Personalised medicine is an emerging field in which physicians use diagnostic/prognostic tests to decide which medical treatments will work best for an individual patient. By combining diagnostic/prognostic data with clinical assessment, health care providers are able to develop targeted treatment and prevention plans, moving towards realising precision medicine.

There is now increasing evidence linking oral health to systemic diseases. As such, human saliva is gaining momentum as a diagnostic fluid for the future. Saliva is ideal as a diagnostic medium due to its non-invasiveness, ease of sampling and the option of collecting multiple samples by non-healthcare persons. Saliva is produced by salivary glands, which are interconnected with blood vessels. We are using saliva as a diagnostic fluid to detect ischemic heart disease and heart failure. The mean C-Reactive Protein (CRP) levels in the saliva collected from controls was 285 pg/mL and in cardiac patients was 1680 pg/mL (p<0.01). Analysis of CRP concentrations in paired serum and saliva samples from cardiac patients gave a positive correlation (r2 = 0.84, p < 0.001). Similarly, salivary NT-proBNP levels in the healthy controls and HF participants were <16 pg/mL and 76.8 pg/mL, respectively. The salivary NT-proBNP immunoassay showed a clinical sensitivity of 82.2% and specificity of 100%, positive predictive value of 100% and negative predictive value of 83.3%, with an overall diagnostic accuracy of 90.6%.

Epigenetic changes are a hallmark of oncogenesis, represented by DNA methylation and miRNA profiles. Salivary DNA methylation levels of RASSF1, p16INK4a, TIMP3, PCQAP 5’ and PCQAP 3’ combined into a panel, using logistic regression analysis, gave a sensitivity of 71% and a specificity of 80% discriminating healthy control smokers and non-smokers (n=122) from head and neck cancer (HNC) patients (n=133). Furthermore, using a multi-marker logistic regression analysis, a panel of nine salivary miRNA demonstrated a sensitivity of 95% and a specificity of 93% (AUC = 0.98) when discriminating HNC patients (n=100) from precancer patients (n=29).

Conversely, blood as a medium for ‘Liquid Biopsy’ has also come to the fore in HNC management. Metastases remains the major cause of death in HNC patients; circulating tumour cells (CTCs) derived  from  primary and secondary sites provide a comprehensive representation of the tumour burden in cancer patients’ at any one time. We have demonstrated that CTCs can be isolated from HNC patients before clinically evident metastasis, using a novel, microfluidic technology and now we have exciting preliminary data correlating CTC presence to clinical outcomes during the course of treatment. This microfluidic technology has the ability to transform scientific findings into translational outcomes and tangible health benefits by identifying HNC patients at risk of developing metastasis earlier than conventional techniques can.  Identifying HNC patients before clinical metastasis (via a blood draw to assess CTCs) will allow us to develop treatment strategies either by intensifying or de-escalating treatments, and could revolutionize the management of HNC patients with concomitant increase in survival rates and significant reduction of healthcare costs.