No abstract

Genetic intratumoral heterogeneity is a natural consequence of imperfect DNA replication. Any two randomly selected cells, whether normal or cancerous, are therefore genetically different. We re-analyzed the extent of genetic heterogeneity within untreated cancers with particular regard to its clinical relevance. We found that homogeneity of predicted functional mutations in driver genes was the rule rather than the exception. In primary tumors with multiple samples, 97% of driver gene mutations in 38 patients were homogeneous. Moreover, among metastases from the same *