Interview conducted by April Cashin-Garbutt, BA Hons (Cantab)
Please can you give a brief introduction to colorectal cancer?
Colorectal cancer is a malignant neoplasm affecting the large bowel and the rectum mainly after the 5th decade of life and representing the second cause of death for cancer in western countries (the third in women). In about 15-20% of patients there is an inherited predisposition.
Despite major improvement in diagnosis and treatment achieved in the last decades, still a large proportion of these patients are treated in an advanced stage of the disease when the curative managements are impossible.
Nevertheless this type of cancer could be prevented or at least diagnosed in its early stage because most of the cancers originate from the slow malignant transformation of colonic polyps which could be easily removed by endoscopy. Recent studies have confirmed that patients in whom this cancer was discovered because of a screening test have better prognosis compared to patients with symptomatic disease
What screening procedure is currently used for colorectal cancer?
Since this cancer and its benign precursor (polyp)can release a minimal quantity of blood, an immunochemical test looking to occult traces of blood in the feces is the method of screening usually employed as a mass screening tool (the FOBT).
However this test has several drawback including a scarce patients compliance and a low accuracy leading to an unacceptable high proportion of useless colonoscopy (which are expensive, risky and bad tolerated by the patients) and of missing cancers or polyps.
Please can you tell us about the simple breath analysis that could be used for colorectal cancer screening?
Actually the test is very simple, although the type of breath analysis is not so easily available in every laboratory. The test consists in collecting the exhaled breath air in a Tedlar bag (an inert plastic material).
Then the air is absorbed on a special cartridge which is inserted into a Gas chromatography and the results read by a mass spectrometer. These complex machines are able to identify and define the small volatile molecules (VOCs).
How does colorectal cancer patients’ breath differ from the breath of healthy people?
The VOCs are the small molecules produced by the final metabolism of the cells and reflect their “normal” status. Cells affected by genetic mutations like cancer cells have some different metabolic processes inside which produce VOCs different from normal cells.
These components are released into the blood stream irrespectively of their site of origin and when they reach the lung, they can be released in the exhaled breath.
How does the breath analyser capture this difference?
The pattern of 15 of the several VOCs detected in the breath were found to have a different behavior in patients compared with normal controls. This means that these 15 VOCs are present in different concentrations in the two groups. A sophisticated statistical analysis (probabilistic neural network analysis) is the best method to analyze this difference.
What impact do you think this breath analyser will have on colorectal cancer screening?
A breath analysis has a better compliance from the population and in our study it showed a higher accuracy (85% in the trial phase and 75% in the prospective blind phase) compared to the FOBT.
If the data will be confirmed in a large trial comparing the breath test with the FOBT, it will revolutionize the way to do screening, because it probably could be applied to other types of cancer.
Are there any plans to use breath analysis to screen for other diseases?
The search and understanding of these small molecules is a new field of science called metabolomics and this approach is nowadays one of the most exciting new fields of research for screening several types of cancer and probably other diseases (chronic inflammatory diseases).
Where can readers find more information?
You can find the article published in the British Journal of Surgery:
About Dr Donato F. Altomare
Associate Professor of Surgery, president of the II School of Specialization in General Surgery and Inter-Department Research Center for Pelvic Floor Diseases at University of Bari, Bari, Italy
Past President of the Italian Society of ColoRectal Surgery
Past Associate Director of the International Society of University ColoRectal Surgeons
Chairman of the program Committee and member of the Research Committee of the European Society of Coloproctology
Co-Editor of Colorectal Diseases, Technique in Coloproctology, and Nutrition and Metabolism, Associate Editor of Diseases of the Colon and Rectum