Pancreatic cancer is notoriously deadly, killing some 95 percent of patients within five years of diagnosis. Actor Patrick Swayze died less than two years after he was diagnosed with the invasive disease. A pair of new studies examines the genetic history of pancreatic cancer, and one reports evidence that its evolution in the body might be a lengthy process, renewing hope for earlier diagnosis and more effective treatments.

As some scientists have used genetic sequencing to peer back into human evolutionary and migratory history, others are using the technology to trace the development and movement of cancer cells in the body. A team of researchers, led by Shinichi Yachida, The Sol Goldman Pancreatic Cancer Research Center at Johns Hopkins Medicine, was able to capture cancer cells from the tissues of various parts of the body in seven pancreatic patients shortly after their death and sequence the cells' DNA.

Assessing the genetic mutations and their accumulation over time in various tissues in the body, the researchers estimated that it took an average of about seven years from the initiating tumorigenic mutation to form a sizable tumor—and at least 10 years for the disease to start spreading to other parts of the body, at which point the disease is more easily detected but very difficult to treat. 

"For the first time, we have a quantifiable estimate of the development of pancreatic cancer and when it would be best to intervene," Christine Iacobuzio-Donahue, also of the Pancreatic Cancer Research Center and co-author of the study said in a prepared statement. "So there is potentially a very broad window for screening."

This slow development fits in well with population-based studies that have analyzed rates of mutation and spread of the disease. One such study estimated that the cancer might take several decades to move from an original tumor-causing mutation to a later stage more likely for clinical diagnosis.

The second group of researchers also used genetic sequencing to trace particular shifts in the pancreatic cancer genome. Their team, led by Peter Campbell of the Wellcome Trust Sanger Institute in the U.K., found that the disease is rather genetically unstable, racking up many chromosomal rearrangements as it progresses—both in the primary tumor and in other sites around the body.

Both studies were published in the October 28 issue of Nature (Scientific American is part of Nature Publishing Group).

Image of pancreatic adenocardinoma stain courtesy of Wikimedia Commons/KGH