Gut Microbiome in Gynecological Cancer Patients With Pelvic Toxicity: Controls Versus Ozone Treatment. (MicrOzoGineTox) (MicrOGineTox)

December 16, 2025 updated by: Bernardino Clavo, MD, PhD

Intestinal Microbiome Profiles in Women With Gynecological Tumors and Pelvic Toxicity Secondary to Radiotherapy and Chemotherapy: Comparison With Controls and Effect of Rectal Ozone Treatment.

Patients treated for gynecological tumors with radiotherapy (RT) and/or chemotherapy (CT) frequently develop pelvic toxicity (TPIRQT), a condition that can become persistent, progressive, and refractory to standard treatments. This toxicity, affecting the rectum (proctitis), bladder (cystitis), and vagina (mucositis), severely deteriorates quality of life. Standard options for refractory cases are limited; at our center, rectal ozone therapy is used with high rates of symptomatic improvement (66-75%). Emerging evidence suggests a link between gut microbiota and the development of TPIRQT. However, it is unknown how rectal ozone therapy may influence the gut microbiome or if this modulation is part of its therapeutic mechanism. This prospective observational study will investigate the potential relationship between gut microbiome profiles (composition and diversity), the presence and severity of TPIRQT, and the response to rectal ozone therapy.

Study Overview

Status

Not yet recruiting

Conditions

Detailed Description

Patients treated for gynecological tumors with radiotherapy (RT) and/or chemotherapy (CT) frequently develop pelvic toxicity (TPIRQT), a condition that can become persistent, progressive, and refractory to standard treatments. This toxicity, affecting the rectum (proctitis), bladder (cystitis), and vagina (mucositis), severely deteriorates quality of life. Standard options for refractory cases are limited; at our center, rectal ozone therapy is used with high rates of symptomatic improvement (66-75%). Emerging evidence suggests a link between gut microbiota and the development of TPIRQT. However, it is unknown how rectal ozone therapy may influence the gut microbiome or if this modulation is part of its therapeutic mechanism. This prospective observational study will investigate the potential relationship between gut microbiome profiles (composition and diversity), the presence and severity of TPIRQT, and the response to rectal ozone therapy.

Study Type

Observational

Enrollment (Estimated)

38

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

  • Name: Francisco Rodríguez-Esparragón, BSc, PhD
  • Phone Number: 34928449288
  • Email: afrodesp@gmail.com

Study Locations

  • Spain
    • Las Palmas
      • Las Palmas de Gran Canaria, Las Palmas, Spain, 35019
        • Hospital Universitario de Gran Canaria Dr. Negrín, (FIISC)
        • Contact:
        • Contact:
          • Francisco Rodríguez-Esparragón, BSc, PhD
          • Phone Number: 34928449288
          • Email: afrodesp@gmail.com
    • Tenerife
      • San Cristóbal de La Laguna, Tenerife, Spain, 38296
        • Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias - Universidad de La Laguna
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients with gynecological tumors treated with RT and/or CT with or without chronic pelvic toxicity (TPIRQT).

Description

Inclusion Criteria for all patients (Cases and Controls):

  1. Adult women (>=18 years).
  2. Diagnosed with gynecological tumors (any location and stage).
  3. Previously treated with radiotherapy and/or chemotherapy.

  4. Must accept and sign the specific informed consent for this study.

    Additional Inclusion Criteria for inclusion in the TPIRQT Group (Cases):

  5. Must present chronic TPIRQT with >= 3 months of duration after habitual symptomatic treatment.
  6. Must have a toxicity Grade of 2 (moderate symptoms, limiting instrumental ADL) or higher, according to the CTCAE v.5.0 scale.

Exclusion Criteria for all patients (Cases and Controls):

  1. Not meeting all inclusion criteria.
  2. Presence of active inflammatory bowel disease (e.g., Crohn's Disease, Ulcerative Colitis) or a history of major gastrointestinal resection (excluding appendectomy) that could significantly alter gut anatomy and microbiota.
  3. Any uncontrolled intercurrent illness or psychiatric condition that, in the investigator's opinion, would limit compliance with study requirements or interfere with the interpretation of results.
  4. Unwillingness or inability to provide written informed consent for study participation.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
TPIRQT Group (Cases)
Patients with gynecological tumors treated with RT and/or CT who develop chronic pelvic toxicity (TPIRQT) and are referred for compassionate-use rectal ozone therapy at the Chronic Pain Unit. Samples and data will be collected before and after ozone therapy
Control Group
pelvic toxicity (TPIRQT). This group will be matched by age (± 5 years) and primary tumor location. Samples and data will be collected once during a follow-up visit.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Comparison of gut microbiome profile (composition and diversity) between TPIRQT and Control groups
Time Frame: Baseline (single time point for controls, pre-ozone for cases)
Gut microbiome composition and diversity (from a single sample) in control patients will be compared to the baseline profile of patients with TPIRQT.
Baseline (single time point for controls, pre-ozone for cases)
Change in gut microbiome profile (composition and diversity) in patients with TPIRQT after rectal ozone therapy.
Time Frame: Baseline (pre-ozone therapy) , 4 Months (post-ozone therapy)
Gut microbiome composition and diversity will be analyzed from stool samples using 16S ribosomal RNA gene sequencing.
Baseline (pre-ozone therapy) , 4 Months (post-ozone therapy)
Correlation of gut microbiome profile with grade of pelvic toxicity.
Time Frame: Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
Toxicity will be assessed using: i) the CTCAE v.5.0 scale from the NCI , and ii) the EORTC QLQ-CX24 questionnaire. This will be evaluated for its relationship to microbiome data.
Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation of gut microbiome profile with health-related quality of life (HRQoL).
Time Frame: Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
HRQoL will be assessed using: i) the EQ-5D-5L questionnaire, and ii) the EORTC QLQ-C30 questionnaire. This will be evaluated for its relationship to microbiome data.
Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
Correlation of gut microbiome profile with anxiety and depression levels.
Time Frame: Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
Anxiety and depression will be assessed using the Hospital Anxiety and Depression Scale (HADS). This will be evaluated for its relationship to microbiome data.
Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
Correlation of gut microbiome profile with biochemical markers of oxidative stress and inflammation.
Time Frame: Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).
Serum samples will be collected to analyze biochemical parameters of oxidative stress and inflammation and their potential relationship with gut microbiome composition.
Baseline (for Control group); Baseline, 4 Months (for TPIRQT group).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Bernardino Clavo, MD, PhD

Collaborators

CIBER (Infectious diseases)
Dr. Negrin University Hospital
Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna
Fundacion Canaria Instituto de Investigacion Sanitaria de Canarias
Complejo Hospitalario Universitario Insular Materno Infantil (CHUIMI)

Investigators

  • Study Chair: Bernardino Clavo, MD, PhD, Hospital Universitario de Gran Canaria Dr. Negrín, (FIISC), Las Palmas, Spain
  • Principal Investigator: Francisco Rodríguez-Esparragón, BSc, PhD, Hospital Universitario de Gran Canaria Dr. Negrín, (FIISC), Las Palmas, Spain
  • Principal Investigator: Jacob Lorenzo-Morales, Prof, Instituto Universitario de Enfermedades Tropicales y Salud Publica de Canarias, Universidad La Laguna

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

January 15, 2026

Primary Completion (Estimated)

January 15, 2028

Study Completion (Estimated)

March 31, 2028

Study Registration Dates

First Submitted

November 21, 2025

First Submitted That Met QC Criteria

November 21, 2025

First Posted (Estimated)

December 2, 2025

Study Record Updates

Last Update Posted (Actual)

December 22, 2025

Last Update Submitted That Met QC Criteria

December 16, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2025-436-1
  • PIFIISC25/52 (Other Grant/Funding Number: FIISC (Fundación Canaria Inst. Investig. Sanitaria Canarias))
  • CIGC'25/26 (Other Grant/Funding Number: Cabildo de Gran Canaria (CIGC))

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

  • It will be available (after request): Individual participant data (IPD) that underlie the results reported in further articles, after deidentification
  • Data will be available after publication, ending 36 months following article publication.
  • They will be available for investigators whose proposed use of the data has been apd by an independent review committee identified for this purpose.

IPD Sharing Time Frame

Data will be available after publication, ending 36 months following article publication.

IPD Sharing Access Criteria

They will be available for investigators whose proposed use of the data has been approved by an independent review committee identified for this purpose

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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