Proton therapy for thoracic reirradiation of non-small cell lung cancer

Lung cancer is a leading cause of cancer death with frequent local failures after initial curative-intent treatment. Locally recurrent non-small cell lung cancer represents a challenging clinical scenario as patients have often received prior radiation as part of a definitive treatment regimen. Proton beam therapy, through its characteristic Bragg peak and lack of exit dose is a potential means of minimizing the toxicity to previously irradiated organs and improving the therapeutic ratio. This article aims to review the rationale for the use of proton beam therapy for treatment of locally recurrent non-small cell lung cancer, highlight the current published experience on the feasibility, efficacy, and limitations of proton beam reirradiation, and discuss future avenues for improved patient selection and treatment delivery.