Special Section: Cancer

An unstable genome is a hallmark feature of nearly all solid tumors and adult-onset leukemias; this instability first appears early in tumor progression, and can take several forms. While the source of instability has been established for many human family cancer syndromes to reside in inherited defects in genes relating to DNA repair, the genes generating genomic instability in sporadic cancers remain largely unknown. A clear pattern has emerged of cancer as a disease of genomic instability within a finite window, leading through accelerated somatic evolution to a genomically heterogeneous population of cells naturally selected for their abilities to proliferate and invade, while simultaneously evading host defenses.