ESTRO 2025 - Abstract Book

S1854

Clinical – Upper GI

ESTRO 2025

4059

Digital Poster Exploring Acute Toxicity and Potential Implications of Stereotactic Body Radiation Therapy for Liver Lesions: A Single Institution Experience Nikolay Tolev 1 , Manuela Vartanyan 2 , Rositza Krasteva 3 , Zahari Zahariev 1 1 Radiation oncology, Uni Hospital Oncology Center, Panagyurishte, Bulgaria. 2 Radiation oncology, Oncology Hospital “D-r Marko A. Markov”-Varna, Varna, Bulgaria. 3 Medical oncology, Uni Hospital Oncology Center, Panagyurishte, Bulgaria Purpose/Objective: Reporting unexpected "immediate" acute radiation toxicity in patients of Uni Hospital Oncology Center Bulgaria treated with SBRT for unresectable liver metastases or primary malignancies [1]. Toxicity was manifested by generalized tremor and subsequent subfebrile temperature shortly after first SBRT fraction delivery. Material/Methods: Between 01 April 2017 and 11 November 2024 a total of 309 patients underwent SBRT for liver lesions in our radiation therapy department. Five of them (2 men and 3 women) developed an “immediate” acute adverse effect. Median age was 62 years (range 55-65), with median ECOG PFS 0 (range 0-1). Two patients were treated for primary liver carcinoma, the other three received SBRT for liver metastases from colorectal carcinoma. Pathology report confirmed colorectal adenocarcinoma histology in three of the cases, hepatocellular carcinoma in one case and cholangiocarcinoma – in one case. Patients with 1 to 9 lesions with a median tumor volume of 66.18 cm 3 (range 11.8 – 133.9 cm 3 ) underwent SBRT with a total dose of 35-45 Gy delivered in 3 to 5 fractions. In one patient, the liver SBRT volume-dose constraints were not approached [2]. Treatment characteristics are summarized in table 1. All patients have received prior systemic treatment and none of them has undergone previous surgical interventions or has had a history of liver cirrhosis. Normal full blood count, liver panel blood chemistry, creatinine, apTT and INR were registered at treatment initiation in all patients.

Results: Five patients experienced an acute adverse effect shortly after application of first SBRT fraction, which did not occur anymore until the end of treatment. Patients had Grade 2 tremor (CTCAE version 5), which developed on average within the 31 st minute (range 16-45 minutes) after treatment, and lasted on average of 34 minutes (range 18-60 minutes) after administration of first fraction of radiation therapy with a subsequent subfebrile temperature. This episode was followed by a decrease in body temperature associated with an abundant sweating. Due to the above adverse reaction, corticosteroids and COX 2 inhibitor were administered to four of the patients, and benzodiazepine was administered to two of them. One of the patients did not receive any symptomatic treatment, but nevertheless the presenting symptoms subsided gradually within an hour.