Women who drink moderate to large amounts of alcohol during pregnancy may increase a daughter's future risk of breast cancer, according to research presented at the first annual Frontiers in Cancer Prevention Research meeting conducted by the American Association for Cancer Research.

"Our earlier studies have shown that what a mother eats during her pregnancy may affect her daughter's future risk of breast cancer," said Dr. Leena Hilakivi-Clarke, professor of oncology and director of tumor biology at Georgetown University and senior investigator of the study.

Diet can increase estrogen levels, which when elevated can increase breast cancer risk by making the developing breast cells vulnerable to factors that in later life can turn them malignant. Because alcohol increases both estrogen levels in the blood and the risk of breast cancer, researchers speculated that alcohol exposure in utero could affect breast cancer risk.

Researchers fed pregnant rats moderate and high amounts of alcohol during pregnancy. The amount of alcohol was enough to raise pregnancy estrogen levels but not enough to have an adverse effect on normal fetal development.

When the female offspring reached adulthood, they were given a cancer-causing agent to spur the growth of breast cancer. Offspring who were exposed to a moderate or high amount of alcohol in utero experienced a significantly higher number of breast tumors compared with mice not given alcohol.

"Women should continue to heed warnings that alcohol intake during pregnancy should be significantly limited to protect their offspring," said Anna Cabanes, instructor in the Department of Oncology at Georgetown University and researcher.

Other sources: American Association for Cancer Research