TLDR: Radiation proctitis is rectal inflammation after pelvic radiation for cancers such as prostate, cervical, uterine, bladder, or rectal cancer. Acute symptoms often settle after treatment. Chronic radiation proctitis can start months to years later, with bleeding, urgency, diarrhea, and pain. Undersea and Hyperbaric Medical Society indications include delayed radiation injury of soft tissue. A randomized crossover trial (HORTON) found hyperbaric oxygen improved healing versus sham, with an absolute risk reduction of 32% and a number needed to treat of 3. OxygenWell delivers medical-grade oxygen in monoplace chambers up to 2.4 ATA in Sherman Oaks and Calabasas. Insurance may cover on-label delayed radiation injury after medical review.
What is radiation proctitis?
Radiation proctitis is inflammation of the rectum after radiation aimed at the pelvis. The National Cancer Institute notes it is most common after radiation for rectal, prostate, and cervical cancers, and it can be acute or chronic. Acute disease starts during or soon after radiation and often eases within weeks. Chronic disease can last, with rectal pain, bleeding, and loss of bowel control. See the NCI radiation proctitis overview.
Cleveland Clinic reports chronic radiation proctitis in up to 20% of people who receive pelvic radiation. Acute symptoms include diarrhea (sometimes bloody), cramping, urgency, tenesmus, mild bleeding, and mucus. Chronic disease can add stricture, ulcers, and fistula. See Cleveland Clinic.
StatPearls classifies radiation proctitis as a form of delayed soft-tissue radiation injury: obliterative endarteritis, ischemia, fibrosis, atrophy, and telangiectasia. It usually appears 6 months to several years after exposure. Incidence of chronic disease after pelvic doses above 5,000 cGy is often cited at 1% to 5%, with some series higher. See StatPearls: Hyperbaric Treatment of Radiation Proctitis.
How does hyperbaric oxygen help irradiated rectal tissue?
Irradiated rectal mucosa is poorly oxygenated. Hyperbaric oxygen raises dissolved oxygen in plasma under increased pressure. StatPearls describes angiogenesis, re-epithelialization, and collagen support in ischemic irradiated tissue. The American Society of Colon and Rectal Surgeons clinical practice guidelines recommend HBOT as an effective option to reduce bleeding in chronic radiation proctitis (strong recommendation, moderate-quality evidence), as summarized in that same StatPearls review.
This is the same delayed-radiation biology OxygenWell covers for the jaw in the Marx Protocol for osteoradionecrosis and for bladder injury in HBOT for radiation cystitis. Rectal injury sits in the same FDA-recognized delayed radiation injury family as soft tissue radionecrosis.
What did the HORTON trial show?
Clarke and colleagues published a multicenter, randomized, double-blind, crossover trial in the International Journal of Radiation Oncology, Biology, Physics (2008). Patients with refractory radiation proctitis received oxygen at 2.0 ATA or sham air at 1.1 ATA. Of 226 screened, 150 enrolled and 120 were evaluable. After the first allocation, mean SOMA-LENT scores improved more with true HBOT (5.00 vs 2.61; p = 0.0019). Clinical responders were 88.9% vs 62.5% (p = 0.0009). The authors reported an absolute risk reduction of 32% and a number needed to treat of 3. Quality-of-life bowel bother scores favored HBOT. Differences disappeared after crossover, which is what you expect if the sham group later received real treatment. Abstract: PubMed; full article: ScienceDirect.
StatPearls also notes a 10-year retrospective series with complete symptom resolution in 62% and at least partial resolution in 94%, and cites symptom relief near 89% lasting 6 to 12 months in selected reports. Those figures come from the literature summary, not a single new trial, so treat them as supporting context around HORTON, not a substitute for it.
How many sessions does radiation proctitis usually need?
StatPearls states successful resolution typically needs 30 to 40 sessions, with courses often 20 to 30 sessions at 2 to 2.5 ATA for 60 to 120 minutes per day. Some patients need 30 to 60 sessions based on severity. OxygenWell protocols for delayed radiation injury commonly use 2.0 to 2.4 ATA with medical-grade oxygen by non-rebreather mask in grounded monoplace chambers. Your referring oncologist or GI specialist and the hyperbaric evaluation set the plan. Do not treat session count as a guarantee.
Where does HBOT sit among other treatments?
Cleveland Clinic lists first steps for mild disease: rehydration, NSAIDs, stool softeners, antispasmodics. More severe care can include sucralfate enemas, formalin, rectal corticosteroids, argon plasma coagulation, hyperbaric oxygen, or surgery (ileostomy, colostomy, or resection). StatPearls notes sucralfate enemas as a preferred first-line local option, and HBOT as adjunct or next step after local or endoscopic care fails. Bowel surgery in irradiated tissue carries high complication rates in some series (over 70%). Preoperative HBOT can lower those risks when surgery is unavoidable.
NCI focuses acute care on symptom relief, small frequent meals, and diet support. Chronic bleeding, transfusion need, or failed endoscopy is when hyperbaric referral is most useful.
Who should consider HBOT in Los Angeles?
Consider evaluation if you had pelvic radiation and still have rectal bleeding, urgency, mucus, pain, or anemia months or years later. Exclude cancer recurrence first. StatPearls warns that biopsies of irradiated rectum can cause necrosis or fistula; endoscopy belongs with GI, and biopsy is not a casual diagnostic step.
OxygenWell sees patients at Sherman Oaks and Calabasas. Veterans with delayed radiation injury may use Community Care; see VA Community Care for delayed radiation injury. PPO and Medicare may cover FDA-recognized delayed radiation injury after documentation. Call (818) 661-0939 or use oxygenwell.com/contact.
Safety notes
StatPearls lists untreated pneumothorax as a contraindication. Ear barotrauma is the most common side effect. Recent doxorubicin or bleomycin is a hard stop without oncology clearance. Active cancer is not, by itself, a contraindication in that review, though every case still needs oncology coordination.
Next step
If rectal bleeding or urgency after pelvic radiation has not settled with enemas or endoscopy, ask your GI or radiation oncologist about a hyperbaric consult. OxygenWell can review records, confirm whether the indication is on-label delayed radiation injury, and outline a session plan for Sherman Oaks or Calabasas.
