Pancreatic Cancer Tumors May Take Decades to Kill

(CBS) Pancreatic cancer is a disease with few survivors - less than five percent after five years.

So it's long been thought of as a quick killer, but new research suggests just the opposite and gives hope to the idea that earlier diagnosis could alter outcomes for patients.

Scientists at the Johns Hopkins University School of Medicine and Howard Hughes Medical Institute studied cancer-causing genetic mutations taken from the bodies of people who had died from the disease.

Using a "molecular clock" technique to determine the age of the mutations, they found surprising results.

Many tumors took as long as 20 years to become lethal. On average, the pancreatic tumors they studied took 11.7 years to mature, 6.8 years to send cancer cells to another organ and another 2.7 years before the patient died.

"These tumors evolve over long periods - decades," said Bert Vogelstein in a statement. Vogelstein is a researcher at the Howard Hughes Medical Institute and one of the study's lead authors.

The tricky part is that pancreatic cancers typically don't show symptoms until it's far too late. The first sign is often jaundice and that only happens once the cancer has invaded the liver. Previously, scientists assumed the tumors grew fast and killed quick, leaving them few treatment options.

But the new findings suggest an early warning test could be developed to pick up on the cancer-causing mutations.

"For disease control in the future, this finding is paramount," Vogelstein said. "It gives us hope that we will eventually be able to reduce morbidity and mortality from pancreatic cancer through earlier detection."

The study was published in the journal Nature.

SCIENCE EXTRA: Wondering what a molecular clock is and how it can determine the age of a genetic mutation? It turns out human cancers mutate at a fairly steady rate. Scientists were able to count the number of mutations in the cadavers and, based on that, determine how old the first mutation was. The technique is also used by evolutionary biologists to track the ages of species.