Systematic pan-cancer analysis of tumour purity
A partir de données issues du projet "The Cancer Genome Atlas" portant sur plus de 10 000 échantillons tumoraux (21 types de cancer), cette étude analyse le niveau de "pureté" des échantillons, c'est-à-dire la proportion de cellules cancéreuses et de cellules du micro-environnement tumoral qu'ils contiennent
The tumour microenvironment is the non-cancerous cells present in and around a tumour, including mainly immune cells, but also fibroblasts and cells that comprise supporting blood vessels. These non-cancerous components of the tumour may play an important role in cancer biology. They also have a strong influence on the genomic analysis of tumour samples, and may alter the biological interpretation of results. Here we present a systematic analysis using different measurement modalities of tumour purity in >10,000 samples across 21 cancer types from the Cancer Genome Atlas. Patients are stratified according to clinical features in an attempt to detect clinical differences driven by purity levels. We demonstrate the confounding effect of tumour purity on correlating and clustering tumours with transcriptomics data. Finally, using a differential expression method that accounts for tumour purity, we find an immunotherapy gene signature in several cancer types that is not detected by traditional differential expression analyses.