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Colorectal cancer screening: an interview with Dr Donato F. Altomare 2

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.