Oral cancer: Breath of death

Key Points

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Main

Sir, yet another patient presented late to our outpatient service with a large oral growth. Questioning confirmed early self-detection several months previously. Late diagnosis of malignancies in developing nations is due to limited access in rural areas to biopsy services. Anecdotal discussion with colleagues confirms a 'breath of death', a peculiarly pungent halitosis noted in the breath of oral malignancy patients. Our hypothesis is that the genetic makeup of tumours and their distorted molecular pathways lead to synthesis of unique proteins that generate 'signature odours'. If this were true, a paradigm shift in early detection of malignancies might rely not on visual detection but on analysis of patients' volatile molecular samples. The keen sense of smell of dogs is already used for detection of narcotics and explosives; pattern analysis to detect malignancies in this manner has been demonstrated.¹

Reverse engineering of biological olfactory mechanisms and pathways may improve electronic olfaction to enable reliable diagnostics.² It is not impossible to imagine a future where a compact, affordable electronic olfaction module plugs into a clinician's smartphone enabling odour analysis even at locations remote from healthcare facilities (Fig. 2). Algorithms comparing detected molecules with online databases of 'olfactory signatures' would suggest a mathematical probability of oral malignancy. Animals' reliance on olfaction to detect prey, predators and mates hints at the potential sensitivity and specificity of electronic olfaction.

Figure 1

Diagram of electronic olfactory diagnostic module

The non-invasive quality of odour analysis promises speed, painlessness and affordability. Apart from malignancies, odour analysis might help to detect even metabolic disorders in the doctor's office. Even while writing this letter, news has emerged that malaria could be diagnosed by a breath test. We anticipate this to be a future path of research in computational biology. Odours have never been more exciting for life sciences; clinicians of yore would be surprised and pleased at such emerging new diagnostic tools.³