Modern-day breast cancer radiotherapy has advanced significantly, prioritizing both effectiveness and safety. With existing x-ray/photon treatments like intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), precise targeting of tumor sites while sparing nearby healthy tissues such as the heart and lungs are already available. Proton beam therapy (PBT) is emerging as a promising option in the treatment of breast cancer, particularly in scenarios where minimizing radiation exposure to surrounding organs is crucial. Currently in Singapore, breast cancer proton beam therapy is not indicated as mandated by the Ministry as the clinical evidence for significant usefulness and cost-effectiveness data are not yet widely available. In selected patients who may benefit from this treatment, a dedicated tumour board and clinical ethics committee is necessary to facilitate the approval.