This article is part of the HBOT Radar series, where we summarize the latest published hyperbaric oxygen therapy research.
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Disclaimer: This article is intended for educational and informational purposes only. It summarizes published medical research conducted in clinical settings and does not evaluate Brain Spa Hyperbaric products. The hyperbaric chambers offered on this website are non-medical wellness devices and are not intended to diagnose, treat, cure, or prevent any disease. Do not make medical decisions based on this article — consult a qualified healthcare professional.
📌 Stage IV Stomach Cancer. Chemo Wasn't Working. Then They Added Oxygen.
🔍 The story
A 62-year-old retired civil servant in Chengdu, China, went to the hospital in March 2022 with stomach pain. What followed was a diagnosis no one wants to hear: hepatoid adenocarcinoma of the stomach (HAS) — a rare, exceptionally aggressive subtype of gastric cancer that accounts for less than 1% of all stomach cancer cases. It's called "hepatoid" because the cancer cells look like liver cancer cells under the microscope, and it carries a worse prognosis than regular stomach cancer.
Surgery went well. The tumor was removed completely, and the patient completed six rounds of chemotherapy. For a while, it seemed like things were under control.
Then, in December 2023, the cancer came back — with a vengeance. His tumor marker AFP, which had been normal at 2.57 ng/ml, shot past 1,210 ng/ml (the lab's upper measurement limit). CT scans confirmed peritoneal metastasis — the cancer had spread to the lining of his abdomen. He was restaged to Stage IVB. The outlook was grim.
🌬️ The treatment
His oncology team at West China Hospital — one of China's top-ranked medical institutions — started aggressive treatment: CAPOX chemotherapy (capecitabine plus oxaliplatin) combined with sintilimab, a PD-1 immune checkpoint inhibitor. This is the standard first-line approach for advanced gastric cancer, backed by major Phase III trials.
After four cycles, imaging showed only "stable disease" — the cancer wasn't growing, but it wasn't shrinking either. For a cancer this aggressive, stable disease is essentially a ticking clock.
The team made a bold decision. They knew that one of the main reasons immune checkpoint inhibitors fail against tumors like HAS is hypoxia — the tumor's interior is starved of oxygen, which creates an environment that actively blocks the immune system from attacking cancer cells. Specifically, low oxygen triggers a pathway (HIF-1α) that recruits immunosuppressive cells, upregulates PD-L1 on cancer cells, and essentially makes the tumor invisible to the immune system.
So after the fifth cycle of immunochemotherapy, they added HBOT: 10 sessions at 2 ATA, one hour each, designed to flood the tumor with oxygen and — hopefully — make the checkpoint inhibitor actually work.
📊 What happened
The results were stunning.
After completing the sixth cycle of chemo plus immunotherapy — now with HBOT added — the follow-up CT scan in July 2024 showed complete resolution of all visible lesions. The tumor at the gastric anastomosis: gone. The peritoneal metastases: gone.
His AFP — the tumor marker that had been off-the-charts at >1,210 ng/ml for six straight months — dropped to 3.06 ng/ml. Normal range is 0-7. From unmeasurably high to completely normal.
A PET/CT scan in January 2025 showed no evidence of tumor recurrence anywhere in the body. An endoscopy of the remaining stomach showed no abnormalities. By every measure available — imaging, tumor markers, endoscopy — the cancer was gone.
The patient continued on maintenance therapy (capecitabine plus sintilimab) and reported no increase in side effects from the addition of HBOT. As of the last follow-up on March 29, 2025, he remains progression-free for over 15 months since the recurrence was diagnosed.
In oncology terms, this is a clinical complete response (cCR) by RECIST 1.1 criteria — the gold standard for evaluating cancer treatment outcomes.
🧠 What this case tells us — and what it doesn't
Why it matters:
The concept here is powerful and biologically well-grounded: tumors create their own oxygen-starved microenvironments that protect them from the immune system. HBOT reverses that protection — flooding the tumor with oxygen, downregulating the hypoxia pathways, and letting the immune checkpoint inhibitor do its job. The researchers call this "immunosensitization" — using oxygen to make immunotherapy work better.
What makes this case especially striking:
- Four cycles of immunochemotherapy alone = stable disease. The drug combination was working partially but had hit a ceiling.
- Adding HBOT = complete response. The same drugs, with oxygen added, produced a dramatically different outcome.
- AFP trajectory. Six consecutive months at >1,210 ng/ml, then plummeting to 3.06 after HBOT was added. The timing is hard to attribute to anything else.
- West China Hospital is a top-tier academic institution. This isn't a case report from an unverified clinic — it's from Sichuan University's flagship hospital, published in Frontiers in Immunology (impact factor 7.0).
- They've already launched a Phase Ib/II clinical trial (NCT06742411) to test this combination systematically. That's not something you do based on a fluke.
What it doesn't tell us:
- This is one patient. One. A complete response in a single case report cannot be generalized. It could be a remarkable coincidence — some patients do have delayed responses to immunotherapy without any additional intervention.
- No control comparison. We don't know what would have happened with a seventh and eighth cycle of immunochemotherapy alone. Perhaps the response was cumulative and would have occurred anyway.
- The patient had a specific genetic profile (RAD51D germline mutation, TP53 somatic mutation). Whether HBOT's immunosensitizing effect depends on tumor genetics is unknown.
- HAS is extremely rare. Even if HBOT works as an immunosensitizer in this cancer subtype, it may not translate to more common gastric cancers.
- Only 10 HBOT sessions at 2 ATA. If confirmed in the Phase Ib/II trial, the question of optimal dosing remains wide open.
The honest bottom line: This is the most dramatic single-patient outcome in recent HBOT cancer research. The mechanism is biologically plausible. The institutional credibility is high. And a formal trial is already underway. But it is still n = 1.
📌 Takeaway for the community
- A 62-year-old man with Stage IVB stomach cancer that had spread to his peritoneum showed only stable disease after four cycles of immunochemotherapy — the cancer wasn't shrinking
- After adding just 10 HBOT sessions (2 ATA, 1 hour each) as an "immunosensitizer," he achieved a complete clinical response — all visible cancer disappeared, tumor markers normalized
- The proposed mechanism: HBOT reduces tumor hypoxia, which removes the shield that protects cancer from immune checkpoint inhibitors
- He has remained progression-free for over 15 months, and the research team at West China Hospital has launched a Phase Ib/II clinical trial to test this approach in more patients
- This is a single case report — it cannot be generalized and could be coincidental, but the timing, mechanism, and institutional credibility make it a signal worth following
- This study was conducted in a clinical hospital setting under medical supervision — results cannot be directly applied to other settings or devices
Source: https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1625273/full
Li W, Wei J, Zhang P, Cheng M, Xu M, Zhu L, Liu M. Hyperbaric oxygen therapy as an immunosensitizing strategy in advanced gastric hepatoid adenocarcinoma: a case report. Front Immunol. 2025;16:1625273. doi: 10.3389/fimmu.2025.1625273.
Educational disclaimer
This content summarizes findings from published medical research for educational purposes only.
The hyperbaric chambers sold on this website are non-medical wellness devices and are not intended to diagnose, treat, cure, or prevent any disease.
The studies discussed here were conducted in clinical medical settings using medical-grade interventions. The inclusion of research summaries does not imply that similar outcomes can be achieved using non-medical wellness devices.
