The Independent reports that smoking 15 cigarettes can cause a genetic mutation. Describing a new study that attempts to map the tumor-causing mutations, the article identifies the first documentation of "all of the mutations acquired during the lifetime of a cancer patient."

By studying the cancer patients' genomes, scientists hope to figure out the cause of cancer (in other words, what makes a healthy cell become a tumorous cell) and, thus, ways to successfully treat the disease. The article references research done on a lung-cancer victim who had DNA mutations linked to toxins from cigarette smoke and another patient with skin cancer who had mutations caused by sunlight.

The Wellcome Trust Sanger Institute in Cambridge, U.K., performed the research, called the Cancer Genome Project. They hope to decode the entire DNA sequence for a tumor cell to better identify the mutations. The Independent cites researcher Dr. Peter Campbell, who says his study has identified some specific mutations caused by cigarette toxins. "We can say that one mutation is fixed in the genome for every 15 cigarettes smoked," he says. His research sequenced the cancer cell genomes 60 times and compared it to the map of a healthy cell from the same patient.

The successful gene maps allow the scientists to investigate the history of the tumor cells, pointing to specific "imprints of ... environmental mutagens [mutation-causing agents] on DNA." In other words, for the first time, the researchers can look to the specific causes of these prevalent cancers and better inform their research of treatment and prevention.