Clinical trials

The main objective of this study is to analyze the impact on the health-related quality of life of patients with refractory symptoms who have been referred to the Dr. Negrín University Hospital Chronic Pain Unit for adjuvant palliative treatment with ozone therapy between January 2026 and December 2029. Additionally, the study aims to evaluate several specific symptoms, hyperspectral and thermal images, non-invasive clinical parameters related to the Autonomic Nervous System (such as heart rate variability, electrochemical skin conductance, and vibration perception thresholds), oxidative stress and inflammatory parameters, and gut microbiota composition.

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.

The main objective of this study is to analyze the impact on the health-related quality of life of patients with refractory symptoms, who have been referred to the HUGCDN Chronic Pain Unit for adjuvant palliative treatment with ozone therapy between June-2022 and December-2025

The main objective of this clinical trial is to evaluate the effectiveness and cost-effectiveness of adding ozone therapy to the clinical management of patients with pain secondary to chemotherapy-induced peripheral neuropathy

Gynecological cancers, including those affecting the ovaries, uterus, and cervix, represent a significant health burden for women. While survival rates have improved, many women experience chronic pelvic pain secondary to cancer treatment, especially radiotherapy and chemotherapy. This treatment-induced pelvic pain can be of difficult management and significantly affects patients' quality of life. In our experience, ozone therapy has emerged as a promising complementary treatment for pain relief in patients with chronic diseases, including side effects of cancer treatment. However, the genetic and epigenetic mechanisms influencing its effectiveness have not yet been thoroughly studied. The aim of this prospective study is to analyze how ozone therapy modulates the expression of certain genes and its impact on epigenetic clocks, which could help predict pain response.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating side effect of chemotherapy (CT), often requiring dose reductions or treatment interruptions, which can compromise efficacy of the planned CT (limiting its efficacy). Additionally, CIPN usually decreases patients' quality of life. Unfortunately, effective treatments for CIPN are limited. Emerging evidence suggests potential benefits of rectal ozone therapy and points to a possible role of the gut microbiome in CIPN development and treatment response. This observational study, ancillary to the randomized clinical trial (RCT) OzoParQT (NCT06706544), investigates the relationship between gut microbiome composition and CIPN severity in patients receiving rectal ozone therapy. Primary Objectives: To evaluate if gut microbiome profiles differ between patients: 1. with and without symptomatic improvement of CIPN. 2. receiving rectal ozone therapy and those receiving placebo. Secondary Objectives: To evaluate the relationship between gut microbiome composition and: 1. Health-related quality of life, 2. Anxiety and depression, 3. Biochemical markers of oxidative stress and inflammation. Main Trial Endpoints. Changes from baseline at the end of ozone therapy (week 16) in: * Gut microbiome profile * Patient-reported numbness and tingling * Neuropathy severity (QLQ-CIPN20 scale) * Paresthesia toxicity grade (CTCAE v.5.0) Secondary Trial Endpoints. Changes from baseline at the end of ozone therapy (week 16) in: * Patient-reported quality of life (EQ-5D-5L questionnaire) * Quality of life (QLQ-C30 questionnaire) * Anxiety and depression levels (HADS questionnaire) * Biochemical markers of oxidative stress * Biochemical markers of inflammation Trial Design: This observational study will analyze data from patients enrolled in the randomized, triple-blind, placebo-controlled OzoParQT clinical trial (NCT06706544). Trial Population in the OzoParQT trial (NCT06706544): Adults (≥18 years) with any tumor type, experiencing CIPN-related paresthesias (numbness and/or tingling), with a toxicity grade ≥ 2 according to the Common Terminology Criteria for Adverse Events (CTCAE v.5.0) for ≥ 3 months. Intervention in the OzoParQT trial (NCT06706544). All patients will receive standard care for their CIPN symptoms plus 40 sessions of rectal insufflation of an O3/O2 gas mixture over 16 weeks: * Ozone group: O3/O2 concentration increasing from 10 to 30 µg/mL * Control-placebo group: O2 only (0 µg/mL O3) Study Duration: Each patient will participate in this study (OzoParQTmicrob) for 16 weeks, concurrent with the ozone therapy intervention. The total planned project duration is 60 months.

The goal of this phase II/III randomized clinical trial is to evaluate the effect of adding rectal ozone therapy to the usual management of patients with paresthesia (numbness and/or tingling) due to chemotherapy-induced peripheral neuropathy (CIPN). Ozone treatment consists of the rectal insufflation of 180 - 300 milliliters of an ozone/oxygen gas mixture. The main questions to answer are: 1. Can ozone therapy improve patients' self-perceived level of numbness and tingling? 2. Can ozone therapy improve patients' self-perceived health-related quality of life (HRQoL)? In 42 patients with chronic numbness and tingling secondary to chemotherapy, the researchers will compare: * the addition of rectal ozone insufflations * versus the addition of rectal oxygen insufflations (placebo). Participants will receive 40 rectal gas (ozone versus oxygen) insufflations in 16 weeks and will continue other symptomatic or cancer treatments prescribed by their oncologists. Before treatment, after treatment, and 12 weeks after treatment, they will be evaluated: * Several questionnaires about neuropathy, quality of life, and anxiety and depression. * Biochemical parameters of oxidative stress and inflammation * Hyperspectral images of hands and feet * Toxicity of procedure.