Fig. 4

Hierarchical clustering analysis and VIP score plots of PLS-DA of 22 metabolites in 30 samples from 5 patients with cT1 and T2 stage tumors. a Hierarchical clustering analysis of 22 metabolites in 30 samples from 5 patients with cT1- and cT2-stage tumors. Metabolite levels were used to color code individual samples from blue (low concentration) to purple (high concentration). Tree clusters and shorter Euclidean distances indicate greater similarities between samples or metabolites. The red color of the top bars represents group 1, and the other color represents groups 2, 3, 4, 5, and 6. b The VIP score plots of PLS-DA in positive ion mode. c The VIP score plots of PLS-DA in negative ion mode. The vertical coordinate represents the M/Z of each metabolite, and the horizontal coordinate is the weight value of each metabolite. It can be seen from the score plot that there are 5 metabolites in the positive ion mode and 6 in the negative ion mode. PLS-DA: partial least squares discriminant analysis. M/Z: mass-to-charge ratio. VIP: Variable Importance in the Projection