Early stage diagnosis of oral cancer using 1H NMR-based metabolomics

Abstract

Oral cancer is the eighth most common cancer worldwide and represents a significant disease burden. If detected at an early stage, survival from oral cancer is better than 90% at 5 years, whereas late stage disease survival is only 30%. Therefore, there is an obvious clinical utility for novel metabolic markers that help to diagnose oral cancer at an early stage and to monitor treatment response. In the current study, blood samples of oral cancer patients were analyzed using nuclear magnetic resonance spectroscopy to derive a metabolic signature for oral cancer. Using multivariate chemometric analysis, we obtained an excellent discrimination between serum samples from cancer patients and from a control group and could also discriminate between different stages of disease. The metabolic profile obtained for oral cancer is significant, even for early stage disease and relatively small tumors. This suggests a systemic metabolic response to cancer, which bears great potential for early diagnosis.

Figure 1

Superimposition of two representative ¹H NMR spectra (projections of JRES spectra), which show the average signals from the serum samples of healthy subjects (blue line) and patients with disease (red line) after application of a generalized log transformation. Predominant metabolite resonances are labeled on the spectrum. Ala indicates alanine; Gluc, glucose; Lac, lactate; Val, valine.

Figure 2

Principal components analysis scores plot of ¹H NMR spectra of human blood sera from OSCC patients (●) and from healthy controls (▼).

Figure 3

PLS-DA scores plot of ¹H NMR spectra of human blood sera using two classes: OSCC patients (● early and ■ late stage diseases) and healthy controls (▼).

Figure 4

Loadings plots for the first principal component for different regions of the spectrum. A representative NMR spectrum of human serum from an OSCC patient is shown above the loadings plots. Signals representing the most relevant discriminatory metabolites of healthy individuals (positive loadings) and OSCC patients (negative loadings) are labeled (A and B). 2HB indicates 2-hydroxybutyrate; 3HB, 3-hydroxybutyrate; Ac, acetone; Ace, acetate; AceAce, acetoacetate; ACL, acetyl-l-carnitine; Ala, alanine; Asn, asparagine; Bet, betaine; Car, carnitine; Cho, choline; Cit, citrate; Cr, creatine; Cre, creatinine; DMG, dimethylglycine; EtOH, ethanol; Gln, glutamine; Gluc, glucose; Gly, glycine; Lac, lactate; Lys, lysine; MeOH,methanol; Orn, ornithine; Pro, proline; Pyr, pyruvate; Sar, sarcosine; Ser, serine; Val, valine.

Figure 5

Schematic representation of the most relevant metabolic differences between oral cancer patients and healthy controls.

Figure 6

Loadings plots (latent variables) from a PLS-DA analysis of OSCC patients showing metabolites that discriminate between early (positive loadings) and late stage diseases (negative loadings). A representative NMR spectrum of human serum from an OSCC patient is shown above the loadings plots.