le with low levels of zinc in their tissues may be at increased risk for developing cancer of the esophagus, according to research reported in The Journal of the National Cancer Institute.
In the study, investigators determined zinc levels in esophageal biopsy samples obtained from 132 residents of Linzhou, China in 1985. Of these subjects, 60 subsequently developed esophageal cancer and 72 did not.
People in the highest quartile of zinc levels were 79 percent less likely to develop esophageal cancer than those in the lowest quartile, Dr. Christian C. Abnet, from the National Cancer Institute in Bethesda, Maryland, and colleagues report.
This finding supports studies conducted in animals showing that zinc deficiency enhances the effects of certain nitrosamines, which act as esophageal carcinogens in rodents.
While the current findings are interesting, their applicability to US or European populations is unclear, the authors warn. "We did this study in a population that is at extremely high risk for esophageal cancer," Abnet told. "Also, these subjects in China probably have fairly low zinc intake and tissue levels compared with a US population."
He said his group is interested in conducting a similar study in populations with a lower risk of esophageal cancer and higher zinc levels.
"We don't have any data regarding an association with esophageal cancer in a zinc-sufficient population," Abnet commented. "It's possible that once you get above a certain threshold, tissue zinc levels are no longer associated with cancer risk."