Description
Proton-Boron Capture Therapy (PBCT) represents a novel strategy based on the proton-boron (pB) fusion reaction to enhance the biological effectiveness of protontherapy (PT) at killing cancer cells. PT promises significant reduction of normal-tissue radiotoxicity, hence of late-occurring complications compared to photon-based conventional radiotherapy (CRT), due to the inverse dose-depth profile (Bragg curve) exhibited by accelerated particles. Therefore, PT would greatly benefit pediatric patients as well as those affected by cancers close to radiosensitive organs, for which abating lifelong elevation of secondary cancer risk or of severe sequalae is imperative. Despite its superior ballistics, PT, however, fails to provide an advantage against radioresistant/aggressive tumors since, at clinically relevant energies (about 200 MeV), protons kill basically the same amount of cancer cells as photons at any given dose. The PBCT approach was proposed to augment tumour local control by PT since the alpha-particles yielded by the pB reaction are radiobiologically highly effective at causing lethal DNA damage.
After reviewing in-vitro experimental evidence supporting the viability of PBCT, future work to be carried out using ELI Beamlines unique ELIMAIA-ELIMED laser-driven proton (LDP) acceleration regimes in combination with proton-triggered nuclear fusion reactions will be illustrated. The extremely high-dose rates achievable in LDP regimes are at the very extreme range of, but still conceptually compatible with those of the so-called FLASH effect, where delivering therapeutic doses in much shorter times than in CTR seems to significantly reduce normal-tissue toxicity. Coupling PBCT with FLASH-like radiobiological response may widen the therapeutic index of PT by further decreasing normal-tissue damage while improving proton biological effectiveness. One application of interest would be specifically in breast cancer, because of the well-established cardiotoxicity associated with CRT and the aggressive phenotype of triple negative breast cancers. This would arguably represent one of the most exciting medical applications of laser-driven pB fusion reaction because of the societal impact it would entail.
