In the single largest cancer genomics investigation reported to date, Washington University scientists have sequenced the whole genomes of tumor cells and healthy cells from 46 breast cancer patients. Their work reveals the incredible complexity of cancer genomics and provides an important glimpse into new routes for personalized medicine. The researchers studied DNA samples from patients with estrogenreceptor-positive breast cancer, the most common form of breast cancer, accounting for three-quarters of cases. Repeating the sequencing about 30 times to ensure accurate data, they analyzed 10 trillion base pairs of DNA, comparing tumor cell DNA to DNA of the same patient’s healthy cells.
“Cancer genomes are extraordinarily complicated,” says Matthew Ellis, MB, BChir, PhD, an oncologist at the Alvin J. Siteman Cancer Center and a lead investigator on the project. “This explains our difficulty in predicting outcomes and finding new treatments.”
Confirming previous work, Ellis and colleagues at Washington University’s Genome Institute found two tumor mutations that were relatively common. They also found an additional 22 genes that were also significantly mutated but at low rates. Despite the rarity of these mutations, Ellis stresses their importance.
“Breast cancer is so common that mutations that recur at a 5 percent frequency level still involve many thousands of women,” he says. Ideally, Ellis says, the goal is to design treatments by sequencing the tumor genome when the cancer is first diagnosed.
Learn more about genome research at Washington University and Barnes-Jewish Hospital.