Unsupervised-hierarchical cluster analysis using 43 samples and 2,863 genes that contain four or more probes. Genomic copy-number gains or losses are indicated by red and green squares, respectively, for each gene. The length of the heat map is compressed as a 1:60 ratio for visualization. Samples were classified into three clusters: stable, intermediate, and unstable, which are marked with grey, yellow, and pink frames, respectively. The numerals under the dendrogram show five pairs of concurrent tumours. The background colours of the sample names represent morphological categories: light and dark grey indicate non-invasive low-grade and high-grade neoplasms, respectively; light and dark pink indicate invasive intramucosal tumours and intramucosal parts of submucosal or deeper tumours, respectively.