Lower gastrointestinal (LGI) tract malignancies arise from the rectum and anal canal. The PTCOG GI Subcommittee conducted a systematic literature review, and provided strong recommendations for the use of PBT in treatment of LGI selected patients including 1) patients requiring reirradiation for local-regional recurrence, 2) patients in whom critical structure dose constraints cannot be met with other radiation modalities, 3) patients with pelvic or transplanted kidneys within or near the target volume, 4) adolescent and young adult (AYA)/young patients, 5) patients with active inflammatory bowel disease (Crohn’s, ulcerative colitis, etc.), 6) patients with genetic syndromes predisposing them to development of radiation-induced secondary malignancy, making total volume of radiation minimization crucial, 7) patients who need to preserve ovarian function and fertility, and 8) patients enrolled on a prospective clinical trial. This consensus statement also provides considerations for treatment planning and delivery.