Smoking Hastens Some Pancreatic Cancer
TUESDAY, July 10 (HealthScoutNews) -- Smoking doesn't just raise the risk of pancreatic cancer, it radically accelerates the onset of the highly virulent tumors in patients who have a rare inherited disorder of the digestive organ, new research says.
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 nonsmokers.
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 neutralize 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.
The risk of pancreatic cancer in the general population is a little under 1 percent. Smoking doubles the risk, and accounts for as many as 30 percent of the 28,000 cases that occur in the United States each year.
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 497 patients with a rare form of chronic pancreas inflammation called hereditary pancreatitis. This condition affects an estimated 1,000 people in the United States, about half of them related, and is believed to have made the journey from England back before the Revolutionary War.
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 tumors did so about 20 years earlier, on average, than nonsmokers -- 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.
What To Do
Dr. Albert Lowenfels, a surgeon at New York Medical College in Valhalla and a co-author of the study, says a number of genes, including the breast cancer gene BRCA-2, have been linked to pancreatic cancer.
"We know that about 10 percent of the people with pancreatic cancer in this country have a genetic factor" at work, Lowenfels says. "I think our results probably apply to many of these people. The public health message is, if you've got a relative with pancreatic cancer, you might be carrying one of the predisposing genes. If that's the case, the results of our study suggest that you really should avoid smoking." And drinking heavily, too, he adds.
To learn more about hereditary pancreatitis, check out Pancreas.org or Dr. Whitcomb's Web site.
For more on pancreatic cancer, try the Pancreatic Cancer Action Network or the MD Anderson Cancer Center.