Trial Results Cast Doubt On Hyperbaric Oxygen For Radiation-Induced Bowel Dysfunction

Hyperbaric oxygen trial fails to show benefits for patients with chronic bowel issues after pelvic radiotherapy

medwireNews: Researchers challenge the use of hyperbaric oxygen for patients with chronic bowel dysfunction after pelvic radiotherapy following negative phase III trial results.

There was no significant difference in the outcomes of 55 patients randomly assigned to receive 40 sessions of 100% oxygen at 2.4 atmospheres of absolute pressure (ATA) lasting 90 minutes over 8 weeks and 29 patients who were given a sham treatment consisting of 21% oxygen at 1.3 ATA, the researchers report in The Lancet Oncology.

Between baseline and 12 months, the active and sham treatment groups both achieved a median 4-point change in their scores on the bowel component of the modified Inflammatory Bowel Disease Questionnaire (IBDQ).

And there was no significant difference in the median change in the overall or rectal bleeding IBDQ scores after 12 months between the hyperbaric oxygen and sham treatment groups, report John Yarnold, from the Institute of Cancer Research in London, UK, and HOT2 co-investigators.

Noting that the results contrast with those of the HORTIS trial and are “inconsistent” with anecdotal and review data collected from non-randomised trials, the team highlights the “urgent need for more level 1 evidence to determine with confidence whether hyperbaric oxygen therapy can be recommended as a standard of care for this group of patients”.

Carien Creutzberg, from Leiden University Medical Centre in the Netherlands, applauds the HOT2 investigators in an accompanying comment, citing their use of a sham-controlled study design, 12-month follow-up duration and careful inclusion only of participants whose symptoms could not be controlled using standard care.

“This approach might have led to a highly selected study population of patients with long-lasting, difficult symptoms, but these are the typical patients who would qualify for referral for hyperbaric oxygen therapy”, she observes.

While acknowledging that the results are “disappointing”, the commentator discusses the importance of the study, adding: “The results are especially relevant with respect to the burden that undergoing hyperbaric oxygen therapy can be for patients (at least 6–8 weeks of daily treatments, with risk of [transient] vision changes and ear problems) and for health-care providers, given the significant cost of hyperbaric oxygen therapy.”


Glover M, Smerdon GR, Andreyev HJ, et al. Hyperbaric oxygen for patients with chronic bowel dysfunction after pelvic radiotherapy (HOT2): a randomised, double-blind, sham-controlled phase 3 trial. Lancet Oncol 2015; Advance online publication 15 December. DOI:

Creutzberg CL. Hyperbaric oxygen therapy for radiation-induced injury: evidence is needed. Lancet Oncol 2015; Advance online publication 15 December.

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