Diet and high risk of stomach cancer in Shandong, China.

A case-control investigation involving interviews with 564 stomach cancer patients and 1131 population-based controls was conducted to evaluate reasons for the exceptionally high rates of stomach cancer in Linqu, a rural county in Shandong Province in northeast China. Daily consumption of sour pancakes, a fermented indigenous staple, was associated with a 30% increase in risk. Risks of stomach cancer were also increased by 2- to 3-fold among persons with prior chronic gastritis or gastric ulcer, by 80% among those with stomach cancer in a family member, by 50% among men who smoked one or more packs of cigarettes/day, by 40% among those who preferred salty foods, and by 50% among families with moldy grain supplies. In contrast, risks tended to decrease in proportion to increasing consumption of fresh vegetables and fruits. This protective effect was more pronounced for vegetables, with those in the highest quartile of intake at less than one-half the risk of those in the lowest. Stomach cancer risks also declined with increasing dietary intake of carotene, vitamin C, and calcium, but not retinol. These findings provide leads to dietary factors that contribute to the high rates in Linqu, where stomach cancer is the leading cause of cancer and has not yet begun to decline as in other parts of the world.