TL;DR: April is Daffodil Month – a time to recognise the resilience of Canadian cancer survivors and the long-term effects many live with after treatment. Hyperbaric oxygen therapy (HBOT) is a proven, often publicly covered treatment for delayed radiation injury that too few survivors know about. This post explains what it is, who it helps, and how to access it across Canada.
Estimated reading time: 6 minutes
More than half of all Canadians diagnosed with cancer today will survive. That is a remarkable achievement – a testament to decades of research, early detection, and better treatments. But survival is not the end of the story.
For the estimated 1.5 million Canadians living with and beyond cancer, the effects of treatment can last years or even decades after the final radiation session or chemotherapy cycle ends. Radiation therapy, one of the most effective tools in oncology, saves lives – but it can also leave lasting damage to healthy tissue surrounding the tumour. This damage, called delayed radiation injury, affects bladders, bowels, jaws, skin, and soft tissue, and it can emerge months or years after treatment.
April is Daffodil Month – the Canadian Cancer Society’s signature awareness and fundraising campaign, now in its 65th year. The daffodil is a symbol of hope, renewal, and resilience. At Canada Hyperbarics, we believe that hope must extend beyond diagnosis and treatment – it must include helping survivors heal from the lasting effects of the treatments that saved their lives.
This month, we are dedicating our entire blog series to the intersection of cancer survivorship and hyperbaric oxygen therapy. This first post is for every Canadian who has been through radiation therapy and may not know that a proven healing option exists.
What Is Delayed Radiation Injury?
Radiation therapy works by damaging the DNA of cancer cells so they cannot grow. But radiation does not distinguish perfectly between cancer cells and healthy tissue. Over time, the tiny blood vessels in the irradiated area deteriorate, reducing oxygen supply to surrounding tissue. This progressive vascular damage is called delayed radiation injury – and it can appear 6 months to 30 or more years after treatment ends.
The most common forms include:
| Condition | What It Affects | Common Symptoms |
|---|---|---|
| Radiation cystitis | Bladder | Blood in urine, urgency, pain |
| Radiation proctitis | Rectum | Rectal bleeding, urgency, pain |
| Osteoradionecrosis | Jaw or bone | Exposed bone, pain, infection |
| Soft tissue necrosis | Skin, muscle, chest wall | Non-healing wounds, fibrosis, pain |
A 2025 systematic review of HBOT for late radiation tissue injury affecting the bowel and bladder found that hyperbaric oxygen produced measurable clinical improvement in the majority of patients treated (Systematic Review, 2025).
Key takeaway: If you received radiation therapy at any point in your life – even decades ago – you may be at risk for delayed radiation injury, and there is a treatment that can help.
How Does Hyperbaric Oxygen Therapy Help?
HBOT works by delivering 100% pure oxygen at increased atmospheric pressure inside a specialised chamber. This dramatically increases the oxygen dissolved in your blood – up to 10 to 15 times normal levels. When this oxygen-rich blood reaches radiation-damaged tissue, it triggers a powerful healing response: the growth of entirely new blood vessels, a process called angiogenesis.
Over a course of treatment – typically 60 sessions for radiation injury – your body builds a new vascular network in the damaged area, restoring oxygen and nutrient supply to tissue that had been slowly dying.
Did you know? Radiation injury can appear up to 30 years after treatment ends – making HBOT relevant long after active cancer care concludes.
A 2023 Cochrane review – the gold standard of evidence synthesis – confirmed that HBOT improves outcomes for patients with late radiation tissue injury, particularly for radiation cystitis, proctitis, and osteoradionecrosis (Bennett et al., 2023).
Research published in 2022 also demonstrated significant improvements in symptom burden and health-related quality of life in cancer survivors with pelvic radiation injuries after completing HBOT (Radiation Tissue Injury Symptom Study, 2025).
Is HBOT Safe for Cancer Survivors?
One of the most common concerns among cancer survivors is whether breathing concentrated oxygen could promote cancer growth. The evidence is reassuring.
A 2025 safety evaluation specifically examining HBOT for managing cancer treatment complications found no evidence that hyperbaric oxygen promotes tumour growth or recurrence (Safety Evaluation, 2025). In fact, some preclinical research suggests that the high-oxygen environment created during HBOT may actually be hostile to certain tumour types.
HBOT has been used safely in cancer survivors for decades. The Undersea and Hyperbaric Medical Society (UHMS) lists delayed radiation injury as one of its 14 approved indications – a designation based on extensive clinical evidence.
Is HBOT Covered in Canada?
Coverage for HBOT varies by province, but delayed radiation injury is one of the most widely covered indications across the country.
- Ontario covers all 14 UHMS-approved indications through OHIP – at both hospital and approved private facilities
- Alberta covers approved indications at hospital-based and CPSA-accredited private facilities
- Quebec, British Columbia, Nova Scotia, and Newfoundland cover HBOT at hospital-based facilities for approved indications
- Other provinces may provide coverage through interprovincial referral
For a complete province-by-province breakdown, visit the Canada Hyperbarics coverage guide.
Frequently Asked Questions
Can I get HBOT years after my radiation treatment ended?
Yes. There is no upper time limit. Patients have been successfully treated 10, 20, and even 30+ years after completing radiation therapy. Delayed radiation injury can develop at any point, and HBOT can help at any stage.
How do I get a referral for HBOT?
Ask your oncologist, radiation oncologist, or family doctor for a referral to a hyperbaric medicine programme. The referral should include your radiation treatment dates, fields, total dose, and current symptoms.
How many sessions will I need?
A standard radiation injury treatment protocol involves 60 hyperbaric sessions, delivered once daily on weekdays over approximately 12 weeks. Additional cycles may be recommended after a 3-month rest period.
Does HBOT hurt?
No. Most patients describe sessions as comfortable and relaxing. You may feel mild ear pressure during pressurisation, similar to descending in an airplane. Sessions last about 90 to 120 minutes.
Is HBOT safe if I still have cancer?
HBOT is approved for treating radiation injury in cancer survivors. A 2025 safety evaluation found no evidence that HBOT promotes tumour growth. Always discuss with your oncologist before starting any new treatment.
This Daffodil Month, Let Hope Bloom
Cancer survival rates in Canada are better than ever – but survival means more than a clear scan. For the millions of Canadians living with the lasting effects of radiation therapy, hyperbaric oxygen therapy offers a path to genuine healing: new blood vessels, restored tissue, reduced pain, and improved quality of life.
If you or someone you love received radiation therapy for cancer – at any point, for any cancer type – HBOT may be worth discussing with your care team. You do not need to be currently unwell. You do not need to wait for symptoms to worsen. Treatment is available, and in many provinces, it is covered.
Find a hyperbaric facility near you across Canada.
This April, in recognition of Daffodil Month, canadahyperbarics.ca is proud to support the Canadian Cancer Society’s mission to help hope bloom for every Canadian affected by cancer.
References
- Systematic Review of Hyperbaric Oxygen for Late Radiation Tissue Injury (Bowel, Bladder). (2025). View in Canada Hyperbarics Research Database.
- Bennett MH, Feldmeier J, Hampson NB, et al. Hyperbaric oxygen therapy for late radiation tissue injury. Cochrane Database of Systematic Reviews. 2023. View in Canada Hyperbarics Research Database.
- Reduced Symptoms of Late Radiation Tissue Injury of the Vagina After Treatment With Hyperbaric Oxygen Therapy: A Retrospective Analysis. (2025). View in Canada Hyperbarics Research Database.
- Hyperbaric Oxygen Therapy for Managing Cancer Treatment Complications: A Safety Evaluation. (2025). View in Canada Hyperbarics Research Database.
This content is for informational purposes only and does not constitute medical advice. Hyperbaric oxygen therapy should only be administered by qualified healthcare professionals in accredited facilities. Consult your physician or a certified hyperbaric medicine specialist for treatment decisions. Canada Hyperbarics is an independent educational resource and is not affiliated with any specific clinic or manufacturer.