Not long ago, doctors hoping to cure human disease spent a lot of time in the laboratory looking through microscopes. But big data has changed all that. Now, many physician scientists spend a lot more time in front of the computer analyzing large datasets which have fundamentally changed how they find cancer treatments. We asked Dr. Rakesh Nagarajan, director of the Institute of Clinical and Translational Sciences Biomedical Informatics Program at Washington University, about how drastic this change is, what the barriers are, and when we might realize the full potential of precision medicine for cancer prevention and treatments.