ESTRO 2025 - Abstract Book

S1515

Clinical – Mixed sites & palliation

ESTRO 2025

Conclusion: Combining chemoradiotherapy, eventually followed by a boost dose on the prostate, yields an excellent local control in patients with synchronous prostate and rectal cancer. Rectal dose escalation should be carefully considered as it may result in substantial late morbidity.

Keywords: synchronous prostate and rectal cancer

References: Lavan N, Kavanagh D, Martin J, et al. The curative management of synchronous rectal and prostate cancer. Br J Radiol 2016; 89: 20150292.

2219

Digital Poster SBRT in bone metastases disease: local control and pain flare in patients treated with single-fraction versus multi-fraction schemes María C. Matienzo Barreto, Lidia Gómez Perea, José Javier Martín Ortega, María Elena García Morales, Claudio Fuentes Sánchez Radiation oncology, Hospital Universitario Nuestra Señora de la Candelaria, Santa Cruz de Tenerife, Spain Purpose/Objective: Bone metastases are exceedingly frequent among patients with advanced cancer disease, especially in those with breast, prostate or lung carcinomas. Stereotactic body radiotherapy (SBRT) has demonstrated benefit for local control (LC) in oligometastatic and oligorrecurrent patients. Pain flare, defined as a “temporary worsening of bone pain in the treated metastatic area”, is a potential acute side effect of radiotherapy. The aim of this study is to evaluate LC of bone metastases and incidence of pain flare in patients treated with different SBRT schemes. Material/Methods: Retrospective observational study from August 2016 to November 2023. Patients with oligometastatic and oligorrecurrent disease treated with SBRT in the Radiation Oncology Department of a level 3 hospital were included in the study. Results: A total of 128 SBRT in 86 patients were administered in bone metastatic lesions. Median follow-up was 27 months (range 16.1 – 34.1). 62 lesions (48.44%) had their origin in a primary prostate tumour, 46 (35.94%) in breast tumours and the rest in gynaecological, digestive and lung tumours. Median age was 56 years old (range 45 – 65), 59.38% male, 40.62% female. Regarding bony treatment sites, SBRT was delivered to the pelvis in 37 cases (28.91%), ribs in 22 (17.19%), lumbar spine in 21 (16.41%), dorsal spine in 19 (14.84%), sacrum in 11 (8.59%), femur in 8 (6.25%), cervical spine in 5 (3.91%), scapula in 2 (1.56%), humerus in 2 (1.56%) and sternum in 1 (0.78%). 33 locations (25.78%) were treated with a single-fraction (SF) scheme and 95 locations (74.22%) with multi-fraction (MF) scheme. The most used fractions were 2x12Gy in 57 locations (47.66%), 3x9Gy in 31 locations (24.22%), 1x18Gy in 27 locations (21.09%), 1x24Gy in 4 locations (3.13%) and 3x10Gy in 4 locations (3.13%). LC of bone metastatic disease treated with SBRT was achieved in 78.78% of patients treated with SF scheme and 87.37% of patients treated with MF scheme (p=0.23). Only 4 patients (3.12 %) presented pain flare, of which 2 were in the single-fraction group and 2 were in the multi-fraction group (SF 6.06% versus MF 2.11%, p=0.25). Conclusion: In our experience, both SF and MF SBRT can be considered a safe and effective treatment for LC of bone metastatic lesions. No statistically significant differences were found in local control or side effects comparing both groups.