Figure 4

Relative ion intensity profiles of marker peaks used in predictive algorithms of tumour/mucosa clinico-pathological features. The peak intensity profiles of the top two-ranked scoring peaks are shown for tumour spectra (A) for classifying differentiation and disease recurrence and for normal mucosa spectra (B) for classifying lymph node involvement (see Table 2). The performance of predictive models for these clinico-pathological features are shown in additional file 4 (differentiation), in additional file 5 (disease recurrence) and in additional file 6 (lymph node involvement). The t-test P value is given for each marker peak.