Clustering of the training set and survival analysis. Unsupervised analysis based on the MGMT methylation patterns. (A) A hierarchical cluster analysis of the methylation of the MGMT promoter in 53 samples. Cluster 1 (Black), strongly methylated samples; cluster 2 (red), moderately methylated; cluster 3 (green), slightly methylated; cluster 4 (blue), mostly unmethylated. The columns below the clustering show the results obtained using MSP. The gray column indicates methylated, and the white column is unmethylated samples. (B, C) Survival analysis was performed between all combinations of the four cluster subgroups. For PFS, the analysis showed statistically significant differences between cluster 1 and cluster 4 (p = 0.00491) and between cluster 2 and cluster 4 (p = 0.0204). For OS, there was no statistically significant difference between any combination of the four clusters, but there was a trend toward a difference between cluster 1 and cluster 4 (p = 0.0533).