Proton therapy in breast cancer: bridging medical and radiation oncology

Breast cancer remains the most common malignancy among women globally, and postoperative radiotherapy (PORT) is essential for improving local control and overall survival. Proton therapy (PT) is emerging as an alternative to conventional radiotherapy due to its ability to reduce dose exposure to healthy tissues. It could be of particular use in patients requiring radiotherapy to the internal mammary chain, a population that is likely to also be undergoing systemic therapy as part of their breast cancer treatment. This review evaluates current preclinical and clinical data on the integration of PT with systemic treatments in the setting of breast cancer, highlighting its potential role to improve therapeutic outcomes while reducing toxicity. The findings of this review highlight PT’s potential to minimize side effects, particularly cardiotoxicity and potentially to enhance the efficacy of systemic treatments such as immunotherapy.