Colorectal cancer (CRC) patients undergoing chemotherapy often experience anemia, oxidative stress, and immune suppression, significantly impacting their quality of life and treatment outcomes. Normobaric oxygen (NBO) therapy, which delivers oxygen at atmospheric pressure with elevated oxygen concentration, has shown a potential to enhance erythropoiesis, reduce oxidative stress, and modulate immune function. However, its efficacy in CRC patients remains underexplored. This study aims to evaluate the effects of NBO exposures on (1) supporting erythropoiesis by measuring erythropoietin (EPO) levels and hypoxia-inducible factors (HIF-1α), (2) reducing oxidative stress and improving stress and emotional well-being, and (3) modulating immune function by assessing cytokine profiles. Secondary objectives include assessing the impact of NBO on patient-reported outcome measures (PROMs) such as stress, anxiety, depression, and quality of life. This is a prospective, randomized, double-blind, placebo-controlled clinical trial. A total of 254 CRC patients undergoing chemotherapy will be randomized 1:1 to receive either active NBO therapy (n=127) or placebo NBO therapy (n=127). The intervention consists of 10 NBO sessions over five weeks. Primary outcomes include biomarkers of erythropoiesis, oxidative stress, and immune response. Secondary outcomes assess quality of life and psychological well-being. Data will be collected at baseline, mid-intervention, post-intervention, and during two follow-up visits (3- and 6-months post-intervention). The study hypothesizes that NBO therapy will improve erythropoiesis, reduce oxidative stress, and enhance immune function in CRC patients, leading to improved quality of life and clinical outcomes. Findings from this trial may establish NBO as a novel supportive therapy for CRC patients undergoing chemotherapy.
The intervention will involve NBO as a supportive treatment for CRC patients undergoing chemotherapy. The NBO protocol consists of regular sessions in a normobaric chamber where patients are exposed to controlled oxygen levels aimed at reducing ox-idative stress, supporting erythropoiesis, and modulating immune function. Patients in the CRC group will undergo 10 NBO sessions across five weeks, with two sessions weekly. Patient's exposure to NBO conditions in group 1 (aNBO) including: oxygen levels of 32-40% (compared to about 21% in the atmosphere), pressure maintained at 1,500 hPa (about 1,000 hPa outside), carbon dioxide levels between 0.7-1.9% (compared to 0.03% in the atmosphere, and hydrogen levels between 0.5-1% (which is 10 to 20 thousand times higher than in the atmosphere). Exposure time in the NBO chamber will be the standard 2 hours with an additional 20 minutes for preparation and adaptation and 10 minutes for the finalization and decompression period. Patients' exposure to atmospheric conditions in the same NBO chamber (without normobaric conditions to provide sham-placebo intervention) in group 2 (pNBO): oxygen levels about 21%, pressure maintained at about 1,000 hPa, carbon dioxide levels about o 0.03%, and hydrogen levels about 0.00005% (0.5 parts per million, like in the atmos-phere). The primary comparator in this study is the placebo NBO group (CRC patients; n=127) for CRC patients, which serves to differentiate the specific effects of active NBO from the natural course of treatment without enhanced oxygen exposure. The patient assessment scheme contains six visits from V0 to V5 with subsequent analytical packages with detailed explanation in 2.8. section. The patient assessment schedule consists of six visits, from V0 to V5, each including specific evaluations and interventions. The study begins with V0 (prequalification/screening), where patient consent is obtained, medical history is collected, and baseline data are recorded. V1 (randomization and pre-test visit) involves the initial assessments, including anemia, stress, immune, genetic markers, and patient-reported outcomes (PROMs). Following this, the first phase of the NBO intervention (sessions 1-5) takes place over five weeks. At V2 (midpoint evaluation), the same set of assessments is repeated to track progress, followed by the second phase of the NBO intervention (sessions 6-10) conducted over the next five weeks. V3 (finalization and post-test visit) marks the completion of the intervention, with a final round of primary and secondary outcome assessments. The study then proceeds with two follow-up visits: V4 (3-months post-NBO) and V5 (6-months post-NBO), where anemia, stress, immune, genetic markers, and PROMs are reassessed to evaluate the long-term effects of the intervention.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
TRIPLE
Enrollment
254
Patient's exposure to NBO conditions in group 1 (aNBO) including: oxygen levels of 32-40% (compared to about 21% in the atmosphere), pressure maintained at 1,500 hPa (about 1,000 hPa outside), carbon dioxide levels between 0.7-1.9% (compared to 0.03% in the atmosphere, and hydrogen levels between 0.5-1% (which is 10 to 20 thousand times higher than in the atmosphere). Exposure time in the NBO chamber will be the standard 2 hours with an additional 20 minutes for preparation and adaptation and 10 minutes for finalization and the decompression period.
Patients' exposure to atmospheric conditions in the same NBO chamber (without normobaric conditions to provide placebo intervention as the study comparator) in group 2 (pNBO): oxygen levels about 21%, pressure maintained at about 1,000 hPa, carbon dioxide levels about o 0.03%, and hydrogen levels about 0.00005% (0.5 parts per million, like in the atmos-phere).
4th Military Clinical Hospital
Wroclaw, Poland
Erythropoietin (EPO) concentration
Erythropoietin (EPO) concentration \[mU/mL\] will be measured using a quantitative immunoassay (ELISA) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Hypoxia-inducible factor-1α (HIF-1α)
Hypoxia-inducible factor-1α (HIF-1α) \[ng/mL\] will be measured using a quantitative immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Reticulocyte count
Reticulocyte count \[% of total red blood cells\] will be measured using an automated hematology analyzer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Red blood cell (RBC)
Red blood cell (RBC) count \[10¹² cells/L\] will be measured using 5-part differential blood morphology on an automated hematology analyzer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Hemoglobin concentration (HGB)
Hemoglobin concentration (HGB) \[g/dL\] will be measured using an automated hematology analyzer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Hematocrit
Hematocrit \[%\] will be measured using an automated hematology analyzer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Serum creatinine
Serum creatinine \[µmol/L\] will be measured using an enzymatic assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Estimated glomerular filtration rate (eGFR)
Estimated glomerular filtration rate (eGFR) \[mL/min/1.73 m²\] will be calculated using the CKD-EPI equation at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Alanine aminotransferase (ALT)
Alanine aminotransferase (ALT) \[IU/L\] will be measured using an enzymatic assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Aspartate aminotransferase (AST)
Aspartate aminotransferase (AST) \[IU/L\] will be measured using an enzymatic assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Fasting glucose
Fasting glucose \[mmol/L\] will be measured using a hexokinase assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Fasting insulin
Fasting insulin \[µU/mL\] will be measured using an immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Lipid profile
Lipid profile (total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides) \[mmol/L\] will be measured using enzymatic/colorimetric assays at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Iron metabolism (serum iron, total iron-binding capacity [TIBC]
Iron metabolism (serum iron, total iron-binding capacity \[TIBC\] \[µmol/L\], ferritin \[ng/mL\], vitamin B₁₂ \[pg/mL\]) will be measured using immunoassays at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Serum albumin
Serum albumin \[g/L\] will be measured using a bromcresol green assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
C-reactive protein (CRP)
C-reactive protein (CRP) \[mg/L\] will be measured using a high-sensitivity immunoturbidimetric assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Reactive oxygen species (ROS) level
Reactive oxygen species (ROS) level \[relative fluorescence units\] will be measured using a chemiluminescence assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up]
Serum cortisol
Serum cortisol \[µg/dL\] will be measured using a high-sensitivity immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Gamma-aminobutyric acid (GABA)
Gamma-aminobutyric acid (GABA) \[µmol/L\] will be measured using an enzyme-linked immunosorbent assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Dopamine
Dopamine \[ng/mL\] will be measured using a competitive immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Serotonin
Serotonin \[ng/mL\] will be measured using a competitive immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Fibrinogen
Fibrinogen \[g/L\] will be measured using the Clauss clotting assay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Glycated hemoglobin (HbA₁c)
Glycated hemoglobin (HbA₁c) \[%\] will be measured using high-performance liquid chromatography at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Dehydroepiandrosterone-sulfate (DHEA-S)
Dehydroepiandrosterone-sulfate (DHEA-S) \[µg/dL\] will be measured using an immunoassay at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Systolic blood pressure (SBP)
Systolic blood pressure (SBP) \[mmHg\] will be measured using an automated sphygmomanometer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Diastolic blood pressure (DBP)
Diastolic blood pressure (DBP) \[mmHg\] will be measured using an automated sphygmomanometer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Heart rate (HR)
Heart rate (HR) \[beats per minute\] will be measured using an automated sphygmomanometer at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Body mass index (BMI)
Body mass index (BMI) \[kg/m²\] will be calculated from measured weight and height at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Body surface area (BSA)
Body surface area (BSA) \[m²\] will be calculated using the Mosteller formula from measured weight and height at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Waist-to-hip ratio (WHR)
Waist-to-hip ratio (WHR) \[ratio\] will be calculated from measured waist and hip circumferences at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Tumor necrosis factor-α (TNF-α)
Tumor necrosis factor-α (TNF-α) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Interleukin-1β (IL-1β)
Interleukin-1β (IL-1β) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Interleukin-6 (IL-6)
Interleukin-6 (IL-6) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Interleukin-10 (IL-10)
Interleukin-10 (IL-10) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Monocyte chemoattractant protein-1 (MCP-1/CCL2)
Monocyte chemoattractant protein-1 (MCP-1/CCL2) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Macrophage inflammatory protein-1α (MIP-1α/CCL3)
Macrophage inflammatory protein-1α (MIP-1α/CCL3) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Macrophage inflammatory protein-1β (MIP-1β/CCL4)
Macrophage inflammatory protein-1β (MIP-1β/CCL4) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Vascular endothelial growth factor A (VEGF-A)
Vascular endothelial growth factor A (VEGF-A) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Platelet-derived growth factor-BB (PDGF-BB)
Platelet-derived growth factor-BB (PDGF-BB) \[pg/mL\] will be measured using a multiplex immunoassay (Luminex) at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Stress level (self-assessment)
The Perceived Stress Questionnaire (PSQ-30) is a 30-item self-report instrument designed to assess perceived stress over the previous month. Each item is rated on a 4-point Likert scale (1 = "almost never" to 4 = "usually"), yielding a raw score that can range from 30 (minimum) to 120 (maximum). Higher raw scores indicate greater perceived stress (worse outcome). The PSQ-30 will be administered at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Anxiety and depression levels (self-assessment)
The Hospital Anxiety and Depression Scale (HADS) is a 14-item self-report questionnaire comprising two subscales: HADS-Anxiety (HADS-A) and HADS-Depression (HADS-D). Each subscale contains 7 items scored on a 4-point Likert scale (0 = "not at all" to 3 = "very often"), yielding subscale scores from 0 (minimum) to 21 (maximum). Higher scores indicate greater symptom severity (worse outcome). The HADS total score (sum of HADS-A and HADS-D) ranges from 0 to 42. The HADS will be administered at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
Quality of live level (self-assessment)
EuroQol Five-Dimension Five-Level questionnaire (EQ-5D-5L) index score \[-0.59 to 1.00; higher = better health\] will be derived from five domains-mobility, self-care, usual activities, pain/discomfort, and anxiety/depression-each rated on a 5-point scale (1 = no problems to 5 = extreme problems). Health states will be converted to a single index value using the Polish EQ-5D-5L value set. The EQ-5D-5L will be administered at V1, V2, V3, V4, and V5.
Time frame: From enrollment to the end of 6th month follow-up
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