Optical diagnosis of skin cancer

Samara scientists have increased the accuracy of early diagnosis of skin neoplasms to 97%

SamSMU Press Service

A team of scientists from the Samara National Research University named after Academician S.P. Korolev and Samara State Medical University (SamSMU), as well as clinical specialists from the Samara Regional Oncological Dispensary (SOCOD) tested a new method for early diagnosis of skin cancer using an original set of three new devices.

The effectiveness of cancer treatment directly depends on the timeliness of their detection. For example, for melanoma, the most aggressive form of a skin tumor detected at the first stage, the five–year survival rate after treatment is 98%, and does not exceed 15% when diagnosed at the fourth stage. The methods created by a team of Samara scientists have made it possible to increase the effectiveness of active and early diagnosis of skin neoplasms up to 97%, while the accuracy of a conventional, standard clinical study does not exceed 50-60%.

The research results are presented in the article Combined Raman and autofluorescence ex vivo diagnostics of skin cancer in near-infrared and visible regions, which was published by one of the most authoritative journals devoted to the use of modern optical technology for biomedical research - Journal of Biomedical Optics. The methodology of Samara scientists is based on a system of spectroscopic analysis of problem areas of the skin developed at the Department of Laser and Biotechnical Systems of Samara University (Head Professor Valery Zakharov) with subsequent medical interpretation of the data obtained, proposed by the Department of Oncology of Samara State Medical University under the guidance of Professor Sergey Kozlov. As Professor Zakharov explained, the developed spectral analysis system allows to simultaneously register the parameters of the patient's skin in many spectral ranges, which makes it possible to notice pathological changes at the cellular level, since diseased cells differ from healthy ones in their spectrum.

For mass examinations, this method is the best possible: it not only allows you to diagnose pathology accurately and quickly enough, but also does not require the use of additional consumables and reagents, as well as in a number of observations to do without the use of invasive methods to confirm the diagnosis. "So, for example, if a skin melanoma is suspected, an incorrect tumor biopsy increases the risk of metastasis," added Alexander Moryatov, curator of the project, associate professor of the Department of Oncology at SamSMU. "In any case, after examination of the patient and surgical treatment, we finally confirm the diagnosis morphologically."

For diagnostics, scientists use three devices. The first is an experimental setup for measuring raman scattering, it studies the spectral characteristics of neoplasms, primarily skin melanoma. According to Sergey Kozlov, this device is suitable for accurately determining the nature of a malignant tumor, allowing for quick and safe differential diagnosis between melanoma and other forms of skin tumors. "This installation can be installed in a regular district polyclinic," the professor said.

The second device, a dermatoscope, gives a visual picture of the tumor with the maximum approximation to its surface and allows you to see and record the characteristic signs of this disease in real time for analysis. According to Sergey Kozlov, this device compares favorably with similar ones with a user-friendly interface, the ability to analyze in polarized light mode, and also with the help of special illumination to study the features of the accumulation of melanin, hemoglobin, the structure of capillary networks in the studied areas of the skin.

The third, a hyperspectral camera, allows you to take several dozen images in different spectra with high accuracy in a short time (different optical characteristics are characteristic of different skin neoplasms).

All three devices are a joint development of scientists from Samara University, SamSMU and SOCOD, and they are aimed at a comparative study of the optical characteristics of healthy and pathologically altered tissues, in which the analysis of various types of neoplasms is based on a joint interpretation of their spectra obtained using completely safe technologies and laser radiation sources with different wavelengths.

We are talking about two types of spectrum analysis, the nature of which depends on the biochemical composition of the tissue under study – the raman spectrum (RAMAN) and the autofluorescence spectrum (AF).

Raman scattering (Raman effect) is inelastic scattering of optical radiation on molecules of a substance, accompanied by a noticeable change in the frequency of radiation. Spectral lines appear in the spectrum of scattered radiation that are not present in the spectrum of primary (exciting) light. The number and location of the lines that appear is determined by the molecular structure of the substance. The principle of CR for cancer research is based on the fact that the development of a tumor is accompanied by chemical and structural changes in skin tissues at the molecular level. These changes are reflected in the Raman spectra, which are unique for each molecular compound.

The method of autofluorescence analysis is based on the fact that biological molecules are able to re-emit part of the absorbed light. The absorbed energy is released in the form of light having a different wavelength. The described phenomenon is called autofluorescence, since it does not involve substances supplied from the outside.

 "Such "double" spectroscopy allows, as our experiments show, to obtain information about the structure of tissues, on the basis of which it is possible to very accurately identify various types of skin tumors," says Ivan Bratchenko, associate professor of the Department of Laser and Biotechnical Systems at Samara University. All three devices work at the Department of Oncology of the Samara State Medical University, the clinical base of the Samara Regional Clinical Oncology Dispensary and have been used for several months in the examination of patients by oncologists. More than 400 people have already been examined with this equipment. "The results obtained give reason to hope that we are approaching diagnostic accuracy comparable to morphological examination," Alexander Moryatov noted. According to Sergey Kozlov, diagnostic devices have shown high resolution and may eventually enter the medical equipment market: "We have few competitors in Russia and abroad, but the results obtained are better."

Samara scientists associate the prospects of their research on the diagnosis of skin neoplasms with an increase in its accuracy due to the complication of the mathematical analysis of spectral data. Their future plans are to integrate a complex of three devices with fiber optics in order to use them already for the diagnosis of tumors of internal localization (gastrointestinal tract, lungs, etc.), while maintaining the same human–safe principle of research - spectral analysis of tumors.

Portal "Eternal youth" http://vechnayamolodost.ru  22.05.2017