Patients will be randomized into two groups of spot placement. In the experimental arm, "Spot Delete" will be used to prohibit proton spots from being placed in the rectum, sigmoid, and small bowel. In the control arm, proton spots are placed by the treatment planning system are not modified. Medical staff will document gastrointestinal toxicities (diarrhea, fecal incontinence, proctitis, and rectal hemorrhage) and genitourinary toxicities (hematuria, urinary incontinence, urinary retention, urinary obstruction, urinary pain, urinary frequency, and urinary urgency) in the electronic medical record.
This study carries the same risks as regular proton therapy. Proton therapy, like other cancer treatments, may cause the aforementioned side effects. It is important to note that the "Spot Delete" technique aims to specifically address the bladder and bowel reactions, so there might be a potential reduction in this particular risk. Dose constraints will be the same for each treatment arm. Though not expected, it is theoretically possible that this method may counterintuitively increase side effects involving the bladder or bowel. Likewise, increased side effects in other organs are not expected, but are theoretically possible. For this reason we believe there is clinical equipoise between the two trial arms.
