Introduction. Gastric cancer (GC) remains a disease with an ominous forecast, for this reason, is essential the accurate management of gastric precancerous lesions (GPL): atrophic gastritis, intestinal metaplasia and gastric dysplasia. Multiple factors, including H.pylori, intestinal microbes, genetics, environmental factors living habits and diet, contribute directly and are associated with increased risk to develop GPL and GC. A recent prospective study demonstrated that 11 essential lipids including eight phospholipids and 3 free fatty acids are negatively related to the risk of GPL progression and that the characteristics of lipidomic may be associated with the risk of gastric disease progression and GC. The occurrence and development of GC tumors will be impacted by the phospholipid content of membrane fluidity and signal transduction. Oxygen-ozone (O2-O3) therapy has shown promising potential in managing chronic pathologies. The mechanism behind these benefits involves ozone's ability to modulate oxidative stress and enhance mitochondrial function. Moreover, ozone therapy is noted for its immunomodulatory effects, reducing pro-inflammatory cytokines and thereby potentially mitigating the chronic inflammatory state seen in gastric precancerous lesions. It disrupts bacterial wall proteins, lipoproteins, lipids, and glycoproteins. Ozone is a powerful oxidizing and lipolytic agent.
The objective of the present study was to evaluate the effectiveness and safety of ozone therapy on metabolic changes in patients with precancerous gastric lesions and to evaluate a proposed ozone therapy protocol treatment.
Material and methods. The study included 80 patients with GPL, 55 males and 25 females. Their age ranged between 44 and 69 years. Investigations including CBC, liver function tests, PCR, lipidogram, protein signatures and upper endoscopy, abdominal ultrasonography which were done before and 12 weeks, 24 weeks after starting treatment with ozone. The patients received combined treatment of major blood ozonation and rectal insufflation, ozonated bidistilated water and oil. Investigations were repeated after 8 and 24 weeks of treatment. General health and daily activity were observed. The study was approved by the Ethics Committee (approval No. 7, 03.2024) of the Nicolae Testemitanu SUMPh, Republic of Moldova. All participants provided written informed consent.
Results. It was found that following eight weeks of ozone therapy, the lipidogram value decreased in 58,5% of cases (p<0.001). Following 24 weeks of ozone therapy, there was further decrease of the lipidogram value that reached 83% of cases (p<0.001). Some proteins, namely MIF-2 and HPX, were further significantly associated with the risk of gastric lesion progression. After eight weeks of ozone therapy, the abnormal enzyme levels were back to normal in 45% of cases (p<0.013) for the GOT enzyme, and were back to normal in 60 % of cases (p<0.001) for the GPT enzyme. Following also the same period of therapy, the abnormal albumin parameters (normal value ≥3.5 mg %) were back to normal in 38% of cases (p<0.03).
Conclusions. Oxygen-ozone therapy shows significant promise treatment for metabolic changes in patients with precancerous gastric lesions, offering potential benefits such as reduced lipidogram value, improved liver function and enhanced patient quality of life. This decrease was evident after 8 weeks and further decline following another 24 weeks of ozone therapy.
Key words: Oxygen-ozone therapy, gastric precancerous lesions, gastric cancer, major blood ozonation, rectal insufflation.

The analysis of the correlation between the severity of gastric mucosal damage in chronic atrophic gastritis, determined endoscopically, and the stage of gastric mucosal atrophy and intestinal metaplasia, established according to OLGA and OLGIM staging systems, found that with the increase in the severity of chronic atrophic gastritis, the severity of the stages of the OLGA system and the OLGIM system increases. There is a direct, moderate and statistically significant correlation between forms of chronic atrophic gastritis and OLGA stages (ρ = 0.6, p <0.001), a direct, weak and statistically significant correlation between forms of chronic atrophic gastritis and OLGIM stages (ρ = 0.3, p <0.001).
A statistically significant and significant reduction of PG-I and PGR was determined simultaneously with the increase of the OLGA and OLGIM systems stages. The OLGA and OLGIM staging systems classify patients with chronic atrophic gastritis into stages with a high risk of developing gastric cancer, they are the most reliable and powerful systems that allow the recognition of the patient with a higher risk of developing gastric cancer, but their implementation is limited.
Conclusions: The implementation of OLGA and OLGIM systems for the classification and approach of chronic gastritis in medical practice is necessary to minimize the incidence and mortality rates caused by gastric cancer - a condition with an increased frequency. By applying these stratification systems for chronic atrophic gastritis, patients could benefit from appropriate treatment started in a premalignant stage.