Over the past decade, comprehensive sequencing efforts have revealed
the genomic landscapes of common forms of human cancer. For most
cancer types, this landscape consists of a small number of "mountains"
(genes altered in a high percentage of tumors) and a much larger
number of "hills" (genes altered infrequently). To date, these studies
have revealed ~140 genes that, when altered by intragenic mutations,
can promote or "drive" tumorigenesis. A typical tumor contains two
to eight of these "driver gene" mutations; the remaining mutations
are passengers that confer no selective growth advantage. Driver
genes can be classified into 12 signaling pathways that regulate
three core cellular processes: cell fate, cell survival, and genome
maintenance. A better understanding of these pathways is one of the
most pressing needs in basic cancer research. Even now, however,
our knowledge of cancer genomes is sufficient to guide the development
of more effective approaches for reducing cancer morbidity and mortality.