TL;DR: The 2024-2026 evidence base positions hyperbaric oxygen therapy as a meaningful adjunct in oncology care, not as a primary cancer treatment. Recent systematic reviews and pilot trials show measurable benefit for radiation necrosis, mandibular osteoradionecrosis, and compromised post-surgical tissue in cancer survivors. Mechanistic research is also investigating how HBOT may reoxygenate hypoxic tumour regions and enhance the effect of radiotherapy, chemotherapy, and immunotherapy. The clinical adjunct role is established. The direct anti-tumour role remains investigational and demands larger Canadian trials.
Hyperbaric oxygen therapy (HBOT) is a medical treatment in which a patient breathes 100% oxygen inside a pressurised chamber, typically at 2.0 to 2.4 atmospheres absolute. In oncology, HBOT is not used to kill cancer cells. It is used to repair tissue damaged by radiation, support healing after cancer surgery, and is being studied as a way to overcome tumour hypoxia, a known driver of treatment resistance. This evidence review summarises the 2024-2026 research landscape for hyperbaric oxygen in cancer care, focusing on what the literature now supports and where the research gaps remain. Canada Hyperbarics maintains a database of more than 14,000 indexed HBOT studies, and the trends below reflect a clear shift in how oncology researchers are framing hyperbaric oxygen.
Why is tumour hypoxia a research target for hyperbaric oxygen?
Tumour hypoxia is a state of low intratumoral oxygen caused by abnormal vasculature and rapid cancer cell growth. It is one of the strongest predictors of treatment failure across solid tumours. A 2025 mechanistic review in Biomedicine and Pharmacotherapy by Meng and colleagues argued that hypoxia drives resistance to chemotherapy, radiotherapy, and immune checkpoint inhibitors by reprogramming tumour metabolism, supporting angiogenesis, and enabling immune evasion. The review proposed that hyperbaric oxygen therapy, by dramatically raising dissolved plasma oxygen, can briefly reoxygenate hypoxic regions and remodel the tumour microenvironment. Reported mechanistic effects include enhanced drug penetration, augmented radiation-induced DNA damage, and reduced hypoxia-driven immunosuppression. The authors flag controversies around dose, timing, and rare reports of pro-angiogenic effects, but conclude that integrating HBOT into multimodal regimens warrants serious investigation.
A separate 2025 review in Medical Gas Research looking specifically at oxygen’s role in breast cancer reached a similar conclusion. The authors framed hyperbaric oxygen as one of several emerging strategies, alongside oxygen-generating nanoparticles and oncolytic viral platforms, that may relieve intratumoral hypoxia and improve response to traditional anti-cancer therapies. For now, this remains hypothesis-driven research. No phase III randomised controlled trial has yet shown that HBOT improves overall survival in any solid tumour. The mechanistic case is strong. The clinical confirmation is pending.
What does the 2024-2026 evidence show for radiation injury after cancer treatment?
Radiation injury is where the modern evidence base is strongest and most clinically actionable. Late tissue radiation injury affects a meaningful share of cancer survivors, and hyperbaric oxygen has been a Health Canada recognised indication for soft tissue radiation injury and osteoradionecrosis for years. The 2024-2026 literature has refined, rather than overturned, this role.
For brain radiation necrosis after stereotactic radiosurgery, a 2023 systematic review and consensus statement from the International Stereotactic Radiosurgery Society pooled outcomes across bevacizumab, laser interstitial thermal therapy, surgical resection, and HBOT. Bevacizumab dominated the evidence base with pooled symptom improvement or stability of 86% across 13 reports. HBOT was supported by fewer studies but remained in the recommended toolkit, particularly for patients who cannot tolerate bevacizumab or corticosteroids. A 2024 paediatric case report in the Journal of Neurosurgery Case Lessons documented successful HBOT treatment of cerebral radiation necrosis in a 5-year-old with previous complications from steroid therapy, an instructive illustration of HBOT’s role when first-line options fail.
For mandibular osteoradionecrosis (MORN), the picture is more nuanced. A 2024 review in Otolaryngology Head and Neck Surgery by Fritz and colleagues described a paradigm shift away from routine prophylactic HBOT before dental extractions in irradiated patients. Growing evidence supports pentoxifylline and tocopherol regimens in early-stage disease, with HBOT reserved for moderate-to-late stage or surgical-adjunct use. A complementary 2025 review in Current Opinion in Otolaryngology and Head and Neck Surgery by Kahng and colleagues reached parallel conclusions for the broader category of radiation-associated head and neck wounds, compromised grafts and flaps, and necrotizing soft tissue infections. Most evidence remains retrospective, but the adjunctive role is supported. Typical protocols sit at 2.0 to 2.4 atmospheres absolute for 90 minutes, often across 30 daily sessions.
Does HBOT help radiation-induced dermatitis in breast cancer?
A 2025 randomised pilot study in Supportive Care in Cancer by Lee and colleagues randomised 30 breast cancer patients receiving adjuvant radiotherapy to either HBOT at 1.5 atmospheres absolute, three sessions per week for seven weeks, or standard care. The primary endpoint was the rate of grade 2 or higher radiation-induced dermatitis. Both groups landed at 73.3%, with no statistically significant difference. Secondary patient-reported outcomes showed non-significant trends favouring HBOT. HBOT was well tolerated with no serious adverse events.
The pilot result should not be read as a negative finding. The sample was small, the pressure protocol was relatively mild, and dermatitis grading is not the most sensitive outcome for HBOT, which has historically been studied for late rather than acute radiation effects. The trial sets up a larger randomised trial with optimised protocols. For Canadian researchers, this is a productive design question: do longer dose, higher pressure, or delayed onset protocols change the result?
What is the evidence for HBOT in cancer treatment-related xerostomia?
Cancer treatment-related xerostomia, or chronic dry mouth, affects most head and neck radiotherapy patients and has no definitive treatment. A 2024 narrative review in the European Journal of Medical Research by Hosseini and colleagues catalogued the available interventions, including salivary substitutes, muscarinic agonists, photobiomodulation, acupuncture, and hyperbaric oxygen therapy. The authors flagged HBOT as one of several emerging adjuncts but emphasised that evidence on efficacy, safety, and optimal protocol remains limited and contested. No HBOT-specific recommendation can be drawn from the current data. This is a clear research gap that would benefit from a Canadian multi-centre trial.
How does the 2024-2026 evidence compare across cancer-related HBOT indications?
| Indication | Evidence Quality | Primary Source | Clinical Status |
|---|---|---|---|
| Soft tissue radiation injury | Moderate (multiple retrospective, small RCTs) | Kahng 2025; UHMS guidance | Established adjunct |
| Osteoradionecrosis of the mandible | Moderate, role refined | Fritz 2024 | Adjunct in moderate-to-late stage |
| Brain radiation necrosis | Low to moderate | Vellayappan 2023 ISRS | Second-line option |
| Compromised grafts and flaps | Moderate retrospective | Kahng 2025 | Established adjunct |
| Radiation-induced dermatitis | Pilot RCT, no benefit yet | Lee 2025 | Investigational |
| Cancer treatment-related xerostomia | Limited, contested | Hosseini 2024 | Investigational |
| Direct anti-tumour effect via reoxygenation | Mechanistic, preclinical | Meng 2025 | Hypothesis-stage research |
What are the open research questions for Canadian investigators?
The 2024-2026 literature surfaces five priority research questions that align with Canadian clinical and infrastructure strengths.
- Optimal pressure and dose for radiation injury prevention. Most protocols cluster at 2.0 to 2.4 ATA for 30 sessions, but the dose-response relationship has never been systematically tested in a large randomised setting.
- Patient selection for brain radiation necrosis HBOT. Bevacizumab is the default for symptomatic disease, but a subgroup of patients cannot tolerate it. Predictive biomarkers for HBOT response would help triage these patients.
- HBOT timing relative to radiotherapy. Mechanistic evidence supports concurrent reoxygenation, but logistics and safety remain barriers. A pragmatic Canadian trial could compare pre-radiation, concurrent, and post-radiation HBOT.
- Dermatitis and xerostomia protocols. Pilot data are inconclusive. A multi-centre Canadian trial at 2.4 ATA, started prophylactically, would provide higher-quality evidence than the published pilots.
- Long-term safety of HBOT in cancer survivors. Concerns about pro-angiogenic effects in residual tumour are theoretical but not resolved. Canadian registries are well positioned to track long-term oncologic outcomes.
Where can Canadian researchers access HBOT capacity for trials?
Canada has a moderately distributed HBOT infrastructure, with hospital-based chambers in most provinces and a growing network of private and accredited clinics. Hospital chambers tend to be multiplace and prioritise emergency and inpatient cases such as decompression sickness, carbon monoxide poisoning, and acute crush injuries. Private and regulated outpatient facilities often have monoplace capacity that can be scheduled for protocol-driven elective treatment. Researchers planning oncology adjunct trials should consult our directory of hospitals and regulated facilities when scoping site capacity. The Canadian Undersea and Hyperbaric Medical Association (CUHMA) and the Undersea and Hyperbaric Medical Society maintain indication guidance that Canadian ethics boards expect to see referenced in protocols. Canada Hyperbarics provides a continually updated research database that researchers can use to scan the global HBOT evidence base by condition.
How should referring oncologists currently think about HBOT?
For cancer survivors with established late radiation injury, osteoradionecrosis, compromised post-surgical grafts, or refractory radiation necrosis, the 2024-2026 evidence continues to support HBOT as a Health Canada recognised adjunct. Referral pathways differ by province. Many provincial cancer programmes will fund hospital-based HBOT for recognised indications when an oncologist or surgeon requests it. For experimental or non-approved oncology applications, treatment generally falls outside provincial coverage and would require research ethics approval. Patients and clinicians can read a plain-language overview of HBOT for radiation injury for non-research context. Canada Hyperbarics has covered provincial coverage rules for HBOT in detail elsewhere on the site.
Frequently asked questions
Is hyperbaric oxygen therapy approved as a cancer treatment in Canada?
No. Hyperbaric oxygen therapy is not approved by Health Canada as a treatment for cancer itself. It is recognised as an adjunct for managing radiation tissue injury, osteoradionecrosis, and other complications of cancer treatment. Direct anti-tumour use remains investigational and is restricted to clinical research.
Can HBOT help cancer cells grow?
This is a long-standing concern in oncology. The 2025 mechanistic review by Meng and colleagues acknowledged theoretical pro-angiogenic effects under certain conditions but concluded that the overall preclinical and clinical evidence does not support a net pro-tumour effect at standard HBOT protocols. Multiple cohort studies of cancer survivors treated for radiation injury have not shown increased recurrence rates. The question is not fully resolved and continues to inform safety monitoring in active trials.
What is the typical HBOT protocol used in radiation injury trials?
Most published protocols use 100% oxygen at 2.0 to 2.4 atmospheres absolute for 90 minutes, delivered as 20 to 40 daily sessions, five days per week. The Lee 2025 breast cancer dermatitis pilot used a lower pressure protocol at 1.5 atmospheres absolute, which may partly explain the negative result. Researchers designing new Canadian trials usually default to the 2.0 to 2.4 ATA range unless there is a specific physiological reason to deviate.
Are there active Canadian HBOT cancer trials?
Activity is modest but increasing. Researchers should check the Canadian Institutes of Health Research project database and Health Canada’s clinical trials database for current listings. The 2024-2026 international evidence is creating new opportunities for Canadian investigators to design trials in radiation dermatitis, xerostomia, and post-surgical wound healing.
Is HBOT safe for patients with active cancer?
The safety record across the 2024-2026 reviews is reassuring. The Lee 2025 pilot reported no serious adverse events. Standard contraindications still apply, including untreated pneumothorax and certain chemotherapeutic agents that interact with oxygen exposure. Patient screening protocols handle these issues effectively. Active cancer alone is not a contraindication for HBOT used to manage radiation injury.
What is the difference between adjunctive HBOT and direct anti-tumour HBOT?
Adjunctive HBOT supports tissue healing and manages side effects of cancer treatment, such as radiation injury and compromised wound healing. Direct anti-tumour HBOT is a research concept in which oxygen is used to reoxygenate hypoxic tumour regions and improve the cytotoxic effect of radiotherapy or chemotherapy. The first is supported by clinical evidence. The second is supported by mechanistic and preclinical evidence and remains investigational.
Where can researchers find the underlying studies?
Every study referenced in this article is indexed in the Canada Hyperbarics research database with a plain-language summary and a link to the original PubMed record. Researchers can browse the full database at the research bank, or access referenced studies directly using the citation list below.
Cited literature
- Meng Y, Zhou L, Xia Y, et al. Breaking the hypoxia barrier: advances and challenges of hyperbaric oxygen therapy in cancer treatment (PubMed). Biomed Pharmacother. 2025;193:118703.
- Lee JY, Hyun MH, Yang G, Lee S. Efficacy and safety of hyperbaric oxygen therapy for radiation-induced dermatitis in patients with breast cancer: a randomized pilot study (PubMed). Support Care Cancer. 2025;33(5):399.
- Vellayappan B, Lim-Fat MJ, Kotecha R, et al. A Systematic Review Informing the Management of Symptomatic Brain Radiation Necrosis After Stereotactic Radiosurgery and ISRS Recommendations (PubMed). Int J Radiat Oncol Biol Phys. 2023;118(1):14-28.
- Hosseini MS, Sanaie S, Mahmoodpoor A, et al. Cancer treatment-related xerostomia: basics, therapeutics, and future perspectives (PubMed). Eur J Med Res. 2024;29(1):571.
- Fritz MA, Arianpour K, Liu SW, et al. Managing Mandibular Osteoradionecrosis (PubMed). Otolaryngol Head Neck Surg. 2024;172(2):406-418.
- Jimenez MJD, Mohiuddin M, Li D, Ruge JR. Treatment of cerebral radiation necrosis using hyperbaric oxygen therapy in a child: illustrative case (PubMed). J Neurosurg Case Lessons. 2024;8(21).
- Kahng PW, Derakhshan A, Gadkaree SK. Hyperbaric oxygen therapy for wounds of the face, head and neck (PubMed). Curr Opin Otolaryngol Head Neck Surg. 2025;33(4):222-229.
- Darie CC, Hukovic A, Maynard VD, Neagu AN. Roles of oxygen in the tumorigenesis, progression, and treatment of breast cancer (PubMed). Med Gas Res. 2025;16(1):41-45.
Medical disclaimer: This content is for informational purposes only and does not constitute medical advice. Hyperbaric oxygen therapy as a cancer treatment is not approved by Health Canada. Approved adjunctive indications such as radiation tissue injury and osteoradionecrosis are clinically supported. Researchers and clinicians should consult Health Canada, the Canadian Undersea and Hyperbaric Medical Association, and current institutional guidelines before designing protocols or making referral decisions.