This report, as a continuation of 8-years research on the problem of noninvasive clinical fluorescence diagnostics efficiency, discusses a hypothesis of influence of a chronic hypoxia state in soft alive tissues on the intensity of a laser-induced endogenous porphyrins' autofluorescence in a red region of optical spectra. Earlier this hypothesis was proposed on the basis of analysis of fluorescence activity for erosive-ulcerative impairments of the upper part of a gastrointestinal tract (SPIE Proc., vol. 4613, 2002. -p.286-294). Today the hypothesis additionally is confirmed by means of observation after patients with another illness and by means of analysis of some well-known literature data. An authors' methodology of clinical trails to verify the hypothesis using an up-to-date noninvasive fluorescence diagnostic technique is presented as well. Both theoretical reasons and all new clinical data show that the chronic hypoxia state can be one of the major factors of appearance of a large and abnormal laser-induced autofluorescent signal from biotissues in the spectrum range 600-800 nm, which is associated with abnormally high accumulation of endogenous porphyrins in the tissues. So, the noninvasive autofluorescent diagnostic technique could be a powerful tool to estimate in vivo a chronic hypoxia condition in soft biotissues. For that purpose a classification of chronic hypoxia levels versus in vivo autofluorescence contrast coefficients in tissues is proposed as well.

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The laser "in vivo" autofluorescence diagnostics is now widely studied and applied in different areas of medicine, such as an oncology, dermatology, etc. Recently we have reported of created new professional multiwave laser diagnostic system (MLDS) for this purpose under the international scientific research and development project #1001 supported by the International Scientific and Technology Center. This presentation lights some results of application of the MLDS in a real clinical practice at Moscow Regional Research and Clinical Institute "MONIKI", Department of Radiology. With the use of MLDS we investigated a skin and oral cavity cancer endogenous fluorescence before, during and after standard radiotherapy treatment. A statistical analysis showed that the best radiotherapy result was achieved for the patients with a small initial porfirines' autofluorescence and a great initial flavines' one from irradiated tumor tissues. It was shown that each radiotherapy procedure has an influen ce on a tissues' autofluorescence intensity. The tendencies in porfirines' fluorescence during a treatment course can be an additional prognostic factor for the prediction of the efficacy of a radiotherapy treatment. Moreover, it was estimated that a number of non-cancerous skin disease has a typical "cancer" initial autofluorescence, that makes it difficult to distinguish them one from another with the use of only the fluorescence diagnostics, but opens the way to investigate the non-cancerous tissues diseases with the help of tissues endogenous fluorescence phenomenon.

Based on an analysis of various clinical data, the assumption was recently expressed that the often observed in vivo increased fluorescence of endogenous porphyrins in living biological tissues is a consequence of the status of chronic hypoxia in the tissues. Starting from this, this article discusses the accuracy, reproducibility, and information content of methods of in vivo laser fluorescence diagnosis ͑LFD͒ in actual clinical practice. It is shown that, despite the random error of single measurements in LFD of 30-40% established earlier, the accuracy and reliability can reach a fairly high level when the results of the diagnosis are interpreted. The formal random scatter in the results of single measurements is largely determined not by the instrumental error but by the methodological error and by the living and changeable character of the object of diagnosis, especially at the level of the blood-microcirculation system.

Temperature fields on the surface of skin and the parameters of the microcirculation of blood in the skin accompanying various procedures of low-intensity laser therapy have been investigated by means of an IRTIS-2000ME digital thermograph and a LAKK-M spectrophotometric diagnostic complex. It is shown that changes of the parameters of the microcirculation of the blood in the skin accompanying both surface laser procedures and intravenous laser irradiation of the blood, if they were observed, were always accompanied by changes of the temperature of the skin surface.