Liver cancer study on tap
Adding clay to West Siders’ diets is eyed.
By Don Finley
San Antonio’s notoriously high rates of liver cancer might be due, in part, to the food we eat, experts say. Now they want to find out if adding a little clay to the diet, among other changes, might lower that risk.
The idea came from a recently published study conducted in three West Side ZIP codes — 78207, 78228 and 78237 — where liver cancer rates are high.
That study found nearly 12 percent of residents tested had aflatoxin, a toxic mold that grows on corn, peanuts and other grains, in their urine.
That percentage — and the amounts of aflatoxin — isn’t as high as in some developing countries, where the toxin is common and liver cancer rates are very high. But health officials said it is worrisome, particularly in combination with other risk factors.
Now those same researchers at the Metropolitan Health District and Texas A&M University are preparing a new, three-year study of the same neighborhoods, hoping to learn whether changes in diet and a clay-based dietary supplement can reduce that risk.
“I see this as a food safety project,” said Kyle Cunningham, manager of Metro Health’s Center for Environmental Health. “Our food in the United States is extremely safe. But aflatoxin is a very potent carcinogen. And in a population where other factors are at play, I think aflatoxin exposure probably would bring up the rates of liver cancer.
Those other factors include hepatitis C, a leading cause of liver cancer in this country. Seven percent of the residents in the earlier study were infected with the virus. Other causes of liver cancer include diabetes, alcohol use and chemical exposures.
Some residents have pointed to the latter, arguing that pollutants from the shuttered Kelley AFB seeped into a shallow aquifer over the decades and exposed residents. Experts have tried to assure residents there’s no link, but many are unconvinced.
“Our ultimate goal is to try and bring down the high rates of liver cancer that we see on the West Side of San Antonio,” Cunningham said. “Aflatoxin is a very potent carcinogen, especially when there are other factors involved — such as hepatitis. And we found quite a bit of hepatitis C..”
Of the 184 residents that took part in the earlier study, those with aflatoxin in the blood also reported eating higher amounts of corn, rice and peanut products.
Clay additives are already used in some animal feeds to reduce aflatoxin exposure. Timothy Phillips, chairman of toxicology and an expert in aflatoxin at A&M, has developed a similar additive for human use. The specially formulated clay supplement binds to aflatoxin in the digestive system.
The researchers hope to recruit 500 residents for the new study. The City Council is expected to consider Metro Health’s accepting $334,540 as a share of grant funds for the project today.
High rates of liver cancer aren’t limited to the West Side. All of Bexar County suffers from one of the highest rates of liver cancer — and liver cancer deaths — in the state.
Between 2004 and 2008, Bexar led all other large counties with 13.7 cases per 100,000 population, well above No. 2 Harris at 9.3. It also led in liver cancer deaths at 10.9 per 100,000, again followed by Harris at 7.4.