BACKGROUND: The abscopal effect suggests that the impact of radiotherapy extends beyond the direct tumor local regression, due to activation of the immune response. Its effectiveness may vary depending on whether high- or low-radiation doses are used. In FLASH therapy, the high-dose rate treatment induces systemic effects that may trigger an abscopal response. METHODS: We discuss a phenomenological, computational model, based on available in vivo FLASH radiotherapy data, to quantitatively analyze the possible synergistic effects with the immune system to produce a systemic effect. RESULTS: The method enables a quantitative assessment of the interaction between FLASH radiotherapy and the activated immune response, based on observations of metastatic shrinkage due to the FLASH treatment of the primary tumor.

• Keywords
• FLASH radio-therapy immunotherapy, Gompertz law, abscopal effect, mathematical modeling, radiotherapy,
• Publication type
• Journal Article MeSH

Objectives: The quantitative analysis of tumor progression-monitored during and immediately after therapeutic interventions-can yield valuable insights into both long-term disease dynamics and treatment efficacy. Methods: We used a computational approach designed to support clinical decision-making, with a focus on personalized patient care, based on modeling therapy effects using effective parameters of the Gompertz law. Results: The method is applied to data from in vivo models undergoing neoadjuvant chemoradiotherapy, as well as conventional and FLASH radiation treatments. Conclusions: This user-friendly, phenomenological model captures distinct phases of treatment response and identifies a critical dose threshold distinguishing complete response from partial response or tumor regrowth. These findings lay the groundwork for real-time quantitative monitoring of disease progression during therapy and contribute to a more tailored and predictive clinical strategy.

• Keywords
• monitoring treatment response, predictive personalized tumor progression, support clinical decision-making, tumor growth,
• Publication type
• Journal Article MeSH