Proton beam therapy in rectal cancer: A systematic review and meta-analysis.

Introduction: Locally advanced rectal cancer is often treated with neoadjuvant chemoradiotherapy and surgery. Radiotherapy carries significant risk of toxicity to organs at risk (OAR). Proton beam therapy (PBT) has demonstrated to be effective in other cancers, delivering equivalent dosimetric radiation but with the benefit of improved sparing of OAR.