Patients with chronic gastrointestinal complaints caused by pelvic radiotherapy may not benefit from the standard high-pressure oxygen therapy that has been used for decades, a study has suggested.
Researchers from The Institute of Cancer Research, London, and The Royal Marsden, working with others around the UK, found hyperbaric oxygen did not improve symptoms any more than a sham therapy.
The findings, published in The Lancet Oncology, challenge existing evidence for current practice and highlight an “urgent need” for further high-quality research to determine the value of hyperbaric oxygen as a standard of care, according to study authors.
The HOT2 trial received funding from Cancer Research UK and through the NIHR Biomedical Research Centre at The Royal Marsden and the ICR.
Up to a third of patients develop chronic gastrointestinal problems after pelvic radiotherapy for conditions such as rectal, prostate, bladder or ovarian cancers.
In hyperbaric oxygen therapy, a patient enters a pressurised chamber that increases oxygen intake to promote healing. It has been widely used for years to treat symptoms such as pain, bloating, faecal incontinence and rectal bleeding following pelvic radiotherapy – but most studies of the treatment have been retrospective with only two randomised trials conducted in this particular setting.
The new phase III trial included 84 adults who had moderate or severe chronic gastrointestinal symptoms for 12 months or more after radiotherapy and no evidence of cancer recurrence. All participants had first undergone three months of unsuccessful medical therapy for the symptoms.
A total of 55 participants were randomised to eight weeks of hyperbaric therapy and 29 to a sham treatment involving breathing regular air.
Researchers analysed data from a patient questionnaire on gastrointestinal symptoms and found no clinically relevant benefit for overall bowel function or rectal bleeding from hyperbaric oxygen therapy over the sham treatment. Both groups saw an average improvement in symptom score of 4 on the 70-point scale over 12 months – considered to be too small to be clinically relevant.
Although some adverse events were recorded, none were linked to treatment.
The researchers said more randomised trials were needed to determine “with confidence” whether the therapy could continue to be recommended for these patients.
Chief investigator Professor John Yarnold, Professor of Clinical Oncology at the ICR and an honorary consultant at The Royal Marsden NHS Foundation Trust, said: “This trial detected no evidence of beneficial effect from the use of hyperbaric oxygen in patients with radiation-induced chronic gastrointestinal symptoms.
“This one study doesn’t exclude the possibility that hyperbaric oxygen can be an effective treatment for gastrointestinal symptoms experienced by these patients. But further, high-quality evidence from randomised trials is urgently needed to fully explore the value of this intervention as standard care.”