50 Breast Cancer Genomes Sequenced

In one of the largest cancer genomics investigation reported to date, scientists have sequenced the whole genomes of tumors from 50 breast cancer patients and compared them to the matched DNA of the same patients' healthy cells. This comparison allowed researchers to find mutations that only occurred in the cancer cells. The scientists uncovered incredible complexity in the cancer genomes, but also got a glimpse of new routes toward personalized medicine. The work was presented at the American Association for Cancer Research 102nd Annual Meeting 2011. In all, the tumors had more than 1,700 mutations, most of which were unique to the individual, says Dr. Matthew J. Ellis, professor of medicine at Washington University School of Medicine in St. Louis and a lead investigator on the project. "Cancer genomes are extraordinarily complicated," Dr. Ellis says. "This explains our difficulty in predicting outcomes and finding new treatments." To undertake the massive task, Washington University oncologists and pathologists at the Alvin J. Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine collaborated 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. "The computing facilities required to analyze this amount of data are similar in scale to those of the Large Hadron Collider, used to understand the workings of sub-atomic particles," Dr. Ellis says. The DNA samples came from patients enrolled in a clinical trial that Dr. Ellis is leading for the American College of Surgeons Oncology Group. All patients in the trial had what is called estrogen-receptor-positive breast cancer.