The tumor microenvironment contributes important information in gene expression signatures but may be susceptible to sampling variance. Mesenchymal signatures in particular may be influenced by sampling of nonrepresentative regions with high stromal content. Appropriate pathology quality control is required to ensure reproducibility of gene expression signatures. Clin Cancer Res; 22(16); 3989-91. ©2016 AACRSee related article by Dunne et al., p. 4095.
©2016 American Association for Cancer Research.