Background: The serum pepsinogen I to II ratio (PG I/II) is related to the risk of stomach cancer. Smoking is an established risk factor for stomach cancer. The effect of smoking on the change in PG I/II over a 7-year span was investigated.
Methods: Data were from 1889 male subjects who underwent phlebotomy in both 1989 and 1996. The subjects were classified into smoking and non-smoking groups: those who continued smoking, and those who never smoked during the span. The subjects were stratified by Helicobacter pylori status (negative or positive) and age (20-29 or 30-56 years in 1989), and the change in PG I/II was compared between the smoking and the non-smoking groups.
Results: PG I/II increased less (age adjusted mean +/- standard error of the difference was 0.209 +/- 0.069, p < 0.001) and less frequently in the smoking group (65.8% versus 58.9%, p = 0.002), but these differences were not clear among H. pylori-positive subjects.
Conclusions: The less frequent increase (i.e. a more frequent decline) in PG I/II may be a long-term effect of smoking, although the effect is not clear under H. pylori infection. The decline may be one of the mechanisms through which smoking elevates the risk of stomach cancer.