Physics and biology are closely related in radiation therapy. By changing the physical parameters of the irradiation, i.e. the dose delivery methods, the biological response of both normal and tumoral tissues may be modified and this change can potentially be exploited for the patient’s benefit. Along this line, the highly spatially modulated dose distributions in minibeam radiation therapy (MBRT) have been shown to lead in small animal experiments to significant tumor control as well as to a reduction in normal tissue toxicities [1]. It should be noted tumor control is achieved despite using highly heterogeneous dose distributions with very low valley doses contradicting the classical paradigm of conventional radiotherapy, These observations cannot be explained with classical radiobiology concepts. Indeed, there is increasing evidence that MBRT effects may go beyond simple tumor cell death, and that the so-called non targeted effects, such as bystander effects as well as stromal and immunological changes, may play a major role in radiation response in MBRT [1]. The strategy in MBRT, “divide and conquer”, provides a very different angle of attack from conventional radiation, which can be a game changer for many difficult-to-treat cases today. This lecture will provide an overview of the state of the art of MBRT, focusing on the most recent data, to show how the field has become mature to proceed to the first clinical treatments performed recently at Mayo Clinic [2]
1. Prezado, Y., et al., Spatially fractionated radiation therapy: a critical review on current status of clinical and preclinical studies and knowledge gaps. Phys Med Biol, 2024. 69(10).
2. Grams, M.P., Minibeam radiation therapy treatment (MBRT): commissioning and first clinical implementation. International Journal Radiation Oncology, Biology, Physics, 2024. in press.