A Clue from Under the Eaves

Among the most mysterious of all cancers is the one that afflicts the stomach. Why is it especially common in countries as far apart and as different as Japan, Finland and Chile? Why is it so rare in most of the U.S., and particularly in the Southern states--except among Negroes? Why, in all countries, is the disease associated with poverty?

Researchers have tried to explain the irregular incidence of stomach cancer on the basis of race, soils and a host of variables in eating and drinking habits. So far, even the most hopeful clues have led to dead ends. Last week, however, a U.S. researcher suggested an exotic explanation for the high incidence of stomach cancer among Koreans and other Far Eastern peoples. The culprit, Dr. David J. Seel told the James Ewing Society in Manhattan, may be a mold used in the preparation of a favorite Oriental delicacy, soya paste.

Dr. Seel, who has studied 919 cases of stomach cancer at the Presbyterian Medical Center in Chonju, South Korea, described the annual ritual of making soy sauce and soya paste. Each winter, virtually every household makes loaves of soybean mash and stores them in a cool, dark place, often under the eaves, so that they will get moldy. To make sure that the mold develops, some Koreans buy a pure culture and spread it on their loaves. By early spring, a furry black or gray growth covers the mash. The Koreans scrape off this "exuberant fungus," as Seel described it, and soak the loaves in brine for a month. Then they pour off the black liquid, which is soy sauce, and make the debris left in the crock into a stiff soya paste. Some Koreans eat little of the paste, but others indulge at the rate of five ounces or more a day.

The trouble, Seel suggests, may be twofold. The most widely used mold is Aspergillus flavus, some growths of which secrete substances called aflatoxins. For some animals, these are among the most powerful cancer-causing agents known. Moreover, says Seel, the stomach lining seems especially liable to damage, including cancer, in those with vitamin A deficiency. Among Koreans who had both low vitamin A readings and a high consumption of soya paste, stomach cancer was twice as common as among other groups.

Though soya-paste molds might go far to explain the high incidence of stomach cancer in most of the Orient, they offer no clues to medical researchers in Finland, Chile or Costa Rica. But a combination of vitamin A deficiency with comparable molds or diet contaminants could conceivably be found in those places. In the U.S., vitamin A deficiency is known to be prevalent among Southern Negroes, and aflatoxins have been found in peanuts.

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