To undertake this study, the Oncologists and Pathologists worked with the University's Genome Institute to sequence more than 10 trillion chemical bases of DNA - repeating the sequencing of each patient's tumor and healthy DNA about 30 times to ensure accurate data. Huge computing facilities were required to analyze this amount of data. All patients in the trial had estrogen receptor positive breast cancer.
The researchers found that two mutations were relatively common in many of the patient's cancers. Once is present in about 40% of estrogen positive breast cancer and the other present in about 20%. They found a third mutation that controls programmed cell death and is disabled in about 10% of estrogen-receptor-positive cancers. This mutated gene allows cells that should die to continue living. Only two other genes had mutations that recurred at the 10% level.
They found 21 genes that also significantly mutated, but at much lower rates. Even though these mutations were relatively rare, they still involve thousands of women and are very important to understand.
These highly detailed genome maps are an important first step to designing therapy that is personalized to the patient. We do not know why treatment works for some women and not others. It may also help us understand aggressive types of breast cancer that are difficult to treat and occur in young women and African-American women.
Individual and personalized medicine is only possible when the cancer's genetics are known in advance. We are getting closer each day.