N. Altman (1995) summarizing the available experimental and clinical experience of world practice of ozone therapy in his book "Oxygen healing therapies" wrote that ozone has been used in the oncology for about ten years.
The works dedicated to investigations into the action of ozone in malignant tumors were made by the scientists from Germany, Cuba, the USA, Italy, Switzerland and have been recently continued in Russia.
The foreign researches based their attempts at using ozone in the oncology on two discoveries.
The first discovery was made by O. Warburg (1966, Germany) that the key reason for development of tumor is oxygen deficiency on the cellular level.
The second discovery made by J. Varro (1974, Germany) showed intolerance of peroxides by tumor cells. In this connection there was made a supposition that ozone and hydrogen peroxide can affect metabolism of cancer cells. However, the works of J. Varro as well as the results of the earlier investigations made by the Russian scientists A.I. Zhuravleva, B.N. Tarusova (1962) that the content of peroxides in tumors is decreased as compared with normal tissues were not put to use in clinical oncology.
In 1980 F. Sweet et al. furnished proofs about a tumor-inhibitory effect of ozone in vitro. The investigations into the influence of certain ozone concentrations on the development of cultures of tumor cells received from malignant tumors of lung, mammary gland and uterus have established the suppression of neoplasma growth in 90% of cases. At the same time, it has been pointed out to a slight ability of tumor cells to compensate the oxidative stress induced by ozone in comparison with normal cells (Sweet, 1980). M. Arnan, L. DeVries (1983) investigated the influence of ozone on carcinoma inoculated to mice. The results of that experiment showed that the animals exposed to ozone lived by 30-40 days longer that the animals of control group. H. Karlic et al. (1987) established the selective suppression of tumor cell growth of ovarian carcinoma, ovarian adenocarcenoma and endometrial carcinoma. The similar results were demonstrated by K. Zanker and Krozek (1989).
In the conditions of normal cell respiration reactive-inert molecular oxygen converts to active metastable form only through enzyme-substrate complexes of electronic-transport chain of mitochondrions. In cancer cell this enzymatic chain is inactivated and destroyed. The use of ozone results in the formation of active oxygen metabolites that can react with hydrogen substrate and put into action the disturbed end oxidation of tumor cell thereby activating the respiration through the substituted mechanism as the protein-containing enzymes cannot be substituted. Thus, ozone provides an anti-tumor effect (N. Altman, 1995).
As discussed earlier, the growth of induced and inoculated tumors is associated with aggravation of oxygen supply, tissue hypoxia, and the pharmaceutical agents for treatment and prevention of hypoxic conditions in different diseases are mostly focused on the improvement of oxygen transportation to the tissues. In this connection the antihypoxic effect of ozone allows making a supposition that ozone can be also used as electron-acceptor compound - radiosensibilizator of hypoxic tumor cells. So, in cultures of skin cancer cells through ozone in vitro it came to sensibilization to radiation. Zanker at al. proved a synergetic effect of ozone and chemotherapeutic preparation 5-fluorine-urazila on cell cultures of large intestine cancer and mammary gland cancer.
At the same time, the use of ozone in oncology is restricted as in the most of cases it has been used empirically without rational basis and appropriate methods of control. It is known that the increased concentration of ozone in air contributes to pulmonary toxicity (V. Bocci, 1997). This problem was subject of several works, one of which showed an insignificant statistically unreliable increase in pulmonary tumors in mice of strain A/J that allowed making a conclusion that ozone is not a carcinogen for this strain (Witschi et al., 1999). At the same time, there are some investigations pointing out to inefficiency of ozone introduced intravenously in case of Erlich's carcinoma and sarcoma-180 or establishing an increase in pulmonary metastasis in mice with fibrosarcoma NR-FS (Kobayashi et al., 1987). The availability of such contradictory data can be explained by the fact that ozone therapy is dose-related and requires careful selection of conditions when ozone therapy is reasonable for use.
However, analyzing the mechanisms of the known anti-tumor physical-chemical methods we have formed an opinion that they all are focused on changing oxygen, free-radical homeostasis. From our point of view, ozone therapy (in particular, in the form of ozonated physiological saline) is the most physiological, effective and accessible method allowing influencing free-radical processes.
A very interesting investigation was conducted by the scientists from the Tcherkasskiy Engineering Institute G.S.Stolyarenko, V.N.Vyazovik and from the oncological health center M.T.Shaposhnikova, A.V.Gromiko. In the experiments in vitro they found such conditions (selection of ozone solvents, saturation time of solution by oxidant) when it was possible to observe lysis, cell pyknosis, numerous destruction of nuclear substance of tumor cells. The authors pointed out that the observed processes are similar to radiation as in the zone of tumors in liquid phase under exposure to radiation it also comes to synthesis of oxygen-containing oxidants or active oxygen forms. But in case of ozone-radical chemodestruction there is no burn, necrosis of normal cells (along the line of radiation) and apparently no influence due to effect of high-frequency fluctuations. The specialists called this process "mild radiation" (G.S. Stolyarenko, 2001).
Exactly thanks to the above-mentioned investigations we believe that ozone should occupy its own deserving niche in the complex treatment of malignant tumors.
Results of Experimental Investigations
A success of each therapeutic method based on the use of physical factors is defined by knowledge of the nature of disturbances on which these factors are focusing, on the one hand, and the mechanisms of their biological action, on the other hand.
Since in the metabolism of malignant tumor cells dominance belongs to the glycolysis, a phylogenetically older process than oxidation, tumor represents an original return to the earlier evolution level of development, a primitive and stable form of existence. In this connection it is logical to suppose that the creation of "evolution leap" - artificial oxidant environment of tumor - can contribute to disorganization of primitive anaerobic metabolism of neoplasma. The disturbance of free-radical balance at presence of tumor is manifested as the antioxidant activity of tumor tissue, on the one hand, and exhaustion of the antioxidant defense of the organism-tumor carrier, on the other hand.
It is considered that many anti-tumor methods can be divided into two groups. The methods of one group are focused on decreasing the level of free-radical oxidation. On the contrary, the therapeutic methods of the other group are somewhat connected with further intensification of free-radical oxidation in tumor cells.
A many-stage work on studying possible use of ozone in neoplasia "in vitro" has been made in the Central Scientific Research Laboratory of the Nizhny Novgorod Medical Academy (Russia) commencing 1994.
The first stage covered the experiment on the modeled systems of sarcoma-45 (not-metastasizing strain) and Pliss' lymphosarcoma (metastasizing strain). For local intensification of oxidative reactions in tumor tissue ozone was used in the form of ozonated physiological saline by methods of intra- and paratumoral administration. It is important to add that the use of ozonated physiological saline was started just after the transplanted tumor has reached a size of 1 cm in diameter, on the 14th day after inoculation when self-rejection of tumor tissue is already impossible. This is the important condition to investigate the effect of ozonated physiological saline. By the way, the experiment presented at the 2nd International Symposium on Ozone Applications (Cuba, 1997) was conducted incorrectly. The authors made a report that rectal application of ozone is able not only to stop the growth of tumor cell colonies, but also leads to complete resorption of tumor tissues of strain: RL-67, L-1210, LP-388, S-37 (Y. Rodriguez, 1997). However, the use of ozone was started after first 24 hours from tumor transplantation when there were no proofs about its transplantability in the organism of animal-recipient. Even if we would ignore this remark and consider that the transplanted cells were vital, the anti-tumor effect of ozone as reported by the authors is the effect in vitro.
It has been established that the local intra- and paratumoral introduction of ozone in the form of ozonated physiological saline creates a free-radical blockade of tumor, destroys its antioxidant defense, and as a result the intensified free-radical oxidation affects tumor considerably increasing the volume of necrotized tissue. That results primarily in restoration of prooxidant-antioxidant balance of the organism-tumor carrier.
As criterion of efficiency of any anticancerogenic method is considered prolongation of lifetime of experimental animals. This parameter for rats with sarcoma-45 was 27% and 30% for rats with Pliss' lymphosarcoma.
The second stage of the investigation was focused on studying a possible systemic effect of ozone introduced by parenteral methods and determination of the most effective concentration of ozone bubbled into the physiological solution for parenteral use. As criterion of efficiency serves a decrease in tumor diameter and at the same time a minimum disturbing effect of ozone on the integral organism. The experiments were conducted using ozonated physiological saline bubbled with ozone concentrations in gas mixture of 100, 400, 900 mcg/L. The use of ozonated physiological saline was started on reaching a tumor size of 2 cm in diameter. The appropriate ozone concentration was determined - 400 mcg/L - and used on the next stage of the investigation to study the combined effect of ozone and ionizing radiation. The mechanism of action of ionizing radiation (dominant in the anti-tumor therapy) is connected with the processes including free-radical reactions.
Ozone modifies the action of ionizing radiation through the oxygen effect. It increases radiosensitivity of tumor by means of its artificial oxygenation (overcome of radioresistance of hypoxic tumor cells).
Ozone used before the radiation increases a therapeutic interval between the tumor and normal tissue that allows reducing the radiation dosage used and therefore decrease load on health tissues, mobilize antioxidant resources, restore the organism's own defense properties. Thus, ozone in high concentrations used by local methods produces an anticancerogenic effect, and in combination with ionizing radiation increases the efficiency of anti-tumor therapy. However, the "triumph" of ozone was disturbed by the following important fact.
It was established that ozone concentration of 900 mcg/L used by parenteral method contributes to resorption of primary tumor knot, but results in metastasis of lymphosarcoma in 17% of animals.
Although ozonated physiological saline leads to destruction of tumor, it also induces a powerful free-radical attack exceeding the organism's antioxidant potential and thereby creates cancerophilic conditions for normal tissues that leads to metastasis of tumor.
This discovery was confirmed both in the experimental works of foreign scientists and theoretical works of Russian scientists. Actually the stable prooxidant condition and the excessive level of lipid peroxidation in the cell create a "cancerogenic" situation inducing blastomatous transformation.
Anyone should know this and remember before using ozone in the oncology as well as that ozone therapy is dose-related and requires careful selection of conditions when ozone therapy is reasonable for use.
All anti-tumor physical-chemical methods are focused on changing oxygen, free-radical homeostasis.
Ozone therapy (in particular, in the form of ozonated physiological saline) is the most physiological, effective and accessible method allowing influencing free-radical processes. Ozone in the complex treatment of malignant tumors must occupy its own deserving niche.
(S.P.Aljohina, T.G.Tscherbatyuk "Ozone therapy: clinical and experimental aspects" - Nizhny Novgorod, 2003)