Why alcohol boosts breast cancer risk: study

NEW YORK (Reuters Health) - A study in mice shows that moderate alcohol consumption stimulates the growth and progression of breast cancer by fueling the development of new blood vessels -- a process called "angiogenesis." It does this by boosting expression of a key growth factor known as vascular endothelial growth factor or VEGF.

Drinking alcohol -- even moderate amounts - is a well-established risk factor for breast cancer in women. A recent study found that 60 percent of breast cancer cases in women worldwide were attributable to alcohol consumption. But the mechanism(s) of alcohol-induced breast cancer are poorly understood.

Dr. Jian-Wei Gu and colleagues from the University of Mississippi Medical Center in Jackson examined the effects of alcohol on tumor growth and progression of breast cancer in mice.

For 4 weeks, 6-week old female mice consumed regular drinking water or water containing 1 percent alcohol, which is equivalent to about 2 to 4 drinks in humans. In week 2, the animals were inoculated with mouse breast cancer cells.

"We found after about 4 weeks that breast tumor size almost doubled in mice that drank alcohol compared to control mice given plain water," Gu noted in a telephone interview with Reuters Health. Moderate alcohol intake also caused a noteworthy increase in tumor blood vessels compared with no alcohol intake.

The team also observed a significant increase in VEGF levels in the tumors of mice consuming alcohol compared to the tumors of control mice.

"VEGF can promote the formation of new blood vessels," Gu said. "This suggests that alcohol can induce tumor angiogenesis."

He presented the research at the American Physiological Society's annual meeting, part of Experimental Biology 2007, underway in Washington DC.