Next-generation sequencing is revolutionizing the way in which genomic-scale biological research is performed, and its effects are beginning to be translated medically. Large-scale international collaborations for the comprehensive sequencing of the genome, epigenome, and transcriptomes of cancers and corresponding 'normal' (germ-line) DNA are heralding the start of personalized medical genomics. The promise of eliminating conjecture when determining treatment approaches is certainly appealing for both patients and clinicians; however, several major issues must be resolved before next-generation sequencing will be adopted as a routine clinical tool for patients. This feature review explores the clinical potential and challenges of studying cancer genomes for personalized medical genomics.