Can Hyperbaric Oxygen Improve Cancer Treatment Effectiveness?
Writing in Frontiers in Oncology in 2025, a group from Dalian Medical University reviewed the mechanisms, clinical translation outcomes, and safety issues of pairing hyperbaric oxygen therapy with biomedical engineering tools. Across the studies they collected, hyperbaric oxygen raised nanodrug penetration depth by 1.8 times and immune cell infiltration by 2.3 times, and lifted tumor oxygen partial pressure from roughly 5 mmHg to 30-50 mmHg.
Tumors build low-oxygen (hypoxic) environments that blunt treatment. Hypoxia strengthens tumor cell resistance to chemotherapy drugs, suppresses the reactive oxygen species that chemotherapy relies on, shifts expression of resistance-related genes and proteins, and obstructs drug delivery. It also makes tumors more invasive, drives new blood vessel formation, and accelerates malignant progression and metastasis. Hyperbaric oxygen therapy delivers 100% oxygen at pressure above sea level atmospheric pressure, and that raises oxygen partial pressure inside tumor tissue.
What the Data Show
Tumor Microenvironment Changes:
- Oxygen levels: Tumor pO2 rises from about 5 mmHg to 30-50 mmHg
- Hypoxic drug resistance: Resistance to chemotherapy drugs such as cisplatin increases 2-3 times under hypoxia
- Mechanism of that resistance: Hypoxia-inducible factor (HIF-1alpha) activation upregulates drug metabolism genes including ABCB1 and SLC22A1, promoting drug efflux and metabolism
- Extracellular matrix: Hyperbaric oxygen induces reactive oxygen species and regulates matrix metalloproteinase (MMP) expression, degrading collagen and fibronectin
- Tumor stiffness: Reduced
Treatment Enhancement:
- Nanodrug penetration depth: Increases 1.8 times
- Immune cell infiltration rate: Increases 2.3 times
- Chemotherapy, radiotherapy, and immunotherapy: Sensitivity improves as hypoxia is relieved
Dr. Kumar’s Take
The logic here is mechanical, and that is why I find it interesting. A tumor is not just a mass of malignant cells. It is a mass wrapped in a dense, stiff protein scaffold with a starved oxygen supply, and both of those features work against every drug you push toward it. Adding oxygen under pressure attacks both at once: it relieves the hypoxia that drives resistance, and it triggers matrix breakdown that softens the barrier.
Nearly doubling how deep a drug travels into a tumor, and more than doubling how many immune cells get inside, are the kind of delivery numbers that matter more than another incremental drug tweak. If the payload never reaches the tumor core, its potency in a dish is irrelevant.
The caution I would give any patient is that this is a review of mechanisms and early translation, not a report of a completed trial. The authors themselves point to what still needs work: individualized treatment plans, long-term efficacy evaluation, and deeper molecular mechanism analysis. None of these combinations is standard oncology care today.
How HBOT Transforms the Tumor Microenvironment
Breaking Down the Protective Matrix: Hyperbaric oxygen induces reactive oxygen species generation, which degrades collagen and fibronectin in the tumor’s extracellular matrix. That matrix is a physical barrier around the tumor. As it breaks down, tumor stiffness falls, nanodrug penetration depth increases 1.8 times, and the immune cell infiltration rate increases 2.3 times.
Activating Matrix-Degrading Enzymes: Hyperbaric oxygen also regulates matrix metalloproteinase expression. These are the enzymes that dismantle extracellular matrix proteins, and their activity is part of how the barrier around the tumor loosens.
Relieving the Hypoxia That Drives Resistance: Hypoxia activates HIF-1alpha, which upregulates drug metabolism genes such as ABCB1 and SLC22A1 and pushes chemotherapy drugs back out of tumor cells. Raising tumor oxygen partial pressure targets the upstream trigger for that cascade.
Specific Treatment Combinations
HBOT + Nanodrug Delivery: Nanoparticle carriers can deliver chemotherapy into tumor tissue, with temozolomide loaded onto porous silicon nanoparticles as one example the review covers. Poor drug penetration is the standing problem these carriers face, and improved oxygenation addresses the environment they have to cross.
HBOT + Engineered Bacteria: Engineered bacteria are one of the biomedical engineering platforms the authors group with nanodrug delivery and immune cell therapy as new strategies for reaching the tumor interior.
HBOT + Immunotherapy: Immunocellular therapy is limited by immunosuppressive tumor microenvironments. Relieving hypoxia improves the sensitivity of immunotherapy, and the softened matrix lets more immune cells enter.
HBOT + Photodynamic Therapy: Photosensitizers are among the payloads delivered by these engineering platforms into the tumor microenvironment that hyperbaric oxygen has improved the oxygenation of.
HBOT + Gene Editing: The review also covers delivery of gene editing tools such as CRISPR-Cas9 into an oxygenation-improved tumor microenvironment.
Safety Profile
The authors review safety issues alongside mechanism and clinical translation. They list optimizing individualized treatment plans, long-term efficacy evaluation, and molecular mechanism analysis as the priorities for future work. If you are considering hyperbaric oxygen as part of cancer care, that decision belongs with your treating oncologist and a hyperbaric medicine specialist, not with a review paper.
Practical Takeaways
- Hypoxia and a dense extracellular matrix are key factors limiting how well cancer treatment works
- Hyperbaric oxygen raises tumor oxygen partial pressure from about 5 mmHg to 30-50 mmHg
- It increases nanodrug penetration depth 1.8 times and immune cell infiltration 2.3 times
- The mechanism runs through reactive oxygen species generation and matrix metalloproteinase regulation, which degrade collagen and fibronectin
- Relieving hypoxia improves sensitivity to chemotherapy, radiotherapy, and immunotherapy
- This is a review of mechanism and early translation, and individualized protocols, long-term efficacy, and molecular mechanisms remain unresolved
Related Studies and Research
- Hypoxia and Inflammation
- Effects of Intermittent Hypoxia-Hyperoxia on Performance
- HBOT for Exercise Performance and Recovery: Meta-Analysis
- Hypoxia as Therapy for Mitochondrial Disease
FAQs
How does HBOT help drugs reach tumors better?
Hyperbaric oxygen induces reactive oxygen species and regulates matrix metalloproteinase expression, which degrades the collagen and fibronectin in the extracellular matrix around a tumor. That matrix is a physical barrier that blocks drugs. As it breaks down, tumor stiffness falls and nanodrug penetration depth increases 1.8 times.
Why does low oxygen make cancer harder to treat?
Hypoxia increases tumor cell resistance to chemotherapy drugs such as cisplatin by 2-3 times. It suppresses the reactive oxygen species that chemotherapy depends on, alters resistance-related genes and proteins through HIF-1alpha, and hinders drug delivery. It also makes tumors more invasive, promotes new blood vessel growth, and accelerates progression and metastasis.
Is HBOT for cancer treatment available now?
The combinations described in this review, hyperbaric oxygen with nanodrug delivery, engineered bacteria, immune cell therapy, photodynamic therapy, or gene editing tools, are not standard practice. The authors describe this as an interdisciplinary model still being pushed toward clinical application. Discuss with your oncologist whether a clinical trial might be appropriate for you.
What still needs to be worked out?
The authors name three priorities: optimizing individualized treatment plans, evaluating long-term efficacy, and analyzing the molecular mechanisms in more detail.
Bottom Line
This 2025 review in Frontiers in Oncology makes the case that hypoxia and a dense extracellular matrix are key factors limiting cancer treatment, and that hyperbaric oxygen addresses both. Raising tumor oxygen partial pressure from roughly 5 mmHg to 30-50 mmHg relieves the hypoxia that drives drug resistance, while reactive oxygen species generation and matrix metalloproteinase regulation degrade the collagen and fibronectin that wall the tumor off. Across the studies the authors collected, that combination increased nanodrug penetration depth 1.8 times and immune cell infiltration 2.3 times, and improved sensitivity to chemotherapy, radiotherapy, and immunotherapy. It is a promising direction rather than a finished one, and individualized protocols, long-term efficacy, and mechanism all remain open.
