DNA analysis of thousands of tumors from UK’s National Health Service (NHS) patients has found a “treasure trove” of clues about the causes of cancer, with genetic mutations providing a personal history of the damage and repair processes each patient has been through. In the largest study of its kind, a team of scientists led by Professor Serena Nik-Zainal, PhD, from Cambridge University Hospitals (CUH) and the University of Cambridge, analyzed the complete genetic make-up or whole-genome sequences of more than 12,000 NHS cancer patients. Because of the vast amount of data provided by whole genome sequencing, the researchers were able to detect patterns in the DNA of cancer--or “mutational signatures” – that provide clues about whether a patient has had a past exposure to environmental causes of cancer such as smoking or UV light, or has internal, cellular malfunctions.