Gut Microbiota Modulation via Rectal Ozone: A Proposed Clinical Study Protocol

Background: pelvic toxicity after cancer treatment

Radiotherapy and chemotherapy for gynaecological cancers can leave survivors with chronic pelvic toxicity - persistent bowel, bladder and pelvic symptoms that often resist conventional treatment. It is one of the more debilitating long-term consequences of successful cancer treatment.

One emerging idea is that this toxicity is linked to dysbiosis: a disruption of the balance of bacteria living in the gut. Ozone therapy given by rectal insufflation has anti-inflammatory and redox-modulating effects through what researchers call hormetic mechanisms - specifically Nrf2 activation and NF-kB inhibition. The authors hypothesise that part of ozone's clinical benefit in these patients comes from restoring gut microbial balance.

Study design: a proposed protocol, not yet results

This paper sets out the design for a study rather than reporting its findings. It is important to be clear about that: there are no outcomes to report yet.

The proposed study is prospective and observational, involving 38 patients. Nineteen will have chronic radiotherapy or chemotherapy-induced pelvic toxicity graded 2 or higher on the CTCAE v5.0 scale, and will receive rectal ozone therapy on a compassionate-use basis - approximately 40 sessions over four months, starting at an ozone concentration of 10 micrograms per millilitre and increasing from there.

The other nineteen are matched controls: patients treated with the same radiotherapy or chemotherapy, matched for age and primary tumour location, but without symptoms of pelvic toxicity.

What the study will measure

The protocol sets out to assess changes in gut microbiota composition following rectal ozone therapy, alongside inflammatory and oxidative stress markers, and patient-reported pelvic symptoms and quality of life.

The intervention may also include direct local application to affected mucosa - rectal, vesical or vaginal - following the standard protocol of the hospital's Chronic Pain Unit.

Why this protocol matters

Publishing a protocol before running a study is a marker of methodological seriousness. It commits the researchers to their design and outcome measures in advance, which makes the eventual results much harder to dispute.

It also signals that the ozone and gut microbiome question is now being investigated formally rather than anecdotally, at a hospital research unit, in a peer-reviewed journal.

Limitations

This is a study design, not evidence of effect. Nothing here demonstrates that rectal ozone insufflation modulates the gut microbiome in humans - that is the question the study intends to answer.

The proposed study is observational rather than randomised, with a small sample of 38 patients at a single centre. Results should be treated as preliminary when they appear.

This work concerns the management of side effects arising from cancer treatment. It does not examine ozone as a treatment for cancer itself. Ozone therapy is a complementary approach and should always be discussed with your oncology team.