Temporal Dissection of Tumorigenesis in Primary Cancers

The earliest genetic abnormalities in cancer represent a unique opportunity for timely clinical diagnosis. Classic deep sequencing of tumors identifies many aberrations acquired later in cancer progression. In this study, data regarding simple mutation and chromosomal aberration were integrated to trace the evolution of cutaneous squamous cell carcinomas and ovarian adenocarcinomas. Only after the second allele of TP53 was lost did the genome enter a window of extreme genomic vulnerability, in both cancer types, eventually acquiring more than 100,000 mutations in skin cancers. Inactivating Notch mutations were also identified as prevalent secondary changes. These results add context to the idea of TP53 mutation as dominant negative and occurring later in tumorigenesis.]]> Between the years of 2006 and 2010, one woman and seven men were enrolled in the study of skin cancer. Their ages ranged from 61 to 87 years. Informed consent was provided according to UCSF Committee on Human Research guidelines for large-scale genetic analysis. Data sharing is allowed so long as identity is not revealed. Board certified dermatopathologists confirmed the diagnosis of squamous cell carcinoma of the skin, from biopsies, for all study samples. Tissue was isolated using curettage before Mohs micrographic surgery. Control samples were obtained from adjacent normal skin.]]>