Smoking boosts the risk of developing a difficult-to-treat inflammation of the pancreas, and this risk may persist even after a person kicks the habit, new research from Denmark shows.

Excessive alcohol use and gallstone disease are thought to account for most cases of pancreatitis, Dr. Janne Schurmann Tolstrup of the University of Southern Denmark in Copenhagen and her colleagues note in the March 23 issue of the Archives of Internal Medicine, but smoking is not typically considered to be a risk factor for this illness.

To investigate whether smoking might indeed be harmful to the pancreas, Tolstrup and her team analyzed data from a 20-year study of 17,905 men and women. During follow-up, 235 people developed pancreatitis.

People who reported being smokers or ex-smokers at the study's outset were at greater risk of developing pancreatitis than people who had never smoked, the researchers found. Men and women who smoked 15 to 24 grams of tobacco daily (about 15 to 24 cigarettes) were 2.6 times as likely to develop pancreatitis as non-smokers.

The ex-smokers had about the same risk of pancreatitis as current smokers who used 1 to 14 grams of tobacco daily, or the equivalent of one to 14 cigarettes, the researchers found. This didn't appear to be because they had quit smoking due to illness, Tolstrup and her colleagues say, because eliminating the first two to four years of follow-up (when people who quit smoking because they were sick would have been expected to become ill) didn't affect the relationship.

The researchers also found that the effect of smoking was independent of alcohol use or gallstone disease. In fact, Tolstrup and her team estimate that 46 percent of the cases of pancreatitis they saw among study participants were due to smoking.

The percentage of smokers in the study was high, the researchers note; 58 percent of women and 68 percent men reported being smokers, while 15 percent of women and 19 percent of men were ex-smokers and 28 percent of women and 13 percent of men had never smoked.

But now, the researchers note, the prevalence of smoking has dropped sharply, with about 30 percent of people in most Western countries currently smoking.