How Hyperbaric Oxygen May Support Healing After Delayed Radiation Damage to the Bladder, Bowel, Bone, Skin, and Other Tissues
Radiation therapy is essential to the treatment of many cancers, but its effects are not limited to malignant cells. Normal tissue within or near the treatment field may sustain vascular, cellular, and structural injury that becomes clinically apparent months or years after cancer therapy has ended.
Hyperbaric oxygen therapy, commonly abbreviated as HBOT, is used as an adjunct for selected delayed radiation injuries involving soft tissue or bone. The goal is not to remove radiation from the body or reverse every late effect. HBOT is intended to improve oxygen delivery and support vascular repair within viable tissue that has become chronically hypoxic, fibrotic, fragile, or unable to heal normally.
The Undersea and Hyperbaric Medical Society recognizes delayed radiation injury involving soft tissue and bone as an accepted hyperbaric indication. Medicare also covers osteoradionecrosis and soft tissue radionecrosis when HBOT is used alongside conventional treatment. (UHMS)
Acute and Delayed Radiation Injuries Are Different
Acute radiation effects develop during treatment or shortly afterward. Depending on the treatment field, these may include skin irritation, mucositis, diarrhea, urinary frequency, fatigue, or inflammation.
Delayed radiation tissue injury develops later, sometimes after a long symptom-free interval. It reflects progressive changes within irradiated blood vessels, connective tissue, bone, and organ walls. The tissue may become less vascular, less cellular, more fibrotic, and less able to respond to trauma or infection. (Cochrane)
A minor event may reveal the underlying damage. Examples include:
- A dental extraction followed by exposed jawbone
- A cystoscopy or urinary infection followed by recurrent bladder bleeding
- Surgery within an irradiated field followed by wound breakdown
- Minor trauma followed by chronic ulceration
- Progressive rectal bleeding years after pelvic radiation
HBOT is generally directed toward delayed injury rather than ordinary acute radiation side effects. Acute symptoms still require evaluation by radiation oncology and the relevant organ specialist.
Why Irradiated Tissue May Fail to Heal
Radiation can damage small blood vessels and alter the normal balance of inflammation, fibrosis, and tissue repair. Over time, the affected area may develop reduced capillary density, chronic hypoxia, stromal fibrosis, and limited regenerative capacity.
The resulting tissue may appear intact at rest but fail when placed under additional stress. Surgery, infection, pressure, dental extraction, or mechanical trauma can create an oxygen demand that the damaged circulation cannot meet.
Clinical consequences may include:
- Persistent ulceration
- Recurrent bleeding
- Tissue necrosis
- Fibrosis and restricted movement
- Bone exposure
- Infection
- Fistula formation
- Surgical wound breakdown
- Failure of grafts or flaps
The injury is often progressive. Treating only the visible wound or bleeding vessel may provide temporary control without correcting the underlying vascular deficiency.
How HBOT Supports Radiation Injury Recovery
During HBOT, the patient breathes oxygen while exposed to increased atmospheric pressure. This markedly raises arterial oxygen tension and increases the amount of oxygen dissolved directly in plasma.
The immediate increase in tissue oxygen is temporary. The larger therapeutic objective is to create repeated oxygen exposures that stimulate repair processes within viable irradiated tissue.
Potential effects include:
- Improved oxygen diffusion into hypoxic tissue
- Support for endothelial and fibroblast activity
- Promotion of angiogenic signaling
- Development of new capillary networks
- Improved collagen production and organization
- Support for epithelial repair
- Improved oxygen-dependent immune function
- Greater resistance to recurrent tissue breakdown
HBOT does not remove established scar tissue or restore tissue that is already completely necrotic. Its benefit depends on the presence of viable cells and enough circulation to deliver oxygenated plasma into the injured area. (NCBI)
Radiation Cystitis Has Some of the Strongest Evidence
Radiation cystitis can occur after treatment for prostate, bladder, cervical, endometrial, rectal, or other pelvic cancers.
Patients may experience:
- Visible or microscopic hematuria
- Clot retention
- Urinary frequency
- Urgency
- Dysuria
- Pelvic discomfort
- Incontinence
- Reduced bladder capacity
- Recurrent hospitalization or transfusion
Before symptoms are attributed to radiation, patients generally require a urologic evaluation appropriate to their presentation. Infection, stones, anticoagulation, upper urinary tract disease, recurrent cancer, and a new urothelial malignancy may produce similar symptoms.
HBOT is intended to improve the condition of the bladder wall rather than simply stop bleeding for the duration of one treatment. It is commonly considered after radiation injury has been documented and symptoms remain significant despite appropriate urologic care.
Long-Term Findings From the RICH-ART Trial
The randomized RICH-ART trial compared HBOT with standard care in patients with chronic urinary symptoms after pelvic radiation. Participants assigned to HBOT received 30 to 40 treatments at approximately 2.4 to 2.5 atmospheres absolute for 80 to 90 minutes per session.
The original trial demonstrated significantly greater improvement in patient-reported urinary symptoms after HBOT. Five-year follow-up published in 2025 found that the mean improvement in the urinary symptom score remained stable among the followed patients, supporting the possibility of durable benefit rather than only temporary symptom suppression. (PubMed)
The trial did not represent every patient with hemorrhagic radiation cystitis. It excluded patients with certain severe findings, including recent bleeding requiring substantial transfusion, permanent catheter dependence, bladder capacity below 100 mL, and bladder fistula. Outcomes should therefore not be generalized automatically to patients with a severely contracted, fistulizing, or structurally nonfunctional bladder. (PubMed)
HBOT may reduce hematuria and urinary symptom burden, but some patients still require clot evacuation, fulguration, embolization, urinary diversion, or cystectomy.
Radiation Proctitis and Bowel Dysfunction Require Careful Selection
Pelvic radiation can injure the rectum and lower bowel, producing:
- Rectal bleeding
- Urgency
- Tenesmus
- Mucus discharge
- Diarrhea
- Pain
- Incontinence
- Ulceration
- Stricture or fistula
The evidence for HBOT in lower bowel radiation injury is mixed. The 2023 Cochrane review found some evidence of benefit in selected patients with late radiation injury involving the rectum, but it emphasized small studies, variable methods, and uncertainty about which patients are most likely to respond. (Cochrane)
The sham-controlled HOT2 trial did not demonstrate a significant benefit from HBOT for its primary outcomes in patients with chronic bowel dysfunction after pelvic radiation. This negative trial is important because radiation-related bowel symptoms can result from several different processes, not all of which are likely to respond to increased tissue oxygenation. (PubMed Central (PMC))
A gastroenterology or colorectal evaluation may be needed to distinguish:
- Bleeding telangiectasia
- Ulceration
- Fibrotic stricture
- Fistula
- Malabsorption
- Bile acid dysfunction
- Pelvic floor dysfunction
- Recurrent malignancy
- Inflammatory or infectious disease
HBOT may be more biologically relevant to documented ischemic ulceration or soft tissue radionecrosis than to nonspecific bowel frequency or functional symptoms without clear tissue injury.
Osteoradionecrosis Requires Multidisciplinary Management
Osteoradionecrosis occurs when irradiated bone loses viability and fails to heal. It most commonly affects the mandible after head and neck radiation, although other bones within a treatment field may also be involved.
Potential findings include:
- Exposed bone
- Persistent oral or facial pain
- Drainage
- Swelling
- Pathologic fracture
- Fistula
- Dental instability
- Infection
- Difficulty chewing or swallowing
Management may include oral hygiene, antibiotics when infection is present, limited debridement, removal of sequestra, reconstructive surgery, vascularized tissue transfer, and selected medical therapies.
HBOT has historically been incorporated into protocols for mandibular osteoradionecrosis and dental surgery in irradiated bone. Contemporary guidance is more cautious. The 2024 ISOO-MASCC-ASCO guideline concluded that evidence supporting routine HBOT for prevention or management of jaw osteoradionecrosis remains limited and that its use is largely unjustified as an automatic standard for every patient. (ASCO Publications)
This does not mean HBOT has no role in head and neck radiation injury. It means treatment should be individualized rather than based solely on a history of radiation or a planned dental extraction.
Consultation may still be reasonable when:
- Established bone and soft tissue radionecrosis coexist
- Previous conservative treatment has failed
- A substantial reconstruction is planned
- The wound bed is markedly hypoxic
- The surgeon and hyperbaric physician define a specific objective
- Other reconstructive options are limited
HBOT should not replace removal of necrotic bone, infection management, stabilization of a pathologic fracture, or oncologic evaluation.
Radiation Injury of the Breast and Chest Wall
Breast and chest wall radiation may produce late pain, fibrosis, edema, skin changes, tissue tightness, and reduced shoulder mobility.
A 2024 randomized clinical trial evaluated 30 to 40 HBOT sessions in women with late local effects following breast irradiation. Offering HBOT did not significantly reduce the primary pain outcome in the intention-to-treat analysis, although fibrosis was reduced. Patients who completed treatment showed stronger signals of reduced pain and fibrosis, but only a minority of those offered HBOT completed the course. (PubMed)
These findings highlight two important limitations:
- Treatment burden can substantially affect participation.
- Different late effects may respond differently.
Fibrosis, pain, edema, and movement restriction should not be treated as one interchangeable condition. A patient may also need physical therapy, lymphedema treatment, pain management, reconstructive evaluation, or assessment for recurrent cancer.
HBOT may be considered for selected breast or chest wall radiation injuries, but expectations should remain tied to the specific symptom and tissue abnormality being treated.
Skin and Soft Tissue Radionecrosis
Soft tissue radionecrosis may present as chronic ulceration, drainage, pain, bleeding, fibrosis, or wound breakdown within a previous radiation field.
Common sites include:
- Head and neck
- Chest wall
- Pelvis and perineum
- Abdominal wall
- Extremities
- Surgical incisions within irradiated tissue
A new ulcer or mass in a previous cancer field should not automatically be labeled radionecrosis. Evaluation may require imaging, biopsy, cultures, vascular assessment, or specialist review to exclude recurrent malignancy, infection, pressure injury, or another cause.
HBOT may be appropriate when viable irradiated tissue remains but cannot heal because of chronic vascular injury and hypoxia. The visible wound still requires local care, debridement when appropriate, infection management, nutrition, pressure relief, and reconstruction planning.
HBOT Around Surgery in Irradiated Tissue
Surgery within an irradiated field can be difficult because tissue may have limited blood flow, reduced elasticity, and impaired healing capacity.
HBOT may be considered before and after selected operations when the surgical team believes that improving the tissue environment could reduce wound breakdown or support reconstruction. Potential scenarios include:
- Debridement of established radionecrosis
- Reconstruction of a chronic radiation wound
- Grafting or flap placement into irradiated tissue
- Surgery involving both bone and soft tissue injury
- Repair after previous wound failure
The 2023 Cochrane review found low-certainty evidence that HBOT may reduce wound dehiscence following some head and neck soft tissue operations in irradiated patients. The review also emphasized uncertainty regarding optimal patient selection, timing, and dose. (Cochrane)
No universal preoperative and postoperative schedule should be applied to every patient with prior radiation. Historical protocols remain influential, but modern surgery, radiation planning, vascularized reconstruction, and updated guidelines have changed the decision framework.
The surgeon and hyperbaric physician should agree on:
- The diagnosis being treated
- Whether viable tissue remains
- The purpose of preoperative treatment
- The timing of surgery
- The number of postoperative treatments
- Criteria for stopping or modifying the plan
Treatment Protocols Vary by Organ and Objective
Common delayed radiation injury protocols involve treatment once daily, five days per week, at approximately 2.0 to 2.5 atmospheres absolute. Oxygen exposure often lasts 80 to 120 minutes, and many courses involve approximately 30 to 40 sessions.
The RICH-ART protocol used 30 to 40 sessions at 2.4 to 2.5 atmospheres absolute for 80 to 90 minutes. Broader published protocols for soft tissue radionecrosis commonly fall within a similar general range, although treatment may be adjusted for the organ involved, clinical response, surgical plan, and patient tolerance. (PubMed)
A treatment course should not continue automatically because a certain number of sessions was initially authorized. Reassessment should consider:
- Symptom change
- Bleeding frequency
- Wound appearance
- Tissue viability
- Pain and function
- Surgical readiness
- Adverse effects
- Whether the original treatment goal remains achievable
Recovery may become apparent gradually. Angiogenic and reparative changes require repeated exposure and may continue to influence healing after the chamber course ends.
What Recovery May Look Like
Radiation injury recovery does not always mean complete restoration of normal tissue.
Meaningful improvement may include:
- Reduced bladder or rectal bleeding
- Fewer clot-retention episodes
- Reduced transfusion requirements
- Improved urinary frequency or urgency
- Healing of a chronic ulcer
- Improved tissue quality before surgery
- Reduced wound breakdown after reconstruction
- Reduced pain
- Greater tolerance of dental or surgical procedures
- Preservation of tissue or organ function
Some patients experience partial rather than complete improvement. Fibrosis, structural narrowing, fistulas, advanced bone destruction, or severe loss of organ capacity may not resolve with HBOT alone.
The treatment objective should be established before therapy begins so that the patient and clinical team can judge whether meaningful recovery is occurring.
Current Evidence Supports Selective Use
The 2023 Cochrane review included 18 randomized studies with 1,071 participants. It found low- to moderate-certainty evidence that HBOT may improve outcomes in selected late radiation injuries involving the head and neck, bladder, and rectum. It also found possible reductions in wound dehiscence and modest improvement in pain following head and neck radiation. (Cochrane)
The evidence remains limited by:
- Small study populations
- Differences in treated organs
- Variable injury severity
- Different chamber protocols
- Inconsistent outcome definitions
- Limited long-term follow-up
- Difficulty creating a credible sham treatment
Evidence should therefore be interpreted by organ and clinical phenotype. Strong findings in radiation cystitis should not be transferred automatically to bowel dysfunction, mandibular osteoradionecrosis, breast fibrosis, or every chronic symptom following cancer treatment.
HBOT Does Not Treat Recurrent Cancer
HBOT is directed toward normal tissue damaged by radiation. It is not a treatment for residual or recurrent malignancy.
Before therapy, clinicians should investigate suspicious findings such as:
- A new mass
- Progressive ulceration
- Unexplained bleeding
- New bone destruction
- Weight loss
- Enlarging lymph nodes
- Symptoms inconsistent with the expected radiation field
Biopsy may be necessary when recurrent cancer cannot be excluded.
A history of treated cancer does not automatically prohibit HBOT. The decision should involve the relevant oncology team when active disease, ongoing systemic therapy, or uncertainty about recurrence is present.
Safety Screening and Treatment Burden
HBOT is generally well tolerated in qualified medical facilities, but potential adverse effects include:
- Middle-ear or sinus barotrauma
- Temporary nearsightedness
- Claustrophobia
- Blood glucose changes
- Pulmonary pressure injury
- Rare oxygen-induced seizure
The Cochrane review found increased risks of temporary visual-acuity reduction and ear barotrauma in treated patients. (Cochrane)
An untreated pneumothorax must be addressed before pressurization. Significant pulmonary disease, inability to equalize ear pressure, seizure risk, implanted devices, cardiac instability, and medication interactions require individualized assessment.
Treatment burden is also substantial. A course of 30 to 40 weekday sessions may require six to eight weeks of travel and scheduling. The breast-radiation trial demonstrated that many eligible patients declined treatment because of its intensity. (PubMed)
Transportation, work, caregiving, mobility, and cost should be discussed before therapy begins.
Coverage Requires a Documented Radiation Injury
The current Medicare National Coverage Determination includes:
- Osteoradionecrosis as an adjunct to conventional treatment
- Soft tissue radionecrosis as an adjunct to conventional treatment
Medicare does not cover HBOT simply because a patient previously received radiation. The medical record should establish a delayed tissue injury and explain how HBOT supports the broader treatment plan. (Centers for Medicare & Medicaid Services)
Useful documentation may include:
- Cancer diagnosis and treatment history
- Radiation site, dose, and dates
- Symptom timeline
- Cystoscopy, endoscopy, imaging, or operative findings
- Pathology or biopsy results
- Previous conventional treatment
- Evidence excluding recurrence when appropriate
- The specific clinical objective
- Planned surgery or reconstruction
- Serial response during treatment
Commercial payer policies may differ, and prior authorization may be required.
Coordinated Cancer Survivorship Care Is Essential
Delayed radiation injury often crosses specialty boundaries.
Depending on the affected tissue, care may involve:
- Radiation oncology
- Urology
- Gastroenterology
- Colorectal surgery
- Head and neck surgery
- Oral and maxillofacial surgery
- Plastic surgery
- Wound care
- Physical therapy
- Hyperbaric medicine
HBOT is most useful when these teams agree on the diagnosis and treatment endpoint.
For radiation cystitis, HBOT should complement urologic evaluation and bleeding management. For bowel injury, it should follow careful characterization of the cause of symptoms. For osteoradionecrosis, it should be coordinated with dental, surgical, and oncologic care. For reconstructive wounds, chamber treatment should be scheduled around debridement and flap or graft procedures.
HBOT and radiation injury recovery should therefore be understood as part of cancer survivorship medicine. The treatment may help selected tissues develop a more durable blood supply and greater capacity to heal, but it cannot reverse every structural consequence of radiation.
The strongest evidence currently supports careful, organ-specific patient selection, particularly for chronic radiation cystitis. Other applications may be appropriate, but their expected benefits and limitations should be discussed honestly.
