Cancer detection in exhaled breath

Did it ever occur to you that cancer can be detected by analysis of your breath? (Something that dogs are capable of!)

Reporting its work in the British Journal of Cancer, a research team headed by Hossam Haick demonstrated that a nanosensor array made of gold nanoparticles can differentiate between healthy patients and those with lung, breast, colorectal, and prostate cancers based on a single exhaled breath. The nanosensor array detects trace chemical known as volatile organic compounds (VOCs) that are generated by cancer cells and released into the blood stream. In addition, the investigators found that patients with each of the four cancers had characteristic VOC profiles, though these differences were not well-differentiated enough to diagnose a specific form of cancer.

To test their device, the researchers collected exhaled breaths from 177 volunteers, 96 of whom had just been diagnosed with lung, breast, colorectal, or prostate cancer and had not yet received therapy. Each test subject spent up to five minutes breathing purified air before exhaling into a collection bag; this was to ensure that any VOCs detected in the subjects’ breaths did not originate in the ambient air that they were breathing. The researchers used collection bags made of chemically inert Mylar so that the bags could be reused after thorough cleaning with ultrapure nitrogen gas.

After testing the samples using their nanosensor array, the investigators repeated their analysis using gas chromatography-mass spectrometry (GC-MS), a highly accurate analytical method that would be too slow and costly to use in any routine diagnostic procedure. GC-MS also requires the use of a pre-concentration step in order to detect the low levels of VOCs in human breath. Comparison of the results obtained using the two techniques showed that the nanosensor arrays was the more accurate of the two methods as far as discriminating between healthy patients and those with cancer. More importantly, results from the nanosensor array – unlike those obtained using GC-MS – were not dependent on the gender, age, ethnic origin, family cancer history, intake of food additives, drug treatment, exposure to environmental toxins, and smoking habits.

The reported results could lead to the development of an inexpensive, easy-to-use, portable, non-invasive tool that overcomes many of the deficiencies associated with the currently available diagnostic methods for cancer.

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