Smoking doesn't just raise the risk of pancreatic cancer, it radically accelerates the onset of the highly virulent tumours in patients who have a rare inherited disorder of the digestive organ, new research says.
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Smokers with hereditary pancreatitis, which causes chronic inflammation of the pancreas, double their already heightened risk of cancer there, and tend to develop the disease 20 years earlier than non-smokers.
Although the study looks only at patients who have this exceedingly rare condition, the researchers say it sends a message to everyone with a genetic predisposition to an aggravated pancreas: don't smoke.
A report on the work appears as a research letter in the July 11 issue of the Journal of the American Medical Association.
The pancreas consists of a triumvirate of cells, the most common being the acinar tissue that make digestive juices to break down food. Following those are the hormone-secreting islet cells, best known for generating the insulin that helps the body harness energy in blood sugar. Finally come the duct cells, which form a network of canals to channel digestive juices into the intestines. They're also a built-in heartburn-relief factory, secreting bicarbonate to neutralise stomach acid.
Pancreatic cancer strikes duct cells, which although making up about only 5 percent of the organ divide rapidly and are thus more vulnerable to mutations.
In the latest work, Dr David Whitcomb, a gut expert at the University of Pittsburgh, and his colleagues in the United States and Europe studied patients with a rare form of chronic pancreas inflammation called hereditary pancreatitis.
People with hereditary pancreatitis, which typically shows up by age 10, are 40 to 50 times above the normal risk of developing pancreatic cancer, and Whitcomb's group wanted to learn how smoking affected those odds.
Nineteen of the 497 patients had biopsy-confirmed pancreatic cancer, and of those 11 were current or former smokers. Six others had never smoked, while the tobacco history of the remaining two couldn't be established.
In other words, the researchers say, smoking doubled the risk of pancreatic cancer in this special group of patients, just as it does for the typical person. However, Whitcomb's team found, smokers who developed tumours did so about 20 years earlier, on average, than non-smokers - age 50 vs. age 70.
"I think that's probably one of the most dramatic interactions that there is," Whitcomb says. "It's hard to get much worse than that."
Why smoking accelerates the onset of pancreatic cancer is a mystery, Whitcomb says. "There are many toxins and carcinogens in tobacco smoke. But I don't know which one is doing it."
Heavy drinking also exacerbates the risk of pancreatic cancer for everyone, according to the researchers, but particularly for people with the inherited inflammatory disorder.
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