Brazilian scientists have developed a technique for diagnosing cancer based on the analysis of saliva and urine samples. The method turns the samples into steam, from which volatile compounds are extracted to identify alterations that serve as “fingerprints” of the disease.
Although the technique is experimental, the results obtained in the study open perspectives for the future use of a low-cost, non-invasive alternative for diagnosing different types of tumors. The results were published in scientific journal Journal of Breath Research.
“To diagnose cancer, doctors use several tests, such as mammography, CT scan, MRI, endoscopy, colonoscopy, blood tests and biopsy. These methods are safe and effective. However, these procedures are often invasive, laborious, involve considerable costs and require highly qualified professionals,” said biochemical pharmacist Bruno Ruiz Brandão da Costa, first author of the article, in a statement.
The specialist defends the creation of accessible, fast and non-invasive diagnostic techniques as a critical demand in the health area. Costa explains that volatile organic compounds (VOCs) are chemical substances naturally produced by the human body.
“However, in cases of diseases such as cancer, metabolic changes occur that can generate new VOCs or modify the concentration of those already present in the body. These changes in the profile can be detected through chemical analyses”, he says. “In this sense, the main objective of our research was to compare the profile of VOCs present in the oral fluid and urine of healthy people and cancer patients. With this, we seek to identify whether there is a significant difference between the profile of these substances in the two groups, which could be useful in the diagnosis of the disease”, he continues.
The researchers collected saliva and urine samples from healthy people and from patients with head and neck and gastrointestinal cancer from the outpatient clinics in the Clinical Oncology area of the Hospital das Clínicas of the Faculty of Medicine of Ribeirão Preto at USP. The analyzes were carried out at the Laboratory of Forensic Toxicological Analysis of the Chemistry Department of the institution.
For analysis, the material was placed in a closed flask, heated and shaken. As the substances of interest are volatile, they passed into the vapor phase, also called the headspace, which was then analyzed.
“These substances present in the headspace were then injected into gas chromatography equipment with an ionization detector (GC-FID), which performs the separation of these compounds”, says Costa. “After separation, the compounds are detected and generate an analytical signal that we call a ‘peak’. The set of peaks present throughout the analysis is called a ‘chromatogram’”.
What is the “fingerprint” of cancer
The scientists compared the profiles of the samples using statistical analyses. The investigation made it possible to verify whether there were significant differences between the samples of healthy people and patients with cancer.
“To compare the chromatographic profiles of the samples, we used statistical analyzes to verify whether there are significant differences between the samples of healthy people and people with cancer, thus identifying the ‘signatures of cancer’”, says the researcher.
The expert adds that the substances present in the samples were not identified, which would require more expensive and specific equipment. “The differentiation was made exclusively by the different profiles of the peaks present in the chromatogram, which is also called a fingerprint, or a ‘fingerprint’ of the cancer”, he says.
The research evaluated the effectiveness of the diagnosis both with data obtained only from a biological material, and with both donated samples, called by specialists as “hybrid analysis”.
The individual models that showed the best results in terms of sensitivity and specificity were the head and neck cancer in urine, with 84.8% and 82.3%, and the gastrointestinal cancer in saliva, with 78.6% and 87.5%.
“With regard to the hybrid models, for head and neck cancer, we obtained 75.5% sensitivity and 88.3% specificity. As for gastrointestinal cancer, the rates were 69.8% and 87%, ”he said.
Several studies seek to relate the diagnosis of cancer to the analysis of volatile compounds. “Our results are promising, however, the number of volunteers who participated in the research was relatively small. It is necessary to continue the research with a much larger number of participants before thinking about using the method in health services. But I believe, and I hope, that one day this can happen”, evaluates the professor.
(With information from Júlio Bernardes, from Jornal da USP)
Source: CNN Brasil
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