S976
Clinical - Oligometastatic cancer
ESTRO 2026
July 2025. Data were obtained from the prospective international multicenter MOMENTUM study (1), a registry-based study. Eligible patients had nodal recurrence following prior curative treatment for prostate cancer. Descriptive statistics were used to analyze treatment patterns, inter-center variation, and data completeness. Results: We included 414 patients from 12 centers across seven countries. The cohort was homogeneous across centers with respect to age and performance status. Baseline performance status was missing in 34 %, but when reported, 99 % had good performance status. Although all patients received local ablative radiotherapy, treatment intent was reported inconsistently across centers: 26.3 % were classified as curative, 67.6 % as palliative, and 6.0 % were not reported. A total of 460 targets were treated. Most patients (88 %) had a single target irradiated, while 9 % received treatment to multiple targets. Dose– fractionation schedules varied substantially between centers. While 35 Gy/5 fractions was the most frequently used regimen, some centers favored alternatives such as 30 Gy/3 fractions, 45 Gy/3 fractions, or 50 Gy/5 fractions. Most treated targets were infradiaphragmatic lymph nodes, with few in supradiaphragmatic or other locations. This pattern was consistent across centers. At six months, local control was available in 151 patients, with only two documented local failures. Reporting was not available in 263 patients (64 %), limiting interpretation.
Conclusion: This analysis of data from the international
MOMENTUM registry provides valuable insight into patient selection for MR Linac–based radiotherapy in oligorecurrent prostate cancer. Patient characteristics were largely comparable across centers, while variation in dose and fractionation schedules reflects the diversity of current clinical practice. This diversity provides an opportunity to explore how different treatment approaches affect outcomes. Continued updates and refinement of the registry will further strengthen its ability to support evidence-based optimization of MR-guided radiotherapy. References: de Mol van Otterloo SR, Christodouleas JP, Blezer ELA, Akhiat H, Brown K, Choudhury A, et al. The MOMENTUM Study: An International Registry for the Evidence-Based Introduction of MR-Guided Adaptive Therapy. Front Oncol. 2020;10:1328. Keywords: Prostate cancer, oligometastatic disease Digital Poster 2917 Modeling overall survival in patients with oligometastatic non–small cell lung cancer based on longitudinal cancer dynamics Maksym Fritsak 1 , Hubert S. Gabry ś 1 , Sebastian M. Christ 1 , Martin Huellner 2 , Matthias Guckenberger 1 , Stephanie Tanadini-Lang 1 1 Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland. 2 Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland Purpose/Objective: Oligometastatic disease (OMD) represents an intermediate stage between localized and widespread cancer, where limited metastases diagnosed on imaging at one timepoint may enable curative-intent treatment. In non–small cell lung cancer (NSCLC), the prognostic stratification remains challenging, with the cancer dynamics beeing not considered. This study
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