A team of researchers led by scientists at the University of California, San Francisco (UCSF) has developed a way to uncover the evolution of human cancer cells, determining the order in which mutations emerge in them as they shift from a normal, healthy state into invasive, malignant masses.

The team developed a way of teasing gene mutations apart: long pieces of DNA in cancers often abnormally double in number; the technique relies on determining the sequence of the cancer DNA to see which mutations are also doubled, indicting they occurred before the duplication.

The researchers worked with a type of skin cancer known as cutaneous squamous cell carcinoma, which has among the highest numbers of mutations of any cancer, and also with a common type of ovarian cancer. By examining the accumulation of copies of TP53, a gene known to be involved with these forms of cancer, they found that complex changes in TP53 occurred earlier in most cases, rather than later, as had been previously believed.

The work may give doctors a new way to design diagnostics for detecting the signs of early cancers, when they are generally more treatable than in their later stages.

Ref.: Raymond J. Cho, et al., Temporal Dissection of Tumorigenesis in Primary cancers, Cancer Discovery, July 2011 [DOI: 10.1158/2159-8290.CD-11-0028]