TL;DR: Radiation proctitis is a common complication of pelvic radiation therapy that causes rectal bleeding, pain, diarrhoea, and urgency. It affects up to 20% of patients treated for prostate, cervical, rectal, and other pelvic cancers. Hyperbaric oxygen therapy (HBOT) has emerged as one of the most effective treatments for chronic radiation proctitis, with a 10-year retrospective study showing complete or partial response in over 94% of patients. This Daffodil Month, we explain what radiation proctitis is, review the latest clinical evidence for HBOT, and outline how Canadian patients can access treatment.
Estimated reading time: 9 minutes
What Is Radiation Proctitis?
Radiation proctitis is inflammation and damage to the rectum caused by radiation therapy directed at pelvic cancers. When radiation is used to treat prostate cancer, cervical cancer, rectal cancer, bladder cancer, or other pelvic malignancies, the rectum sits in or near the radiation field and absorbs collateral damage.
The condition comes in two forms. Acute radiation proctitis develops during or shortly after treatment and usually resolves on its own within weeks. Chronic radiation proctitis is the more serious form, developing months to years after completing radiation therapy. It is caused by progressive damage to the small blood vessels that supply the rectal lining, leading to tissue that is hypoxic (oxygen-starved), fragile, and prone to bleeding.
Common symptoms of chronic radiation proctitis include:
- Rectal bleeding (haematochezia), sometimes severe enough to require transfusions
- Chronic diarrhoea or loose stools
- Rectal urgency and frequency
- Mucous discharge
- Rectal pain or tenesmus (feeling of incomplete evacuation)
- In severe cases, strictures, fistulae, or bowel obstruction
During Daffodil Month, the Canadian Cancer Society’s annual cancer awareness campaign, it is important to recognise that these lasting effects of cancer treatment are treatable and that effective options exist.
Who Is at Risk?
Chronic radiation proctitis can occur after radiation for any pelvic cancer, but it is most commonly associated with:
| Cancer Type | Estimated Incidence of Chronic Proctitis | Notes |
|---|---|---|
| Prostate cancer | 5-20% | Most common cause due to proximity of rectum to prostate |
| Cervical cancer | 5-15% | External beam and brachytherapy both contribute |
| Rectal cancer | 5-10% | Neoadjuvant radiation before surgery |
| Bladder cancer | 5-10% | Rectum within the radiation field |
| Endometrial cancer | 3-8% | Less common but still significant |
Risk factors include higher radiation dose, larger treatment field, concurrent chemotherapy, pre-existing inflammatory bowel conditions, and diabetes.
How Does HBOT Treat Radiation Proctitis?
Hyperbaric oxygen therapy (HBOT) treats radiation proctitis by addressing the underlying cause of the condition rather than just managing symptoms. Radiation damages the small blood vessels in the rectal wall, creating tissue that cannot heal itself. HBOT works by:
- Angiogenesis: Growing entirely new blood vessels in the irradiated rectal tissue, restoring the oxygen supply that radiation destroyed
- Fibroblast activation: Stimulating collagen-producing cells to strengthen the damaged rectal wall
- Anti-inflammatory effects: Reducing the chronic inflammatory cascade that drives ongoing tissue breakdown
- Mucosal healing: Restoring the protective lining of the rectum by improving the oxygen and nutrient supply to the tissue
Treatment typically involves 40 to 60 sessions at 2.0 to 2.5 ATA, delivered once daily on weekdays. Each session lasts 70 to 90 minutes. Some patients may require more sessions depending on the severity of their condition.
What Does the Clinical Evidence Show?
Radiation proctitis is one of the best-studied indications for HBOT, with evidence from retrospective studies, systematic reviews, and randomised controlled trials.
10-Year Retrospective Cohort (2023)
A 10-year retrospective analysis of 88 patients with radiation-induced proctitis treated with HBOT found that 62.5% achieved a complete clinical response and 31.8% achieved a partial response, for a combined response rate of over 94%. The hematochezia (rectal bleeding) resolution rate was 93.7%. Only 5.7% of patients did not respond to treatment (Monteiro et al., 2023).
94.3% of patients with chronic radiation proctitis achieved a complete or partial response to HBOT in the largest single-centre retrospective study to date.
Cochrane Systematic Review (2023 Update)
The most recent Cochrane review of HBOT for late radiation tissue injury (2023 update, 18 studies, 1,071 participants) found that HBOT may result in complete resolution or significant improvement of late radiation tissue injury, including rectal symptoms. The review noted moderate certainty evidence supporting HBOT for tissues of the head, neck, bladder, and rectum (Lin et al., Cochrane 2023).
Bowel and Bladder Systematic Review (2025)
A 2025 systematic review focused specifically on HBOT for late radiation tissue injury of the bowel and bladder confirmed moderate certainty of beneficial effect. The review included three RCTs with 273 subjects and concluded that there is a weak but positive recommendation for HBOT for rectal complications, with the decision to treat depending on individual patient assessment (Eckert et al., 2025).
Clinically Focused Review (2026)
A landmark 2026 clinically focused review published in CA: A Cancer Journal for Clinicians evaluated HBOT across all chronic radiation-induced conditions, including proctitis. The review provided clinicians with an evidence-informed framework for integrating HBOT into survivorship care and highlighted proctitis as one of the conditions with strongest supporting evidence (Dejonckheere et al., 2026).
Portuguese Real-World Data (2022)
A retrospective analysis of 88 patients with radiation lesions (including 20 with radiation proctitis) treated at a Portuguese hyperbaric unit showed a significant decrease in LENT-SOMA scores across all groups (p < 0.005). The study reinforced that HBOT is an effective therapy for radiation proctitis that has failed conventional treatments (Gaio-Lima et al., 2022).
Quality of Life Data
A 2022 study assessing symptom burden and quality of life six months after HBOT in cancer survivors with pelvic radiation injuries found sustained improvements in patient-reported outcomes, confirming that HBOT benefits extend beyond the immediate treatment period (QoL Study, 2022).
How Does HBOT Compare to Other Treatments?
Several treatments are used for chronic radiation proctitis, each with different mechanisms and evidence levels:
| Treatment | Mechanism | Evidence Level | Notes |
|---|---|---|---|
| HBOT | Angiogenesis, tissue regeneration | RCTs, systematic reviews | Addresses underlying cause; sustained response |
| Argon plasma coagulation (APC) | Cauterises bleeding vessels | Case series | Symptom management; may need repeat sessions |
| Rectal formalin | Chemical cauterisation | Case series | For bleeding only; can cause complications |
| Sucralfate enemas | Protective mucosal barrier | RCTs (mixed results) | No consistent benefit in controlled trials |
| Oral medications | Varies | Limited RCTs | A systematic review found limited evidence for most oral drugs |
A 2023 systematic review of oral drugs for chronic radiation proctitis found that sucralfate showed no significant difference versus placebo, highlighting the need for more effective therapies like HBOT that address the root cause of tissue damage.
Is HBOT Covered for Radiation Proctitis in Canada?
Delayed radiation injury, including radiation proctitis, is one of the 14 UHMS-approved indications for HBOT and one of the most widely covered indications across Canadian provinces:
- Ontario: OHIP covers HBOT for delayed radiation injury at both hospital-based programs and approved independent facilities
- Alberta: Covered at hospital-based AHS clinics and CPSA-accredited private facilities
- Quebec, British Columbia, Nova Scotia, and Newfoundland: Covered at hospital-based facilities for approved indications
- Manitoba, Saskatchewan: Hospital-based coverage available
- Other provinces: Interprovincial referral may be available for patients without local facilities
For a complete province-by-province breakdown, visit the Canada Hyperbarics coverage guide. To find a hospital or regulated facility near you, use the facility finder with postal code search.
Frequently Asked Questions
How long after radiation can proctitis develop?
Chronic radiation proctitis typically develops 3 months to several years after completing pelvic radiation therapy. Some patients do not experience symptoms until 5 or more years after treatment. The progressive nature of radiation vascular damage means that symptoms can appear or worsen over time.
How many HBOT sessions are needed for radiation proctitis?
A standard protocol involves 40 to 60 sessions at 2.0 to 2.5 ATA, delivered once daily on weekdays. The 10-year retrospective study found that partial and complete responses for overall symptoms required fewer than 70 sessions, while isolated hematochezia (rectal bleeding) tended to require at least 70 sessions. Your hyperbaric medicine team will monitor your progress and adjust the treatment plan.
Does HBOT work when other treatments have failed?
Yes. Many patients referred for HBOT have already tried other treatments such as argon plasma coagulation, formalin, or medications without adequate relief. The Portuguese real-world study specifically evaluated patients with radiation lesions refractory to medical and endoscopic treatments and found HBOT to be effective in this population.
Can radiation proctitis come back after HBOT?
The RICH-ART trial (which studied radiation cystitis, a closely related condition) found that HBOT benefits were sustained over 5 years, with only 12.8% of patients requiring additional HBOT for recurring symptoms. While proctitis-specific long-term data is more limited, the mechanism of HBOT (growing new blood vessels) produces durable structural improvements in the tissue.
This Daffodil Month, Seek Help for Radiation Effects
Radiation proctitis is a recognised medical condition with effective, evidence-based treatment available at hospitals and regulated facilities across Canada. If you underwent pelvic radiation therapy and are living with rectal bleeding, bowel changes, or chronic pain, talk to your oncologist or family physician about a referral for HBOT assessment.
Find a hyperbaric facility near you across Canada.
This April, in recognition of Daffodil Month, Canada Hyperbarics is dedicated to helping cancer survivors understand and access treatments for the lasting effects of cancer therapy.
References
- Monteiro AM, Alpuim Costa D, Mareco V, Espiney Amaro C. The effectiveness of hyperbaric oxygen therapy for managing radiation-induced proctitis – results of a 10-year retrospective cohort study. Frontiers in Oncology. 2023. View in Canada Hyperbarics Research Database.
- Lin ZC, Bennett MH, et al. Hyperbaric oxygen therapy for late radiation tissue injury. Cochrane Database of Systematic Reviews. 2023. View in Canada Hyperbarics Research Database.
- Eckert KA, Fife CE, Carter MJ. Systematic review of hyperbaric oxygen for late radiation tissue injury (bowel, bladder). Undersea & Hyperbaric Medicine. 2025. View in Canada Hyperbarics Research Database.
- Dejonckheere CS, et al. Hyperbaric oxygen therapy for chronic radiotherapy-related adverse effects: a clinically focused review. CA: A Cancer Journal for Clinicians. 2026. View in Canada Hyperbarics Research Database.
- Gaio-Lima C, et al. The role of hyperbaric oxygen therapy in the treatment of radiation lesions. Clinical and Translational Oncology. 2022. View in Canada Hyperbarics Research Database.
- Symptom burden and health-related quality of life six months after hyperbaric oxygen therapy in cancer survivors with pelvic radiation injuries. 2022. View in Canada Hyperbarics Research Database.
- Liu L, Xiao N, Liang J. Comparative efficacy of oral drugs for chronic radiation proctitis – a systematic review. Systematic Reviews. 2023. View in Canada Hyperbarics Research Database.
This content is for informational purposes only and does not constitute medical advice. Hyperbaric oxygen therapy should only be administered by qualified healthcare professionals in accredited facilities. Consult your physician or a certified hyperbaric medicine specialist for treatment decisions. Canada Hyperbarics is an independent educational resource and is not affiliated with any specific clinic or manufacturer.