Conditions · evidence guide
Hyperbaric oxygen therapy and cancer: what the research actually shows
Hyperbaric oxygen therapy does not cause or promote cancer: three systematic reviews agree. It is FDA-cleared and UHMS-approved for one cancer-adjacent job, treating delayed radiation injury in survivors. It is not a proven cancer treatment, and using it against tumors remains investigational. Here is the evidence, study by study, with sources.
The short answer
Three things research supports, and one it does not
Most pages on this topic blend three very different questions into one answer. Separating them is the whole story: what HBOT is proven to do for cancer patients, what fear the evidence has retired, and what remains a research question.
Established: treating delayed radiation injury
HBOT is a UHMS-approved, FDA-cleared, and Medicare-covered treatment for delayed radiation injury (soft-tissue radiation necrosis and osteoradionecrosis), a complication of cancer radiotherapy. Supported by a randomized trial (RICH-ART, Lancet Oncology 2019) and a Cochrane review. This is the one established cancer-adjacent use.
Refuted fear: HBOT does not cause or promote cancer
The worry that oxygen could feed tumor growth has been examined directly. Three systematic reviews (Feldmeier 2003, Daruwalla 2006, Moen 2012) found no evidence that HBOT causes cancer, accelerates tumor growth, or increases recurrence, and a history of malignancy is not considered a contraindication.
Investigational: HBOT as an anti-tumor adjunct
Researchers are studying whether oxygenating tumors can make radiation or chemotherapy work better. The findings are preclinical and early clinical, and the FDA states plainly that HBOT is not proven to cure or treat cancer. Promising hypotheses are not treatments.
The distinction matters because the search results for this topic mix all three buckets freely. A clinic selling hope quotes the investigational bucket. A worried patient lands on the refuted fear. The established use, which genuinely helps survivors with radiation damage, gets lost between them. This page keeps them separate and grades each claim, starting with the fear most people arrive with. New to the therapy itself? Start with how hyperbaric oxygen therapy works.
The angiogenesis question
Does hyperbaric oxygen cause or promote cancer?
No, according to every systematic review that has examined the question directly. The concern was reasonable when it was raised, and it has been tested rather than assumed away.
Where the fear came from
The logic is easy to follow. HBOT drives oxygen into tissue and stimulates the growth of new blood vessels, which is exactly how it heals wounds. Tumors also need blood vessels to grow. Early clinical reports in the 1960s raised the worry that a therapy built to feed healing tissue might feed malignant tissue too, and the question has trailed the therapy ever since, as later reviews recount (Feldmeier 2003, Moen 2012).
What three systematic reviews concluded
The question has now been answered three times, independently. Feldmeier and colleagues reviewed the clinical and experimental literature in 2003 and found no evidence that HBOT has a cancer-causing or cancer-promoting effect (Undersea Hyperb Med, PMID 12841604). Daruwalla and Christophi repeated the exercise in 2006 with the same result (World J Surg, PMID 17102915). Moen and Stuhr extended it in 2012 across 28 studies and again found no tumor-growth stimulation and no increase in recurrence, with some tumor-inhibitory signals in specific models (Target Oncol, PMID 23054400).
Is HBOT safe if I have had cancer before?
On the evidence above, yes in the specific sense people usually mean: a history of malignancy is not considered a contraindication to hyperbaric oxygen therapy, and survivors are routinely treated in medical hyperbaric facilities for radiation injury. That is a statement about tumor stimulation, not a blanket clearance. The general safety profile still applies, drug interactions still matter, and anyone in active treatment should run the decision through their oncology team first, which the safety section below covers in detail.
The FDA position
Is HBOT a cancer treatment? No.
The FDA states it in plain language for consumers: hyperbaric oxygen therapy has not been clinically proven to cure or be effective in the treatment of cancer.
The FDA's consumer guidance on hyperbaric oxygen therapy warns directly against claims that HBOT can cure or treat cancer, and no HBOT device carries a cancer-treatment indication. The cleared indications sit elsewhere: wounds, infections, decompression illness, radiation injury, and a short list of acute emergencies, set out in our guide to FDA-cleared indications. When a clinic markets sessions as a cancer therapy, it has stepped outside both the evidence and the regulatory position.
Does oxygen kill cancer cells?
Not directly, in humans, in any way the evidence currently supports. The research hypothesis is subtler: tumors often outgrow their blood supply and become hypoxic, and hypoxic tumor cells resist radiation and some chemotherapy. Oxygenating the tumor might remove that shield. That is a sensitization hypothesis, explored below, not a claim that oxygen is poisonous to cancer.
What about studies showing tumors shrank in animals?
They exist, and they are why the research continues. Moen and Stuhr's review catalogued tumor-inhibitory signals in specific animal and cell models, breast and glioma among them, alongside neutral results in others (PMID 23054400). Animal responses do not transfer to patients on their own: no adequately powered human trial has tested HBOT as an anti-tumor therapy, and none of the reviews above concluded otherwise. Preclinical promise is the start of a research question, not the end of one.
Bucket A, the proven one
HBOT for radiation side effects: the established use
Radiotherapy saves lives and sometimes damages the tissue it passes through, months or years later. Treating that damage is HBOT's one established cancer-adjacent role, recognized by the UHMS, the FDA, and Medicare.
Delayed radiation injury (soft-tissue radiation necrosis and osteoradionecrosis) is a UHMS-approved indication and is covered by Medicare under National Coverage Determination 20.29. The mechanism is the therapy's home turf: irradiated tissue loses its blood supply over time, and HBOT drives angiogenesis and oxygen delivery back into exactly that tissue. Our radiation injury evidence guide walks the full mechanism and literature; the three headline applications follow.
Radiation cystitis
Chronic radiation-induced cystitis affects roughly 5 to 10% of patients after pelvic radiotherapy, with bleeding, urgency, and pain that can persist for years. The strongest HBOT trial in any cancer-adjacent indication addressed it: RICH-ART, a randomized phase 2-3 trial across five Nordic university hospitals, randomized 87 patients to HBOT (30-40 sessions of 100% oxygen at 2.4-2.5 ATA, 80-90 minutes daily) versus standard care, and found a significant improvement in patient-reported urinary symptoms (Lancet Oncol 2019, PMID 31537473). The five-year follow-up reports that symptom relief persisted in treated patients (EClinicalMedicine 2025, PMID 40291346).
Radiation proctitis
Rectal injury after pelvic radiation presents similarly: bleeding and urgency caused by a poorly perfused, fibrotic rectal wall. The randomized evidence is thinner than for cystitis, and the 2023 Cochrane review groups rectal injury with the other late radiation injuries as low- to moderate-certainty evidence of benefit (CD005005, PMID 37585677). It remains a covered, guideline-supported use, with honest uncertainty about which patients benefit most.
Osteoradionecrosis and dental work after head and neck radiation
Bone exposed to high-dose radiation, classically the mandible after head and neck cancer treatment, can lose its ability to heal, and dental extraction in that bone was long managed with prophylactic HBOT under the Marx protocol. The picture is more nuanced than the tradition suggests: the HOPON randomized trial found the observed osteoradionecrosis rate low enough that routine prophylactic HBOT before dental surgery in irradiated mandibles was unnecessary, explicitly challenging the old standard (Int J Radiat Oncol Biol Phys 2019, PMID 30851351). Established ORN remains a covered indication; blanket prevention before every extraction is where the evidence has moved on.
Does insurance or Medicare cover HBOT for radiation injury?
Yes. Soft-tissue radiation necrosis and osteoradionecrosis sit on Medicare's covered list in NCD 20.29, and commercial policies generally follow. Coverage attaches to the documented indication and a physician's order, delivered in a medical facility, not to the diagnosis of cancer itself. The mechanics (authorization, session caps, what a course pays) are in our insurance coverage guide.
The citations
The evidence, study by study
Every load-bearing claim on this page, mapped to the study behind it. Preclinical rows are labeled as such: animal and cell findings are research signals, not patient evidence.
| Study | Journal | Design | What it found | Level |
|---|---|---|---|---|
| Feldmeier et al. 2003 | Undersea Hyperb Med | Systematic review | No evidence HBOT promotes tumor growth or recurrence; a history of malignancy is not a contraindication | Systematic review |
| Daruwalla & Christophi 2006 | World J Surg | Systematic review | Independently reached the same conclusion across the published tumor literature | Systematic review |
| Moen & Stuhr 2012 | Target Oncol | Review of 28 studies | No tumor-growth stimulation or recurrence enhancement; tumor-inhibitory signals in some models | Review (28 studies) |
| Lin, Bennett et al. 2023 | Cochrane (CD005005) | Cochrane review | HBOT may improve outcomes in late radiation tissue injury of the head, neck, bladder, and rectum (low- to moderate-certainty evidence) | Cochrane review |
| Oscarsson et al. 2019 (RICH-ART) | Lancet Oncol | Randomized phase 2-3, 87 patients, 5 Nordic hospitals | 30-40 sessions at 2.4-2.5 ATA significantly improved urinary symptoms of late radiation cystitis vs standard care | RCT |
| Oscarsson et al. 2025 (RICH-ART follow-up) | EClinicalMedicine | Five-year RCT follow-up | Reports long-term symptom relief in patients treated with HBOT for chronic radiation cystitis | RCT follow-up |
| Bennett et al. 2018 | Cochrane (CD005007) | Cochrane review | Some evidence of improved local tumor control when HBOT accompanies radiation in head and neck tumors, tied to unusual fractionation schemes; interpret with caution | Cochrane review |
| HOPON 2019 | Int J Radiat Oncol Biol Phys | Randomized controlled trial | Prophylactic HBOT before dental surgery in irradiated mandibles was unnecessary at the low observed osteoradionecrosis rate, challenging a long-standing protocol | RCT |
| Chong et al. 2004 | BJU Int | Animal study (in vivo) | HBOT did not accelerate latent prostate cancer, relevant when treating radiation cystitis in prostate cancer survivors | Preclinical |
PMIDs, in row order: 12841604, 17102915, 23054400, 37585677, 31537473, 40291346, 29637538, 30851351, 15610104. Each links to its PubMed record from the sources card. The pattern across the table: strong and consistent on the cancer-promotion question and on radiation injury, early and cautious on everything investigational.
Bucket C, the frontier
HBOT alongside chemotherapy and radiation: what is being researched
The investigational bucket is real research, not marketing copy. It also is not a treatment anyone can offer you today. Here is the hypothesis, the evidence so far, and the safety notes that come with it.
Tumor hypoxia in plain language
Fast-growing tumors outstrip their blood supply, and their cores become hypoxic. Hypoxic cells are harder to kill: radiation damages DNA largely through oxygen-dependent chemistry, and several chemotherapy agents work worse in low-oxygen tissue. The hypothesis behind this whole research line is that flooding the tumor with oxygen before treatment could remove that protection, an idea traced through the radiobiology literature and summarized in Moen and Stuhr 2012.
HBOT as a radiosensitizer: what trials found
A 2018 Cochrane review gathered the trials of HBOT given with radiotherapy and found some evidence of improved local tumor control in head and neck cancers, with two heavy caveats: the positive results clustered in trials using unusual radiation fractionation schemes, and some older protocols that delivered HBO and irradiation together produced severe tissue injury. The reviewers' conclusion was caution, not adoption (CD005007, PMID 29637538).
HBOT with chemotherapy: small studies, open questions
The chemotherapy side is earlier still: small studies and preclinical work, mixed results, no powered randomized trial of HBOT as a chemo adjuvant. Two safety notes from the literature matter more than the efficacy signals at this stage, both cited through Moen and Stuhr 2012. Certain agents, including bleomycin, doxorubicin, cisplatin, disulfiram, and mafenide acetate, carry cautions or contraindications with HBOT. And timing is not a detail: protocols where irradiation coincided with, rather than followed, HBO exposure caused serious tissue injury in older series.
Can HBOT make chemotherapy or radiation work better?
Possibly, in specific settings, and that is precisely as far as the evidence goes. The honest summary of the investigational bucket: a coherent biological rationale, encouraging preclinical signals, one cautious Cochrane signal in head and neck radiotherapy, and no adequately powered trial that would let anyone offer this as a treatment. Decisions inside active cancer therapy belong to the oncology team.
For wellness operators
What you can say, and what you must not claim
If clients ask your studio about cancer, and they will, the compliant answers are short. The FDA has drawn the line explicitly, and staying inside it protects the client and the business.
| You can say | You must not claim | |
|---|---|---|
| Talking about the evidence | HBOT is FDA-cleared and UHMS-approved for delayed radiation injury, a complication of radiotherapy | That HBOT treats, cures, or prevents cancer. The FDA explicitly warns against this claim |
| Talking about safety | Three systematic reviews found no evidence that HBOT causes or promotes cancer | That HBOT is proven safe for every individual situation. Active cancer care decisions belong to the oncology team |
| A client in active treatment asks to book | Ask them to clear it with their oncologist first, and accept that answer | Positioning your sessions as part of their cancer treatment or recovery protocol |
| A survivor asks about radiation injury | Point them to a UHMS-accredited medical hyperbaric facility and their physician | Offering wellness sessions as a substitute for prescribed medical HBOT |
Two scripts cover most conversations. "I have cancer, will this help?" gets: HBOT is not a cancer treatment, the FDA is explicit about that, and anything during active treatment needs your oncologist's sign-off first. "I had cancer, is this safe?" gets: the research has specifically looked for tumor promotion and not found it, and if you are dealing with radiation damage, that is a medical indication handled by accredited clinical facilities, which your physician can refer you to. When the question is medical, the answer is a referral.
Honest edges
Limitations and open questions
The evidence is strong where it is strong and thin where it is thin. Both halves deserve the same clarity.
The cancer-promotion question is the most settled: three independent systematic reviews across decades of literature is about as convergent as this field gets. The radiation-injury use rests on a genuinely randomized trial and a Cochrane review, though Cochrane itself grades the certainty low to moderate and asks for better patient selection. Even there, the HOPON result shows the literature correcting itself in public: an entrenched prevention protocol was tested and found unnecessary.
The open questions sit in the investigational bucket. Results differ across tumor models (inhibitory signals in breast and glioma models, neutral results in prostate and colorectal models). The positive radiosensitization trials used fractionation schemes modern centers do not. HBOT protocols vary widely across studies, which makes them hard to pool. Survival and recurrence endpoints are largely unstudied, and no adequately powered randomized trial has tested HBOT as an anti-tumor therapy. The research is worth watching; none of it is a reason to sell or buy a cancer claim today.
Before any session
Safety, contraindications, and when to call your oncologist first
The cancer-specific reassurance does not suspend the general rules. HBOT has a real safety profile, and some of it interacts directly with cancer treatment.
The common side effects are mundane: ear barotrauma on compression is the most frequent, and temporary changes in visual acuity can appear across a long course, both noted in the Cochrane review's adverse-event summary. Serious complications are rare in screened patients. The one absolute contraindication is an untreated pneumothorax. Our chamber safety guide and the side effects and contraindications guide carry the full clinical picture.
The cancer-specific cautions come on top. Several chemotherapy agents, including bleomycin, doxorubicin, cisplatin, disulfiram, and mafenide acetate, are flagged in the literature for caution or contraindication with HBOT (cited through Moen and Stuhr 2012). Timing around radiotherapy matters, as the older combined-exposure protocols showed. And the rule that overrides all of it: anyone in active cancer treatment, or considering HBOT for anything cancer-related, should make that decision with their oncology team. A chamber operator, us included, is not a substitute for that conversation.
FAQ
Cancer and HBOT questions
Does hyperbaric oxygen therapy cause cancer?
No evidence says it does. The concern that oxygen could feed tumor growth has been examined directly in three systematic reviews: Feldmeier et al. (Undersea Hyperb Med, 2003), Daruwalla and Christophi (World J Surg, 2006), and Moen and Stuhr (Target Oncol, 2012), which together covered decades of clinical and experimental literature. None found evidence that HBOT causes cancer, accelerates tumor growth, or increases recurrence, and a history of malignancy is not considered a contraindication to hyperbaric treatment.
Can hyperbaric chambers treat cancer?
No. Hyperbaric oxygen therapy is not a proven cancer treatment, and the FDA states that HBOT has not been clinically proven to cure or be effective in the treatment of cancer. Research into HBOT as an adjunct that could make radiation or chemotherapy work better is ongoing, but it is preclinical and early clinical work. Any clinic marketing HBOT as a cancer cure is making a claim the evidence does not support, and the FDA specifically warns consumers about this.
Is hyperbaric oxygen therapy safe for cancer patients?
For most people with a current or past cancer diagnosis, the systematic-review evidence is reassuring: HBOT does not appear to stimulate tumors. The general HBOT safety profile still applies (ear barotrauma is the most common side effect, temporary vision changes are possible, and untreated pneumothorax is an absolute contraindication), and some chemotherapy agents interact with HBOT, so timing and drug-specific cautions matter. The decision belongs with your oncology team, not with a chamber operator.
Does HBOT help with radiation therapy side effects?
Yes, this is the established use. Delayed radiation injury, including radiation cystitis, radiation proctitis, soft-tissue necrosis, and osteoradionecrosis, is a UHMS-approved and Medicare-covered HBOT indication. The strongest trial is RICH-ART (Lancet Oncology, 2019), a randomized phase 2-3 study across five Nordic hospitals in which 30 to 40 HBOT sessions significantly improved the urinary symptoms of late radiation cystitis, with long-term relief reported at five-year follow-up. A 2023 Cochrane review rates the evidence as low- to moderate-certainty and calls for careful patient selection.
Can HBOT cause cancer to come back?
The reviews that looked for exactly this found no signal. Feldmeier 2003 examined recurrence specifically and found no increase, and Moen and Stuhr's 2012 review of 28 studies reported no recurrence enhancement. One animal study (Chong et al., BJU Int, 2004) tested latent prostate cancer directly and found HBOT did not accelerate it, which matters because prostate cancer survivors are a major group treated for radiation cystitis.
How many HBOT sessions are needed for radiation injury?
The RICH-ART trial protocol is the reference point: 30 to 40 sessions, breathing 100% oxygen at 240 to 250 kPa (2.4 to 2.5 ATA) for 80 to 90 minutes daily. Real-world courses for delayed radiation injury typically run in that 30 to 40 session range at clinical pressures, set by the treating facility's protocol and the tissue being treated. These are medical courses delivered in accredited facilities, not wellness sessions.
Will insurance cover HBOT if I have had cancer?
Coverage follows the indication, not your cancer history. Medicare's National Coverage Determination 20.29 covers HBOT for soft-tissue radiation necrosis and osteoradionecrosis, and most commercial policies mirror that. A history of cancer neither qualifies you nor disqualifies you on its own: what matters is a documented covered diagnosis, such as delayed radiation injury, ordered by a physician. Our insurance coverage guide explains how payers make these decisions.
Who should not use hyperbaric oxygen therapy?
The one absolute contraindication is an untreated pneumothorax. Relative cautions include certain chemotherapy agents (bleomycin, doxorubicin, cisplatin, disulfiram, and mafenide acetate are named in the literature, cited through Moen and Stuhr 2012), recent ear surgery, severe claustrophobia, and some lung conditions. Anyone in active cancer treatment should involve their oncologist before booking any session. Our safety pillar and the side effects and contraindications guide carry the full picture.
Last updated: August 2026. This guide is educational and is not medical advice. It summarizes published research and regulatory positions, which evolve. Decisions about cancer treatment, and about hyperbaric oxygen therapy alongside it, belong with your oncology team and treating physicians.