No prior pelvic radiation therapy Any prior pelvic radiation Patients who have received prior pelvic radiation or cytotoxic chemotherapy Plans for pelvic radiation while participating in the study Patients with any prior pelvic radiation therapy. Prior pelvic or abdominal radiation Clinically large pelvic masses reaching above the umbilicus Prior history of abdominal irradiation; patients who have received prior pelvic radiation for colorectal cancer are eligible; however, prior radiation treatment plans must be reviewed prior to enrollment Prior pelvic radiation Patients who have had pelvic or abdominal radiation therapy. Previous pelvic radiation affecting >= % of the bone marrow; patients who received whole pelvic radiation are excluded Patients who had pelvic radiation within months History of abdominal/pelvic radiation therapy No prior pelvic radiation Prior pelvic radiation Any therapeutic pelvic radiation Subjects must not have had prior pelvic radiation therapy History of prior pelvic radiation therapy No prior pelvic radiation therapy or chemotherapy Subject who has undergone a prior pelvic anastomosis. Patients with a history of prior whole pelvic radiation Pelvic radiation therapy Patients who have received prior pelvic radiation Prior history of pelvic radiation therapy Prior pelvic radiation therapy An oncology research protocol requiring full pelvic radiation (i.e., -field box technique) History of pelvic radiation Patients must be considered able to tolerate systemic chemotherapy and pelvic radiation therapy Acute pelvic inflammatory disease No prior radiation to bladder or pelvic region Patients with any prior history of whole pelvic radiation therapy (WPRT) Patients with any prior pelvic surgery Patients with prior history of pelvic fractures or hip replacement Patients must have had a pelvic MRI within days prior to the initiation of treatment Patients undergoing pelvic exenteration History of pelvic radiation History of prior abdominal or pelvic radiation Previously undergone major pelvic surgery Prior pelvic radiation Prior pelvic RT Known or suspected active pelvic infection Prior pelvic radiation for any reason History of pelvic or rectal radiation therapy Patients who have received any prior pelvic radiation therapy in the area of the tumor that precludes the delivery of a curative dose of pelvic radiation Extra-pelvic metastasis on any imaging or biopsy. Prior pelvic radiation Patients who are referred with pelvic symptoms, a known pelvic mass, or a history of prior radiation, will be excluded from this investigation Prior pelvic surgery or radiation History of prior pelvic radiation Prior hip replacement or other major pelvic surgery Prior history of pelvic radiation Has received prior pelvic radiation therapy