ESTRO 2024 - Abstract Book

S2250

Clinical - Upper GI

ESTRO 2024

1 Medical Center - University of Freiburg, Faculty of Medicine, Department of Radiation Oncology, Freiburg, Germany. 2 German Cancer Research Center, German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany. 3 Albert-Ludwig University Freiburg, Berta-Ottenstein-Programme, Freiburg, Germany. 4 Medical University of Graz, Department of Radiation Oncology, Graz, Austria

Purpose/Objective:

The use of stereotactic radiotherapy (SBRT) in the upper abdomen is challenging due to the proximity of organs at risk (OAR) to the target volume (PTV). In this analysis we evaluated toxicity and local control after upper abdominal SBRT.

Material/Methods:

We defined two risk groups depending on the overlap of the PTV with an OAR. Patients in group A presented an overlap between the PTV and OARs (high toxicity profile). To protect the OARs, a sub-volume (Simultaneous Integrated Protection, SIP) was defined from the overlapping areas of the PTV and the PRV-OAR (planning organ at risk volume: OAR + 4mm isotropic expansion). This sub-volume was treated with lower radiation doses in order to comply with the dose guidelines for the respective OAR. Patients in group B (low toxicity profile) were treated without SIP.

Results:

Between April 2007 and February 2018, a total of 279 SBRTs were performed in 195 patients: 25 on the pancreas, 14 on the adrenal gland, 82 on liver metastases and 141 on primary liver tumours. 78 target volumes were treated with SIP (group A) and 201 without SIP (group B). We registered a total of 36 local recurrences (12.9%), of which 12 were in group A and 24 in group B. The rate of grade 3 toxicity was 2.15%. Of a total of 6 grade 3 toxicities, we registered 3 haemorrhages from the common hepatic artery or the gastric antrum (1.1%), 2 hyperbilirubinaemias (0.7%) and 1 cholangiosepsis (0.3%). No grade 4 toxicity occurred. The rate of grade 1-2 toxicity was 40.5%. In group A (treatment with SIP), the rate of grade 3 toxicities was 0.7% (n=2) and in group B (treatment without SIP), the rate of grade 3 toxicities was 1.4% (n=4). 143 patients did not experience any toxicity.

Conclusion:

Performing SBRT with Simultaneous Integrated Protection resulted in good local control with comparable rates of grade 3 toxicities despite the significant overlap of PTV with OARs.

Keywords: SBRT, simultaneous integrated protection, SIP

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Poster Discussion