Female hormones may affect risk of stomach cancer

By Will Boggs, MD

NEW YORK (Reuters Health) - Women who have been fertile for a higher than average number of years, which occurs when menstruation begins early and menopause begins late, seem to be protected to some degree against developing stomach, or "gastric" cancer, according to a report in the journal Gut.

"Hormonal factors may affect gastric cancer risk," Dr. Neal D. Freedman told Reuters Health, "but future studies are required to determine whether or not this is the case."

Freedman from the National Cancer Institute, Rockville, Maryland, and colleagues examined the association between reproductive and menstrual factors and gastric cancer risk in a large study of 74,442 women from Shanghai, China.

Later age at menopause was associated with a markedly reduced risk of gastric cancer, the researchers report, and so was increased duration of fertility.

On the other hand, increased years since menopause and intrauterine device (IUD) use were associated with an increased risk of gastric cancer.

Number of children, breast feeding, or oral contraceptive use had no bearing on the risk, the report indicates.

"Our results were consistent with those of previous studies in other countries," the investigators say, and are "consistent with the hypothesis that hormones such as estrogen and progesterone protect against the development of gastric cancer in women during the reproductive years."

"In future studies, we plan to directly test this hypothesis by determining whether...hormone levels predict gastric cancer risk," Freedman said.

SOURCE: Gut, December 2007.