ESTRO 2025 - Abstract Book

S1147

Clinical – Lower GI

ESTRO 2025

222

Digital Poster Feasibility and Tolerance of Deep Hyperthermia Combined with Radiochemotherapy in Locally Advanced Rectal Cancer: First Spanish Experience Laura Ferrera-Alayón, Bárbara Salas Salas, Antonio Alayón Afonso, Miguel Sánchez Carrascal, Laura López Molina, Rafael Alexis Santana Hernández, Marta Llorez Sáez-Bravo Radiation Oncology, Hospital Universitario de Gran Canaria Dr Negrin, Las Palmas de Gran Canaria, Spain Purpose/Objective: To evaluate the feasibility, tolerability, and safety of integrating hyperthermia with conventional neoadjuvant treatment in patients with locally advanced rectal cancer (LARC). Material/Methods: From January 2020 to August 2023, patients with locally advanced rectal cancer (LARC) were considered for hyperthermia treatment in combination with standard neoadjuvant therapy and were enrolled in this prospective study (EudraCT 2020-335-1). Exclusion criteria included metal prosthesis in the treatment area, pacemaker, massive effusions (pleural or ascites), open wounds, abscesses, burns, hemorrhages, sensory disturbances, pregnancy, and patient refusal. Patients were treated with either short course radiotherapy (SCRT) of 5 Gy in 5 fractions or long course radiotherapy (LCRT) of 2 Gy in 25 fractions, following different chemotherapy regimens as per the tumor board's protocol. Hyperthermia was administered twice weekly for 60 minutes during radiotherapy (RT) using the ALBA 4D deep hyperthermia device. Tolerance and toxicity were evaluated using the integrated CTCAE 4.03/QMHT criteria, with an additional assessment of tolerance reported via the UMC scale Results: Of the 123 patients considered, 67 met the inclusion criteria and were enrolled in the study: 34 (50.7%) in the short course radiotherapy (SCRT) group and 33 (49.3%) in the long-course radiotherapy (LCRT) group. A total of 243 hyperthermia sessions were conducted during radiotherapy (RT): 65 sessions for SCRT and 178 sessions for LCRT. All 34 patients (100%) in the SCRT group completed more than 50% of the prescribed sessions, whereas 21 out of 33 patients (63.64%) in the LCRT group achieved this adherence. The median and mean temperatures achieved during SCRT were 40.33°C and 40.37°C, respectively (range 38.72-41.45°C). For LCRT, the median and mean temperatures were 40.44°C and 40.21°C, respectively (range 38.56-41.66°C). Details of the temperature data are shown in Table 1. Tolerance to the treatment varied among patients, as detailed in Table 2. Hyperthermia treatment was interrupted in 23 patients (34%) due to several reasons: pain in the treatment area (47.8%), radiotherapy toxicity (21.7%), technical issues (17.4%), pressure in the treatment area (8.7%), and claustrophobia (4.3%). Only 14 patients (20.9%) experienced grade 3 gastrointestinal toxicity from radiochemotherapy. The main symptoms among these patients included hemorrhoids, rectal obstruction, and diarrhea. All patients completed the prescribed course of radiotherapy without interruptions and underwent surgery within the scheduled timeframe.