with liver lesions treated with SBRT were prospectively registered within the convention of innovative radiotherapy techniques, a collaboration between the Belgian Cancer Registry, the national College of Radiotherapy, the National Institute for Health and Disability Insurance (NIHDI) and Belgian radiotherapy centres. In addition to patient and tumour factors, technical data on application of markers, personalised immobilisation, image guidance and radiotherapy techniques were collected. Survival data were retrieved by linkage with the Belgian Crossroads Bank for Social Security. Radiotherapy centres were contacted for individual patient data on primary tumour histology, LC, follow-up imaging, prior liver-directed therapies, GTV and PTV volumes and doses. Non-coded data were collected and stored at the Belgian Cancer Registry. All data were coded for further analyses. LC and OS were calculated using the Kaplan-Meier method. LC was analysed for each treated lesion while OS was calculated for every patient. Univariable and multivariable analysis of prognostic factors were performed using Cox proportional hazard models. Results were stratified according to various patient, tumour and treatment related factors.

Results:

From August 2013 to December 2019, fourteen centres treated 353 patients with SBRT for a total of 409 liver lesions. SBRT was applied for 66 primary liver lesions and 343 liver metastases. Colorectal adenocarcinoma was the most common primary tumour histology (n=170, 42%). Median age at the start of SBRT was 70 years (range 22-93). Median time between diagnosis of the primary tumour and the start of liver SBRT was 29 months (range 0.8-362). Patient, tumour and treatment characteristics are summarised in Table 1.

A gradual uptake in liver SBRT and a higher dose prescription were observed over time (Fig. 1).

After a median follow-up of 23.6 months, 1year- and 2year-OS probabilities were 74% and 50% respectively. In univariable analysis, a superior OS was found for patients with a better performance status (PS) at diagnosis (PS 2+ vs. PS 0; HR 2.26, p=0.002), prior liver surgery (p=0.044), image fusion for target delineation (p=0.032), higher BED10 and smaller PTV volume. After multivariable analysis, a higher OS was observed for patients with better PS (PS 2+ vs.