Researchers from the University of Alicante (UA) and Alicante General University Hospital's Institute for Health and Biomedical Research (ISABIAL) have developed a new non-invasive method for diagnosing and preventing colorectal cancer (CRC) through the analysis of volatile organic compounds in stool samples. It is worth noting that over the course of this project the team has detected three biomarkers related to this tumour.
Spain currently has a high incidence of colorectal cancer, with roughly 25,000 cases diagnosed every year. It is estimated that the average person has a 5% chance of developing this tumour. In fact, it is the second most lethal cancer in Spain, with a higher incidence rate for men than for women.
This innovative system, for which a patent application is pending, employs a relatively recent technology created by the UA Research Group in Atomic and Mass Spectroscopy and Analytical Chemistry in Extreme Conditions.
This technology can be used to analyse the contaminants in the water of volatile compounds by means of magnets and magnetic graphene oxide.
The question we asked ourselves when we started this research four or five years ago was whether a person with colorectal cancer or colorectal polyps could generate a volatile compound that could be detected using our powerful chemical analysis instruments."
Antonio Canals, Head of Research Group. University of Alicante
The scientists found that this technology could indeed be applied with the aim of developing this new method for colorectal cancer diagnosis and prevention. For that purpose, stool samples were taken from patients with this tumour, from patients with adenomatous polyps (pre-tumour stage) and from healthy subjects.
Compared to faecal immunochemical tests (FIT) to look for blood hidden in the stool, the procedure developed by the UA and Alicante Hospital, besides extracting, identifying and quantifying chemical compounds from faeces, "can be more sensitive, i.e. more effectively diagnose ill patients," according to the doctor and biomedical specialist Miren Alustiza, who carried out this work during her PhD thesis.
Once the test results were obtained, "we found that three chemical compounds, called p-cresol, 1H-indol and 3(4H)-dibenzofuranone, were present in both cohorts (healthy subjects and ill subjects), but at different levels," Antonio Canals explains.
Miren Alustiza and Lorena Vidal, UA senior lecturer and member of the research group, emphasise that colorectal cancer patients showed higher p-cresol and 3(4H)-dibenzofuranone concentrations and lower 1H-indol concentrations compared to healthy subjects.
"We do not know for sure why concentrations of both volatile compounds were found to be higher in colorectal cancer patients than in healthy subjects, but two possibilities are considered," Rodrigo Jover, head of Alicante General Hospital's Digestive Medicine Service, explains. Mr Jover has taken part in this research along with Mr Canals, Ms Vidal and Ms Alustiza.
"One possibility is that the tumour itself secretes substances that increase concentrations of these compounds, and the other is that this increase in certain volatile compounds is related to microbiota differences between cancer patients and healthy subjects," he says. "The latter is more likely, but we do not know."
According to Miren Alustiza, " p-cresol is a compound generated by the microbial degradation of aromatic amino acids, like tyrosine or phenylalanine. A possible hypothesis is that this could be due to changes in the bacterial flora, that these patients have an increase in p-cresol-producing bacteria," she highlights.
"Excess p-cresol can be caused by low absorption of aromatic amino-acids, a very protein-rich diet, or a genetic predisposition to a kind of cancer, inflammation or alterations in the microbiota," Lorena Vidal points out.
As for 3(4H)-dibenzofuranone, Vidal notes that another innovative aspect of the system developed by the UA and Alicante Hospital is that this compound (generated by p-cresol oxidation and with carcinogenic effects) had so far not been identified as a potential biomarker related to colorectal cancer or in patients with this tumour.
This new, easy-to-use method must now be perfected (validation of results with other patient cohorts) and can even complement already existing strategies for colorectal cancer prevention and diagnosis.