Comparison with published results. Tracey et al17 examined genes included on the CNIO Oncochip microarray platform, a subset of the genes included on the Affymetrix HG-U133 microarray platform. They identified 2 main subgroups of patients using hierarchical clustering. We compared this to our 3-cluster division determined through consensus clustering. Sample clustering in the space of genes identified by Tracey et al showed significant consistency with our results, despite only 21% overlap between genes used in clustering. We also examined a less optimized 2-cluster structure of our data for comparison, and found relatively good overlap with the 2-cluster structure of Tracey et al. (A) 3-cluster structure. 79% of samples overall were correctly classified. This result was significant (P < .001). (B) 2-cluster structure. 87% of samples overall were correctly classified using a 2-cluster structure. The result was again significant (P < .001). (C) Gene correlation. Genes were similarly classified for 71% of 130 common genes. Genes associated with more aggressive disease by Tracey et al were found to be associated with more advanced disease in our study as well. This finding was significant (P < .001).
