Proton Therapy for Breast Cancer: When is it useful?
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.
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.
X-ray treatments with combined with Image-guided radiotherapy (IGRT) further ensures accurate delivery by accounting for patient movement during treatment. Safety protocols and innovations, such as deep inspiration breath-hold (DIBH) for left-sided breast cancer, minimize radiation exposure to critical organs, significantly reducing the risk of long-term complications like cardiac and pulmonary damage. Together, these advancements enhance outcomes and improve the overall quality of life for breast cancer patients
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. According to findings from the Particle Therapy Cooperative Group (PTCOG) Breast Subcommittee, proton therapy is most beneficial for patients who require
- left-sided regional nodal irradiation with existing cardiac risk factors (older age, hypertension, cholesterolemia, previous myocardial events, diabetes etc)
- have complex anatomy (pectus excavatum),
- or are undergoing reirradiation.
- bilateral breast cancers
- recontruction
- have hereditary mutations that increase risk of cancers ( excluding BRCA )
The precision of proton therapy enables it to deliver targeted radiation to cancerous tissues while sparing critical structures like the heart and lungs, reducing the risks of long-term complications. This makes it especially relevant for patients with left-sided breast cancer, bilateral breast cancer, or those who have undergone breast reconstruction.
While PBT offers these advantages, it comes with higher costs and logistical considerations. Ongoing research and clinical trials aim to refine patient selection criteria and evaluate its cost-effectiveness, ensuring that the benefits outweigh the challenges.
Currently clinical trials are ongoing in the European Union, and prospective observational studies are being conducted.
For more details, you can refer to the PTCOG Breast Subcommittee’s consensus statement and ongoing studies on this topic