The advent of proton beam therapy (PBT) brings new promise of reduced radiation treatment related morbidity by minimizing the dose to critical normal tissues . Proton therapy has shown great therapeutic potential in treating various adult malignancies including the central nervous system and gastrointestinal tract, but with uncertain benefits for example for lung cancers. At the same time, it has been estimated that excess fatal SPCs may be further reduced with proton therapy by two-thirds compared to conventional photon therapy . However, evidence that PBT reduces occurrence of metachronous cancers is limited. A study looking at PBT for advanced cholangiocarcinomas showed gastrointestinal toxicities and early metastatic progression still remains a treatment obstacle . Another study looking at cardiac events post RT in patients with thymic malignancies, showed that the lower dose to organs with PBT reduced the occurrence of major cardiac events post treatment . A long-term follow-up of patients with pediatric tumors showed fewer late adverse events and a reduced risk of metachronous malignancies with PBT . Similar studies seem to indicate that the reduced dose to normal structures with PBT as opposed to intensity-modulated RT is better tolerated by the patient population . But, it may be too soon to draw a conclusion on the benefits of PBT over traditional photon RT. A study comparing RT usage trends in men with localized prostate cancers pointed differences in demographic and prognostic factors between patients treated with proton and photon RT . Thus, although the physical theory of it may indicate to clear benefits, there is a need for more long-term assessments and more studies in general looking at the potential profits of PBT over traditional RT.