Significant strides have been made in cancer treatment with the discovery of new anti-cancer agents and the development of combination protocols that include radiotherapy (RT) ¹. However, due to the side effects of methods such as chemotherapy (CT) and RT used in cancer treatment, it both makes it difficult for patients to comply with treatment and leads to patients quit the treatment ². In addition, delays in wound healing in cancer patients who have undergone surgical intervention also delay the initiation of CT and RT ³. On the other hand, adjuvant treatments are needed for some patients when CT and RT are insufficient. All of these processes increase the importance of additional supportive treatment in tumor treatment.

Traditional and Complementary Medicine (TCM) has become increasingly popular among cancer patients in recent years ³. The increasing number of clinical studies has attracted the interest of oncologists in TCM ⁴. Among TCM treatments, ozone therapy (OT) has attracted even more attention from physicians, as it has a certain standardization and has been the subject of extensive scientific research.

Ozone gas was first discovered by German chemist Christian Fredrick Schönbein in 1840 and was initially used for water disinfection and disinfection in operating rooms ⁵. Later on, ozone gas began to be used for treatment and support purposes in diseases, and the first ozone study was conducted in 1949. OT studies on cancer treatment also began in 1961 ⁶.

This study aims to review all scientific studies on cancer conducted on PubMed to assess the role of OT in cancer patients before, during, and after treatment.

This meta-analysis investigates the use of OT in cancer treatment by analyzing data from the Pub-Med database. The analysis includes all relevant studies conducted between 1940 and 2024, and only studies classified as "Case Reports, Classic Article, Clinical Trial, Comparison Study, Meta-analysis, Observational Study, Randomized Controlled Trial, Review" in the Pub-Med filtering section are included. Our aim is to examine the use of OT in cancer treatment, including its role in primary cancer treatment, management of CT and RT side effects, general support and symptomatic treatment of cancer patients, and pre- and post-operative care. FİNDİNGS 133 OT studies on cancer were found. 17 of these studies were conducted as randomized controlled trials (RCTs). There were also 5 compilations on the topic of OT and cancer. Most randomized controlled trials are based on animal experiments. One of these studies, a study conducted on mice with colon cancer, studied the effect of ozone water on tumor hypoxia alone and in combination with an antitumor drug.7 The mice were divided into 6 groups (n:8). 1. Group; sterile salt water group, 2. Group; ozone water group, 3. Group; sterile saline + 5 mg cisplatin (CDPP), 4. Group; ozonated water + 5 mg cisplatin, 5. Group; ozonated water + 3.7 mg cisplatin, 6.Group; ozonated water + 1.7 mg cisplatin. Saline and ozone applications were made intraperitoneal. There was no significant difference between the effect of intraperitoneal physiological serum and ozone administration on tumor growth rate, but intraperitoneal ozone + 5 mg cisplatin administration gave more significant results compared to physiological serum + cisplatin administration (Table 1) 7. In the same study, mice were divided into 2 groups of 10 to investigate the effect of ozone water on intratumoral blood perfusion and intratumoral oxygen partial pressure. 1. Group intraperitoneal ozonated water, 2. The group is a sterile salt water group. Ozone water has been shown to increase intratumoral blood perfusion and improve intratumoral oxygen partial pressure (Table 1) 7. In a pilot study investigating the effect of OT on tumor hypoxia, 18 patients with accessible metastases or advanced tumors were included in the study (14 with head and neck tumors, 2 with gynecological tumors, and metastases in two chest wall areas). OT was applied for three days by autohemotransfusion and tumor tissue oxygen saturation was measured before and after the session As a result, hemoototransfusion has been shown to reduce OT tumor hypoxia (Table 1) 8. In another RCT, the effectiveness of OT in RT-related testicular damage was investigated. In this study, 30 rats were randomly divided into 5 groups. Group OT: Intraperitoneal ozone was administered to determine the effect of OT on testicular histopathology. Group RT: scrotal irradiation was applied to rats to determine the effect of RT on testicular histopathology. Group RT + OT (OT after RT): Rats were given scrotal irradiation and intraperitoneal OT after RT to determine the effect of OT after RT on testicular histopathology. Group OT + RT (RT after OT): Rats were given intraperitoneal OT and scrotal irradiation after OT to determine the effect of preradiotherapeutic OT on testicular histopathology. Group C (control): The rats were given intra-peritoneal oxygen as a control. (RT: Radiotherapy, OT: Ozone therapy). The results were evaluated by testicular interstitial fluid and interstitial edema, desquamation of germinal cells and irregular spaces in the epithelium, seminiferous tubules containing spermatogenic cells and sertoli cells, and germ cell necrosis level. In addition, thiobarbituric acid-reactive substances, glutathione, superoxide dismutase, catalase and glutathione peroxidase levels were compared. Significant testicular damage was detected in the RT group. Both right and left testicular weights were significantly reduced in the RT group. However, it has been concluded that it significantly prevents these decreases caused by OT radiation before and after RT (Table 1). The levels of thiobarbituric acid-reactive substances (TBARS) in rat testicular tissue were significantly higher, while the levels of GSH, SOD, catalase and GPx were significantly lower in the RT group compared to the C group. On the other hand, a significant decrease in TBARS level and an increase in GSH, SOD, catalase and GPx levels were observed in the OT group before and after RT compared to the RT group (Table 1) 9. Another study investigating the effect of ozone therapy on RT treatment showed that ozone, when used in combination with radiotherapy, can inhibit the growth of oesophageal cancer and increase sensitivity to treatment. In the study, rats with cancer were treated with a combination of radiation and ozone and it has been found that this combination significantly reduced tumour size and levels of related inflammatory biomolecules. Ozone affects some cellular signalling pathways, making tumour cells more sensitive to radiotherapy 10. Another RCT was conducted on the protective effect of OT against reproductive organ toxicity. after creating ovarian toxicity to 84 female mice with PM 2.5 (aerosol fine particulate matter), the mice were treated with vitamin C, vitamin E, acetyl salicylic acid and ozone. In the study design, acetyl salicylic acid, vitamin C and vitamin E were administered orally once a day for 3 weeks, and OT was administered by intraperitoneal injection once a day for 3 weeks. Results anti-Müllerian hormone (AMH), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were examined and evaluated by histopathological examination. ”PM 2.5 exposure increases the levels of IL-6 and TNF-a in ovarian tissue in mice and may lead to an inflammatory response, and ozone may also play a role in protecting against this exposure due to its anti-inflammatory effect, " it concluded. In addition, the AMH level was significantly higher in the ozone group compared to the control group, again, there was a decrease in the bax/ Bcl-2 and caspase protein ratios, which were involved in the apoptosis process, in the OT group compared to the control group. This shows us that OT makes a reduction in the apoptosis process. Histopathological examination showed that histopathological data such as ovarian damage, bleeding, vascular occlusion and follicular degeneration were normal in the ozone group compared to the control group (Table 1) 11. In another RCT conducted on cancer and ozone, 46 rats with tongue cancer were divided into 5 groups. Rats were made of tongue cancer with the substance 4NQO-Nitroquinoline 1-Oxide. 1. Group; cancer only (n:8), 2. Group: Cancer + RT (n: 10), 3. Group: cancer + ozone (rectal ozone) + RT (n:10), 4. Group: cancer + ozone (rectal ozone) (n:10), 5. Group: 4 Cancer-free group given physiological serum instead of NQO (n:8). Ozone application: 1 ml at a concentration of 15 mcg / ml, rectal 4 sessions, 5 days were performed. As a result of the study, RT and ozone were used together in the group with more significant results compared to the group that received only ozone and only RT. There were no cases of dysplasia and squamous cell cancer in the ozone + RT group (Table 1) .12 It was determined that ozone treatment on breast cancer cell lines in vitro caused an increase in pro-apoptotic genes and a decrease in the anti-apoptotic gene Bcl-2. In the study, cell viability decreased by 50% at the end of the 3rd day in breast cancer cells. This study indicated that ozone can be used as an antimetastasis procedure as well as an adjuvant in the treatment of cancer patients. 13 Another study investigated the effect of intravesical OT on non November invasive bladder cancer. In this study, 51 male rats were divided into 4 groups. 1. Group: 'Group with bladder cancer induced by n-methyl-n–nitroso urea (MNU). 2. Group: MNU+ bladder cancer + ozone (intravesical), 3. Group: isotonic serum intravesical only (placebo), 4. Group: only ozone was given intravesically. The results were evaluated by histopathological examination and tissue oxidant/ antioxidant levels (Table 1). When we looked at the results, there was a higher SOD value in the MNU + O3 group compared to the MNU group. Although the MNU + O3 group was not significant, it had a smaller number of high-grade lesions. This has also been evaluated as a promising result in the treatment of November non-muscle invasive bladder cancer by intravesical OT 14. In another RCT, the location of OT in peritoneal carcinomatous was investigated. 60 albino mice were made intraperitoneal carcinomatous. Then the mice were divided into 6 groups. 1. Group: OT (20mg/L- Intraperitoneal for 10 days), 2. Group: OT (40 mg/ L – 10 days- Intraperitoneal), 3. Group: RT only, 4. Group: OT (20mg/L- 10 days Intraperitoneal) + RT, 5. Group: OT (40 mg/ L – 10 days- Intraperitoneal) + RT, 6. Group: peritoneal carcinomatous + no treatment. Body weight change, abdominal circumference change and survival rates of mice were evaluated. The longest survival rate was found only in the groups with OT and receiving ozone + RT. The survival rate of all groups was higher than Group 6 (Table 1). There was a decrease in the abdominal circumference in the first and third groups. In contrast to this result, an increase in abdominal circumference measurements was observed in all other groups 15. Human papilloma was divided into 2 groups after 20 rabbit ear squamous cell cancers were performed at an RCT investigating OT in head and neck cancers caused by the virus. 1. Group: intraperitoneal ozone, 2. Group: intraperitoneal oxygen was administered. The difference between the groups was evaluated by white blood cell, CD3(+) tumor infiltrating lymphocytes (TIL), tumor volume (Table 1). As a result, it was concluded that intraperitoneal oxidative stress triggers an immune response to the tumor and may be effective in the treatment of squamous cell cancer 16. Another cancer study with HPV involved 40 mice. Mice made of HPV-related skin cancer. The mice were divided into 4 groups. 1. Group: HPV negative untreated group, 2. Group: HPV negative + OT, 3. Group: HPV positive without treatment, 4. Group: HPV positive + OT. The herb was given intraperitoneally. The skin samples of the groups were examined histopathologically (Table 1). As a result of this study, the rate of epithelial dysplasia was found to be lower in the HPV+ group receiving OT than in the HPV + untreated group (Table 1) 17. In an RCT on the effect of OT on lung cancer, 40 female rats were divided into 5 groups. 1. Group: Intraperitoneal saline solution was given. 2. Group: intraperitoneal saline + 6 hours 6 Gy ionizing radiation was given. 3. Group: intraperitoneal saline + 6 Gy ionizing radiation was given for 72 hours. 4. Group: Intarperitoneal ozone (0.7mg/kg) + 6 Gy ionizing radiation was given for 6 hours. 5. Group: Intraperitoneal ozone (0.7 mg/ kg) + 6 Gy ionizing radiation was given for 72 hours. The results were compared with serum TNF-α and IL-1β, lung tissue superoxide dizmutase (SOD) levels, lung malondialdehyde (MDA) levels (Table 1). In the study, it was shown that OT reduces serum TNF-α and IL-1β levels in rats, reduces lung tissue SOD activity and preserved pulmonary MDA levels. The results showed that intraperitoneal ozone provides protection against acute radiation damage in the rat lung 18. In a case report showing the effect of OT on non-small cell lung cancer, a 77-year-old patient with stage 3 lung adenocarcinoma was added to Gc protein-derived Macrophage activating factor (GcMAF), sonadynamic therapy and tumor treatment area therapy (TTF) treatments; major OT was added a total of 6 times a month, 3 times a week. The patient was followed for 15 months. The tumor has not expanded for 15 months, and many of the patient's symptoms have improved. As a result of the study, he suggests that combined therapy can be used to achieve better results for patients with cancer, with minimal toxicity and without negative effects on the immune system 19. Investigating the effect of OT on survival in squamous cell cancers, Schulz S and colleagues compared intraperitoneal OT survival rates and tumor clearance rates (TTC) after 90 days compared to intraperitoneal oxygen (placebo) group in a study of 59 rabbits with advanced ear squamous cell cancer (Table 1). 90-day survival and TTC rates among rabbits with advanced squamous cell cancer were found to be longer in the Decoction group compared to the placebo group 20. In a study investigating major OT in thyroid nodules, patients were divided into 2 groups. 1. Group: major OT + medical treatment (n: 17), 2. Group: medical treatment only (n: 41). Patients received levothyroxine or potassium iodide as medical treatment. 1 In the 6- and 12-month post-treatment results. a significant improvement in thyroid gland blood flow and the structure of thyroid tissue was observed in the group 21. In a study designing a microwave-controlled ozone release system, the system triggers cell death in tumor cells by producing reactive oxygen species, thereby making the immune system more effective against the tumor. The method, used in animal experiments, demonstrated a strong antitumor effect against TNBC when combined with PD-1 blockade, minimizing systemic toxicity. The study indicated that this innovative approach holds promise for improving immunotherapy, particularly in tumor types with low T-lymphocyte infiltration 22. Although the details of a study conducted in 1987 could not be reached, “21 women with progressive cervical cancer (Stage III, IV) were given OT in addition to conventional irradiation therapy. The effect of OT on humoral immunity in cancer patients has been investigated. After RT and OT, a small decrease in IgG, IgA and IGM was observed, but the statistical significance could not be evaluated." has been concluded in the form of 23. 31 male wistar-albino rats aged 1 month were used in an RCT on cryptoorchism and related possible testicular cancer. The groups are formed as follows: 1. Group: control/ non-intervention group, 2. Group: fake surgery (cryptorchidism), 3. Group: cryptorchidism + ozone, 4. Group: cryptorchidism + human chorionic gonadotropin (hCG) and 5. Group: Ozone + hCG. Surgical procedures were performed on all rats except the control group. All rats except the control group were used to create an experimental model of cryptorchidism, and the animals' left tests were surgically inserted into the abdomen. After surgery at the age of 1 month, 3, 4 and 5. intraperitoneal treatments were performed to the groups for 4 weeks. At the end of the study period, testicular atrophy index (TAI) and testicular sperm motility (TSM) were evaluated and biochemical, histopathological and immunohistochemical tests were performed (Table 1). TAI and TSM values were higher in the ozone group, hCG group and ozone + hCG group compared to the sham surgery group (p = 0.001). The TSM value in the ozone group was also significantly higher than that of the hCG group and the ozone + hCG group (Table 1) 24. In a case report conducted on patients with glioblastoma (GB), 5 patients were enrolled in the study. Grade 4 GB diagnoses of the patients were available. The patients were patients who underwent tumor surgery after CT and RT and had recurrence after surgery. Ozone application (5 ml per 40 µg / ml) was made to the patients around the tumor every 4 weeks. With the administration of the OT, a decrease in the tumor volume of the patients was observed from the firs session. In addition, the life expectancy of patients is longer than the expected life expectancy at GM it was long and had a survival of about 40 weeks (Table 1). In this study, it was emphasized that OT can be evaluated as a viable adjuvant therapy in oncological patients receiving radiochemotherapy 25. In a review evaluating the effect of ozone therapy on advanced gliomas, ozone therapy was considered as a potential treatment for advanced gliomas (HGG) and especially for glioblastoma, the most aggressive type of brain cancer. It has been reported that the combination of photon radiotherapy and ozone therapy may enhance the effects of radiation by improving oxygen conditions in the tumour microenvironment. This finding is particularly important for gliomas, which are hypoxic due to low oxygen levels and therefore more resistant to standard treatments such as radiation. The study suggests that ozone therapy may improve outcomes when used in combination with conventional glioma treatments with surgery, radiation and temozolomide (STUPP protocol)26. In a study evaluating the growth effect of ozone on human neuroblastoma cells SK ‐ N ‐ SH and SK ‐ N ‐ DZ (invitro), chemotherapeutic agents (cisplatin, gemcitabine and etoposide) and OT were applied separately and combined to neuroblastoma cells. The growth rate of SK ‐ N ‐ SH and SK ‐ N ‐ DZ cells and the level of free oxygen radicals (ROS) in the cells were examined. It has also been shown that OT induces the formation of ROS in SK-N-SH cells and inhibits cell growth in both SK‐N‐SH and SK‐N‐DZ cell lines (Table 1). In this study, it was concluded that “As a result, the combination of OT with cisplatin, gemcitabine and etoposide is more effective than the separate use of these drugs, OT increases the effectiveness of CT drugs” 27. In the study in which the effects of Oxygen-Ozone combination and Cannabidiol separately and together on human pancreatic cancer cell lines named PANC-1 and MiaPaCa-2 were investigated, the results were evaluated by analysing gene expression profiles, cytotoxicity, cell migration and cell death. Furthermore, the effects of combinations with the drugs GEM and PTX, which are widely used in the treatment of pancreatic cancer, were studied. Oxygen-ozone treatment and cannabidiol increased cell cytotoxicity and decreased cell viability in both cell lines. In addition, the combination of Cannabidiol and Oxygen-Ozone has been observed to further reduce cell viability when used in combination with chemotherapeutic drugs. In the study, it was stated that the combination of Cannabidiol and Oxygen-Ozone may be a potential treatment method in the treatment of pancreatic cancer28. Most of the studies conducted on OT people are skin ulcers and negros due to severe treatments such as CT and RT, as well as gastrointestinal tract ulcers/ bleeding, cystitis, bone lesions, cancer pains, and psychological problems such as insomnia, anxiety, depression that can be observed in oncology patients. OT, ozone cream, regional ozone diffusion method and systemic OT have been applied in studies on skin lesions such as ulcers and negrosis that develop after RT. In all studies, it was found that OT is effective in skin lesions 29-31. In a study, the effects of intracellular Criegee mechanism-based synergistic ozone therapy applied through oleogels on cancer were investigated. Researchers have developed ozone-loaded oleogels for tumour ozone therapy (O3-T) in a postoperative melanoma model. This treatment has shown synergistic effect when combined with chemotherapy and radiotherapy. Ozone therapy was effective by destroying tumour cells through the intracellular Criegee reaction and regulating the tumour microenvironment. It has also been observed to inhibit the growth of both primary and secondary tumours in in vivo experiments. In the study, it was stated that the results will inspire future studies for ozone therapy, especially in the treatment of postoperative skin cancer32. One of the most important side effects of RT is rectal bleeding. In an RCT conducted on this subject, the effect of OT on hemorrhagic radiation proctitis was investigated. Patients with persistent or severe rectal bleeding who did not respond to conventional treatment after prostate cancer treatment (RT) (n = 12) were OT-treated by rectal insufflation and / or topical application of ozonated oil. The severity of rectal bleeding was classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) rating system (Table 2). Table 2. The results of the common terminology criteria for undesirable events. After OT, there was a decrease in important measures such as blood transfusion requirements and the need for endoscopic procedures. In conclusion: "OT has been effective in radiation-induced rectal bleeding in prostate cancer patients without serious adverse side effects." Concluded 33. In addition, some studies have also reported that the application of OT with rectal insufflation is effective in rectal bleeding due to rectal malignancies, but further studies are required 34,35. In a study, an ozone-carrying liposome nanosystem (O3_PFD@Liposome) was developed to improve the effectiveness of radiotherapy. When used in combination with radiotherapy, this system promotes immunogenic cell death in tumour cells and shows synergistic effects with immune checkpoint inhibitors. The nanosystem increased the solubility of ozone in water, reducing oxygen deficiency in the tumour microenvironment and promoting hydroxyl radical production. As a result of the study, this combined treatment method effectively inhibits the growth of primary and secondary tumours and strengthens the anti-tumour immune response without causing serious side effects36. A study conducted in Spain showed that OT shortens the onset of CT and RT after oncological surgery 37. Ozone therapy applied before surgery has also been shown to reduce postoperative complications. In a study examining the effect of controlled ozone application after radiotherapy, it was shown that ozone treatment increased hydroxyproline concentrations in tissues, myeloperoxidase, a marker of oxidative damage, was significantly lower and had positive effects on anastomotic healing38. Another negative effect that can be seen in the treatment of cancer is skin fistula, which was done as a case study. Local ozone application has been tried in the skin ulcer formed in the port area attached to the patient during the breast cancer treatment process, and it has been found to give successful results 39. In a case representation, the use of ozonated water in a case of gastro-thoracic fistula following treatment of oesophageal squamous cell carcinoma is described. Fistula that could not be closed by surgical intervention or endoscopic treatment was complicated by severe multidrug-resistant bacterial infection. The patient was treated with drainage and local irrigation with ozonated water, and oral ozonated water was also given. This treatment was successful, the fistula healed and the infection was controlled. In this presentation, it was stated that ozonated water was an effective alternative treatment to control infection and heal fistula 40. The use of immunosuppressive drugs in the treatment of cancer increases the risk of secondary infection, which may have fatal consequences for the patient (Masaoka T, Ernst E). In a study conducted on this subject, OT was applied to patients with leukemia during treatment and it was shown that ozone reduces the risk of infection 41. One of the undesirable effects of CT is bone negrosis. In the studies conducted on this subject, there are studies showing that OT gives successful results in bone necrosis 42-44. In the treatment of gastroduodenal ulcers that can be seen during treatment or after surgery in cancer patients, as well as in pain that can be seen during and after treatment of cancer patients, OT has been found effective as an important supportive therapy 35, 45-49. Cystitis accompanied by treatment-resistant hematuria after RT is a common picture. Clavo B. and in a study conducted by his friends, they showed that intravesical ozone administration of 3 sessions per week was successful in the table of cystitis 50. In a study, the effects of ozone therapy on the chronic side effects of radiotherapy and chemotherapy in symptomatic cancer patients were investigated. 26 cancer patients were evaluated for health-related quality of life (HRQOL) and toxicity before and after ozone therapy. The results showed that ozone therapy significantly improved HRQOL and toxicity. Health status and all dimensions (mobility, self-care, daily activities, pain/discomfort and anxiety/depression) improved significantly according to the EQ-5D-5L questionnaire. In addition, their degree of toxicity has also decreased. The study indicated that ozone therapy is potentially beneficial in reducing the negative side effects of cancer treatment51. In a study examining the anticancer effects of ozone on liver cancer cells, Bel7402 and SMMC7721 cell lines were used, and it was found that ozone treatment inhibited cell proliferation and colony formation, stopped the G2/M phase of the cell cycle and reduced cell migration ability. Ozone treatment also increased reactive oxygen species (ROS) accumulation and decreased glutathione levels, which contributed to the suppression of the PI3K/AKT/NF-κB pathway. As a result of the study, ozone was found to have inhibitory effects on proliferation and migration in liver cancer cells52. Liver damage that may occur as a result of tumor and/ or treatment is a common complication (Parkhisenko luA). It has been shown that support with parenteral OT provides regression in liver function tests in cases of jaundice caused by liver problems that may occur after tumor and/ or treatment 53. In a study investigating the effectiveness and mechanisms of ozonised oils with high ozonide content in preventing cancer recurrence, it was reported that ozonised oils suppressed cell viability by triggering mitochondrial damage, intracellular calcium release and apoptosis in lung and glioblastoma cancer cells in in vitro experiments. As an in vivo experiment, a study on 115 cancer patients was presented, and it was reported that the survival rates of patients receiving ozonised oil therapy in addition to standard chemo/radiotherapy improved significantly. The study indicated that ozonated oils could be a potential innovation in complementary cancer therapy 54. Apart from the positive effects of ozone therapy, there are still controversies about its effect on the growth of cancer cells. A study investigated the effects of low concentrations of ozone on the motility and proliferation of cancer cells in vitro. The therapeutic potential of low ozone concentrations has been reported to be based on increasing nuclear translocation of Nrf2, inducing transcription of genes driven by Antioxidant Response Elements (ARE) and cytoprotective responses. In this study, HeLa cells were exposed to low ozone concentrations and as a result, no changes in cell morphology, motility and proliferation were observed. These findings support the view that low ozone concentrations do not affect tumour cell growth and metastasis55.

Cancer disease and its treatment are difficult situations to overcome, both socially and economically, for individuals and societies. While there is insufficient evidence for OT to be used as the primary drug in the treatment of cancer, many cancer patients experience additional problems such as pain, infections, gastrointestinal issues, and psychological problems due to conventional treatments or their illnesses. OT is one of the most scientifically proven treatments with standardization in other traditional and complementary medicine practices, and it can be recommended to these patients as a supportive treatment.

Table 1: Studies on ozone therapy used in cancer treatment

RT: Radiotherapy, CT: Chemotherapy, OT: Ozone therapy, IP: intraperitoneal, IT: Intratumoral, IV: Intravesical, R: Rectal, OHT: Autohemotransfusion PM25: aerosol fine particulate matter, AMH: Antimiullerian hormone, TNF- α: Tumor negative factor α, 4NQO: Nitroquinoline 1-Oxide substance), MDA: malondialdehyde, SOD: Superoxide dizmutase. GSH: Glutathione, CAT: CatalasMNU: ’n-methyl-n–nitroso urea, HPV: Human papilloma virus, TAI: Testicular atrophy index, TSM: Testicular sperm motility, hCG: Human chorionic gonodotropin, ROS: Free oxygen radicals.

The mechanism of action of ozone begins with the rapid oxidation of its components. Oxidized molecules and the specific antioxidant produced are the active components of ozone 8, 56. In the ozone vascular bed, malonylated aldehyde leads to increased lipid peroxidation, activation of hexose monophosphate shunt, as well as increased production of 2,3-diphosphoglycerate in erythrocytes 57, 58. This causes the oxyhemoglobin separation curve to shift to the right, resulting in an increase in oxygen release to the tissues. Tue. A pH decrease in erythrocytes shifts the oxyhemoglobin separation curve to the right (Bohr effect) without changing the 2,3-diphosphoglycerate 59. It also causes a load change in the red cell membranes, an improvement in membrane elasticity and a decrease in blood viscosity and resistance 60. On the other hand, adenosine, prostaglandins and especially nitric oxide release affect microcirculation and may cause a decrease in vascular resistance. Tuesday, the release of adenosine, prostaglandins, and nitric oxide. Ozone induces the production of nitric oxide by vascular endothelial cells and thus produces vasodilation at the microcirculatory level. These two effects reduce peripheral vascular resistance and, as a result, cause an increase in blood flow 61. On the other hand, when we look at the studies showing that ozone can be used in the treatment of cancer, it is stated that hypoxia and ischemia in cancer tissue negatively affect the treatment of CT and RT, and OT increases the effect of CT and RT by reducing this hypoxia and ischemia with the effects mentioned above 3, 8, 62-66. At what stage of tumor treatment should we use ozone? when we look at the answer to the question; In a study conducted by Aydogdu I and his colleagues on this subject, OT in testicular damage due to RT was given to one group before RT and to another group during RT. It was concluded that OT had a positive effect on testicular damage in both groups 9. This leads to the conclusion that OT can also be given prophylactically before starting cancer treatment. Should we reduce the CT dose of patients in the light of studies showing that OT is an adjuvant treatment for cancer? The answer to this question was given by Kuroda K in 2018 and we see it in the study that his friends conducted on mice with girth cancer. In the study, the cisplatin dose was reduced with OT, but the most effective effect was seen in the ideal cisplatin dose + OT group 7. As a result, it turns out that OT contributes to a more effective result of CT therapy rather than reducing the CT dose. However, it is still clear that there is a need for more RCTs in this regard. In a study conducted in 2015, which emphasized the importance of OT dose in cancer, different doses of ozone were added to RT in mice with peritoneal carcinomatous. The survival rate was highest in the high-dose ozone + RT group 15. Although it turns out that high doses of ozone further increase the effectiveness of RT, much more advanced RCTs are needed in this regard. Another study that shows that OT is a good supportive treatment for cancer is on infections, one of the most feared side effects associated with anticancer drugs. In a study conducted in Japan on this subject, Masaoka T. and his colleagues had shown that major OT reduces the risk of secondary infections in patients with leukemia 41. In addition, in a study investigating the effect of OT on the fatigue and burnout table caused by cancer disease and treatment, patients with 50 different types of cancer (15 breast cancer, 12 lung cancer, 11 colon cancer, 5 kidney cancer, 3 prostate cancer, 2 melanoma and 2 hepatocellular carcinoma) were enrolled in the study. 10 of the patients had completed their cancer treatment earlier. In the study, patients were given auto hemotransfusion OT 2 times a week for a month and 2 times a month for subsequent months. As a result of the study, it was shown that OT can be a valid treatment for fatigue in both patients undergoing cancer treatment and patients undergoing palliative therapy 67. In a study examining the efficacy of oxygen-ozone autohemotherapy in breast cancer patients with weakness, fatigue and musculoskeletal pain during aromatase inhibitor therapy, 6 female patients with an average age of 64 years had a 66% reduction in pain (NRS: 9.43 to 2.36, p<0.001) and a 66.26% reduction in fatigue. Pain and fatigue disappeared one month after treatment and the healthy, pain-free condition persisted for months. In the study, it was reported that oxygen-ozone therapy was effective in reducing anti-aromatase-induced symptoms in breast cancer patients 68. There are also many studies showing that local and systemic OT is effective in the treatment of rectal bleeding, gastroduodenal ulcers, osteonegrosis, skin negrosis, skin fistula, which are side effects of CT and RT In a literature study on this subject, ozone therapy has been shown to be effective in reducing chemotherapy-induced side effects, increasing oxygen tension, normalising blood flow, restoring blood lymphocytes faster and reducing fatigue symptoms in patients with breast cancer 29–31,33–35,37,39,42–46,50,69. Oncological surgery is one of the inevitable treatments for many cancer patients. CT and/ or RT are usually given again after these treatments 70. Wound healing and the general well-being of the patient are also important when resuming CT and RT after oncological surgery. G in Spain in 1999. In a study conducted by Rovira et al., it was shown that OT reduces the time to start CT and RT after oncological surgery. This leads to the conclusion that starting anticancer treatment early will lead to more effective results 37. In a study, it was reported that ozone therapy showed significant improvements in anxiety and depression in patients with advanced chronic nononcological diseases with symptoms resistant to cancer treatment71.

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