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Albert Einstein famously said, “If I had an hour to solve a problem, I’d spend 55 minutes thinking about the problem and 5 minutes thinking about the solutions.”
While more robust cancer treatments are indubitably necessary, cancer detection is a crucial part of providing effective patient care. Early detection is important because if cancerous tissue is identified before it has spread to other parts of the body, it is often easier to treat. For example, current head and neck cancer therapies are effective in treating early-stage cases. However, morbidity is high for late-stage patients. Recognizing the potential benefits of detecting the disease early, a team at Flinders University recently published work on developing a system to detect head and neck cancer by simply sampling a patient’s breath.
The key to their detection system is volatile organic compounds (VOCs). These are organic molecules that usually exist in the gaseous phase at biological temperatures. Although we cannot see them, human breath contains many distinct VOCs. Collecting a breath sample and analyzing the profile of VOCs provides insight into the biochemical processes happening inside a patient’s cells. This means that VOCs can highlight abnormality in the levels of cell death, oxidative stress, or inflammation. Ongoing research has populated a database of specific VOCs that may signal the presence of cancer so physicians can read these warning flares that the body is sending out in the breath of patients.
In their study, the Flinders team collected breath samples from two groups of participants. The control group consisted of 50 healthy adults who were once suspected of having head and neck squamous cell carcinoma (HNSCC), but were ultimately determined not to. The second group consisted of 50 people who did have HNSCC.
The VOCs in each breath sample were analyzed with a common analytical technique called mass spectrometry. A mass spectrometer takes in a sample and gives molecules within it a positive charge. The charged molecules are then accelerated through a tube, where they are deflected by a magnetic force. The strength of the magnetic force felt by each molecule dictates the rate at which it will curve its path and reach the detector. Data from the detector informs the mass of compounds in the sample and in what relative amount each compound was present.
A statistical model based on the mass spectrometer data was able to accurately classify a participant in the study as control or having cancer with an accuracy of 83%. This is not the first study to have demonstrated results in this range of accuracy, but according to the authors it is the largest sample size study to have done so.
The current hope is not that this cancer breath test replaces more rigorous diagnostic tests, but rather that it serves as a fast intermediate test. The breath test collection takes one minute. Physicians can rapidly know whether to refer a patient for further testing immediately or whether the patient can afford to wait and monitor symptoms. Importantly, this could help alleviate some pressure on health center resources, as diagnostic tests for head and neck cancer require referral to specialists and thus more advanced equipment.
According to the authors, the next step should be a more rigorous trial with at least 5,000 participants. By Einstein’s rule of thumb, it may be justified to spend 55 minutes thinking about the problem, but if researchers at Flinders are successful, physicians may need only a minute.
Edited by MaryAnn Bowyer
Dharmawardana N, Goddard T, Woods C, Watson DI, Ooi EH, Yazbeck R. Development of a non-invasive exhaled breath test for the diagnosis of head and neck cancer. British Journal of Cancer. 2020. doi:10.1038/s41416-020-01051-9
Janfaza S, Khorsand B, Nikkhah M, Zahiri J. Digging deeper into volatile organic compounds associated with cancer. Biology Methods and Protocols. 2019;4(1). doi:10.1093/biomethods/bpz014