HBOT and cancer: two questions that need different answers

“HBOT and cancer” often combines two separate questions. Keeping them separate is essential.

HBOT is not a cancer treatment

HBOT Medics does not offer hyperbaric oxygen therapy to treat, shrink or cure cancer. Research into oxygen, tumour biology and radiotherapy does not turn a private chamber course into cancer treatment.

If you are undergoing cancer treatment, decisions about additional therapies should stay with your oncology team.

Why does the question come up at all?

Cancer and oxygen appear together in a lot of online material, and some of it is misleading. Two real things sit underneath the confusion.

First, radiotherapy works partly through oxygen-dependent effects on cells, which is why oxygen has been studied alongside radiotherapy in hospital research. That is specialist oncology research, not a reason to buy chamber sessions.

Second, radiotherapy can injure normal tissue months or years later, and hyperbaric oxygen is used by specialist services for some of those injuries. That second question is where most of the useful evidence sits, and it is the rest of this article.

The advertising rules are clear on the first point. A clinic may not claim its therapy treats cancer without clinical trial evidence, and none supports that claim for a private chamber.

Late radiation tissue injury is different

Radiotherapy can sometimes leave lasting injury in normal tissue months or years after treatment. This may affect bone or soft tissue in areas such as the head and neck, bladder or lower bowel.

A 2023 Cochrane review found that HBOT may improve outcomes for selected late radiation tissue injuries. It also stressed that the studies were generally small, certainty ranged from low to moderate, and the best patient selection, timing and oxygen dose remain uncertain.

The Undersea and Hyperbaric Medical Society lists delayed radiation injury involving soft tissue or bone among its accepted indications.

What have the major trials found?

The individual trials show why the overall picture is described as mixed rather than settled.

• Jaw bone injury after dental surgery. The UK HOPON trial randomised people who needed extractions or implants in a jaw that had received high-dose radiotherapy. Adding 30 sessions of oxygen at 2.4 ATA did not reduce the rate of osteoradionecrosis. A 2024 international guideline from ISOO, MASCC and ASCO concluded that HBOT for preventing and managing osteoradionecrosis remains largely unjustified.
• Bowel symptoms after pelvic radiotherapy. The UK HOT2 trial gave 84 people 40 sessions at 2.4 ATA or a sham procedure. At 12 months there was no significant difference in bowel symptoms or rectal bleeding.
• Bladder symptoms after radiotherapy. The Nordic RICH-ART trial randomised 87 people with radiation cystitis to 30 to 40 sessions at about 2.4 to 2.5 ATA or standard care. Urinary symptom scores improved more with HBOT, but the trial was not blinded, and 41% of the treated group had temporary side effects affecting sight or hearing.

The same Cochrane review recorded harms as well as benefits, including a higher risk of temporarily reduced visual sharpness and ear barotrauma.

Our pressure is an important limit

Our chamber operates at 1.5 ATA, as described in what HBOT is. Much of the late-radiation-injury evidence comes from higher-pressure medical protocols. Results from those protocols cannot simply be assumed to apply to this service.

For suspected osteoradionecrosis, radiation cystitis, radiation proctitis or another serious late radiation injury, speak with your oncology or surgical team about an appropriate specialist pathway.

Is it available on the NHS?

In England, NHS England routinely commissions hyperbaric oxygen for decompression illness and gas embolism. It lists radiation damage after pelvic radiotherapy among the uses it does not routinely commission. Where hyperbaric treatment for a radiation injury is considered, that decision is made by specialist teams, and access varies.

Why is the evidence so hard to settle?

Several features of this research make a clear verdict difficult, and they are worth knowing before you read any claim about it.

• Small trials. Many studies enrolled a few dozen people. Small trials can miss real effects and can also exaggerate them.
• Blinding is difficult. A convincing sham chamber is hard to build, so some trials compared HBOT with standard care alone. People who know they are receiving an intensive treatment may report symptoms differently.
• Different injuries behave differently. Jaw bone, bowel and bladder injuries are not one condition. A result in one tissue does not transfer automatically to another.
• Different doses. Trials varied in pressure, session length and the number of sessions, which makes pooling them less precise.
• Commitment. Specialist protocols usually mean daily hospital visits for several weeks, which is a real burden for someone already recovering from cancer treatment.

This is why the Cochrane reviewers called for better information on which people may respond and on the best timing and dose, rather than a blanket recommendation.

What to ask your cancer team

If late effects of radiotherapy are affecting you, these questions usually lead somewhere useful:

1. Which part of my symptoms could be a late effect, and what else needs ruling out?
2. What are the standard treatments for this injury, and what is the evidence for each?
3. Is a specialist hyperbaric referral relevant for my situation, and what pressure and number of sessions would that involve?
4. Who should I contact if symptoms change or get worse?

Our explainer on what hyperbaric oxygen therapy is covers the underlying mechanism and its limits, and who HBOT is not suitable for explains the screening questions, including recent cancer treatment.