PAMPLONA, Spain. Scientists at the University of Navarra have developed a first-of-its-kind method to quantify how much radiation blood absorbs during cancer treatment accurately. This breakthrough could lead to more personalised, preventive, and safer radiotherapy.
The research, led by Dr. Marina García-Cardosa of the University of Navarra’s Medical Physics and Biophysics group ( PhysMed ) and recognised by international institutions, addresses a long-standing gap: while radiotherapy traditionally seeks to protect nearby organs, blood — a moving, vital tissue circulating throughout the body — has largely been ignored in dose calculations.
Dr. García-Cardosa’s doctoral thesis proposes an innovative shift: treating blood as an “organ at risk” and adjusting therapy to shield it when possible. “Each blood cell that passes through a radiation field receives a small amount of energy,” she explained. “Even though the dose per cell may be low, the cumulative effect across treatments can weaken the immune system or cause hematologic toxicity.”
The study was carried out in collaboration with physicians and researchers from the University of Navarra Cancer Center, which enabled validation of this innovation in a real clinical setting.
The new method, called FLIP-HEDOS, integrates patient-specific anatomical information, blood circulation patterns data, and radiotherapy plans to simulate precisely when and how much blood is irradiated. By combining medical physics, biophysics, oncology, and engineering, it allows clinicians to calculate personalised scenarios and predict cumulative exposure across treatment cycles.
Findings show that factors such as a tumour’s proximity to major blood vessels, the type of radiation applied, and the variability of each patient's cardiac output (the amount of blood the heart pumps per minute) significantly shape blood irradiation — and, by extension, the immune response. “The immune system is highly sensitive to radiation. Even very low doses can impair critical cells, such as lymphocytes, the white blood cells responsible for coordinating the body's defence. If a significant number of these cells are damaged, the body's ability to respond to infections, inflammation or even the tumour itself can be compromised,” Dr. García-Cardosa said. “This becomes especially relevant in patients receiving both radiotherapy and immunotherapy.”
This work was honored among the best oral communications at the European Society for Radiotherapy and Oncology (ESTRO) in Austria (May 2025) and also been distinguished in specialised congresses such as the Radiation Research Society Conference in the United States (September 2024) and by the Spanish Society of Medical Physics at the national level (May 2025). In addition, portions of their results have been published in high-impact scientific journals, including Radiation Physics and Chemistry , Physics in Medicine & Biology , and Clinical Cancer Research .
Regarding its potential in oncological treatments, the FLIP-HEDOS framework could help simulate the distribution of drugs or radiopharmaceuticals, as well as evaluate new strategies for radioprotection and haematological toxicity. “Thinking of blood as a dynamic organ to be protected represents a paradigm shift in modern radiotherapy. This research not only responds to a scientific need, but also a clinical imperative: to offer safer treatments without compromising oncological efficacy", emphasises Professor Javier Burguete, Professor of Medical Physics and Biophysics at the University of Navarra and director of the thesis. The research has also benefited from the advice of Professor Harald Paganetti, a world leader in medical physics at the Massachusetts General Hospital and Harvard Medical School.
As the global push for precision oncology grows, this work highlights the importance of immune system protection by proposing a technological innovation in healthcare that has a tangible impact on patients' quality of life. It raises new questions about how to optimise radiotherapy and its effect on the immune system, as well as how to adjust the duration of sessions or redesign the direction of radiation beams to minimise blood exposure.
The Spanish Research Agency (under the Ministry of Science and Innovation), the Government of Navarra, the "la Caixa" Foundation, the Association of Friends of the University of Navarra, and other institutions supported this research. ts results, as highlighted by Professor Burguete, show that protecting blood plays a crucial role and may prove decisive in how patients respond and recover after cancer treatment. As clinicians incorporate these findings into practice, they may initiate a turning point in therapeutic planning and side-effect management in radiation oncology.
The research was also presented at the Spanish Society of Medical Physics conference held May 27–30, 2025 ( https://congresosefmsepr.es/toledo2025/ ).
Experimental study
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