Hyperbaric oxygen therapy (HBOT) is a medical treatment involving breathing pure oxygen in a specialized chamber with increased air pressure. This environment significantly increases the amount of oxygen dissolved in the bloodstream. HBOT is used for various medical conditions where enhanced oxygen delivery promotes healing.
How Hyperbaric Oxygen Therapy Works in the Body
HBOT works based on two main factors: increased ambient pressure and increased inspired oxygen concentration. Normal air contains about 21% oxygen, but in a hyperbaric chamber, patients breathe nearly 100% oxygen. The pressure inside the chamber is raised to two to three times normal atmospheric pressure (1.5 to 3 atmospheres absolute, or ATA).
This elevated pressure, combined with pure oxygen, allows more oxygen to dissolve directly into the blood plasma, independent of hemoglobin. Normally, oxygen is primarily carried by red blood cells bound to hemoglobin. By increasing dissolved oxygen in plasma, oxygen can reach tissues with compromised blood flow or those deprived of adequate oxygen. This process, known as hyperoxia, supports cellular functions, promotes new blood vessel growth, reduces swelling, and enhances infection fighting.
HBOT in Cancer Care: Current Applications
Within cancer care, HBOT is primarily used as a supportive therapy rather than a standalone cancer treatment. Its established applications focus on managing side effects from conventional cancer treatments, particularly radiation therapy. Radiation can damage healthy tissues surrounding a tumor, leading to conditions that may appear months or even years after treatment.
HBOT is frequently used to treat radiation-induced tissue damage, such as osteoradionecrosis (bone death, especially in the jaw following head and neck cancer treatment). It also addresses radiation cystitis, characterized by persistent urinary bleeding after pelvic radiation. The therapy helps by stimulating new blood vessel growth (angiogenesis) and improving oxygen supply to these damaged areas, which can be scarred and have restricted blood flow. HBOT can also promote wound healing after cancer surgeries and is explored for its potential to reduce general side effects of chemotherapy and radiation, such as “chemo brain.”
Scientific Understanding and Research on HBOT and Cancer Growth
The question of whether HBOT directly affects cancer growth is a subject of ongoing scientific investigation and debate. Early concerns existed that increasing oxygen might inadvertently promote tumor growth, given that oxygen is involved in wound healing and general tissue repair. However, systematic reviews have concluded that HBOT does not appear to stimulate tumor growth or increase the risk of cancer recurrence.
Some research suggests HBOT might have tumor-inhibitory effects in certain cancer subtypes. Tumors often exist in low-oxygen (hypoxic) environments, which can make them more resistant to conventional therapies like radiation and chemotherapy. By delivering high levels of oxygen, HBOT could re-oxygenate these hypoxic tumor regions, making cancer cells more susceptible to treatment and improving the effectiveness of standard therapies. Conversely, some studies, particularly in preclinical models, have shown mixed results, with a few indicating accelerated tumor growth post-therapy in specific conditions, though no cancer-enhancing effect was observed during the actual HBOT exposure period.
Important Considerations for Patients
Patients considering HBOT, especially those with a cancer diagnosis, should be aware of potential side effects and the need for medical consultation. Common side effects include temporary changes in vision, ear barotrauma (pressure-related ear discomfort similar to airplane travel), and mild sinus discomfort. More rarely, oxygen toxicity can occur, leading to seizures or lung issues, though these are uncommon with standard protocols.
It is essential to consult with an oncologist and other medical professionals before pursuing HBOT. The therapy is not a standalone cure for cancer and should not be used as a substitute for conventional cancer treatments like surgery, chemotherapy, or radiation. HBOT is generally considered safe for patients with malignancies, but its application should always be part of a comprehensive treatment plan, addressing specific indications and potential risks.