Proton therapy minimizes the effects of radiation on the immune system, reduces lymphopenia and improves survival.

With clinical experience of the largest number of patients treated in Spain, Dr. Rosa Meirinhospecialist Proton Therapy Department of the Oncology Center of the University Clinic of Navarra (CCUN)spoke at the 62nd annual meeting of the Particle Therapy Cooperative Group (PTCOG), held recently in Singapore, with a presentation in which he highlighted the benefits of protecting the immune system of those exposed to this type of external radiation.

One of the main advantages of proton therapy is preservation of various healthy tissues surrounding the tumor and its impact on future quality of life, especially in pediatric patients. However, another important benefit for patients is the reduction of lymphopenia, a decrease in the number of lymphocytes in the peripheral blood that can be observed in the acute infectious phase, in severe immunodeficiency and after treatment with cytostatics. In this sense, Dr. Meyrinho emphasized that “after proton irradiation, there is less radiation-induced lymphopenia than with photon therapy, and this leads to benefits for the entire immune system.”

“The impact of radiation lymphopenia is important in the outcome of cancer treatment. There are studies that highlight a detrimental relationship between grade 3 or higher lymphopenia and overall survival in patients receiving radiation therapy for solid tumors, especially those located in the brain, chest, or upper abdomen. Any strategy that can help us mitigate this blood disorder in these cases will be helpful in improving survival,” said the CCUN proton therapy specialist.

Dr. Meyrigno’s presentation included findings from a study of 43 patients, some of whom received proton therapy and others photon therapy. The analysis confirmed that “patients with thoracic and abdominal tumors irradiated with proton therapy were associated with a lower effective dose to circulating immune cells and statistically higher lymphocyte counts in peripheral blood.”

Phase II of the VASA project

The results presented in this Asian edition of PTCOG include preliminary findings from the CCUN-led VASA project, which uses biomarkers to analyze the effects of radiotherapy on vascular structures and circulating blood during therapeutic radiation treatments required for cancer patients.

The project also focuses on proposals for changes in daily clinical practice to vary dosimetric planning of oncological radiation treatments, predict the impact on immunocompetence, adapt it and prevent other health problems in order to reduce side effects and increase potential cancer-free survival.

Dr. Meyrinho believes that “a systematic study of the effects of radiation on blood vessels and circulating blood in clinical practice may open up new possibilities for optimizing radiation therapy planning. This would represent a significant paradigm shift in healthcare practice. “Immunocompetence can be enhanced if measures are taken to minimize unnecessary irradiation of vascular structures,” a reality that proton therapy facilitates.