Lab mice injected with breast-cancer cells and fed the equivalent of two alcoholic drinks daily developed tumors that were twice the weight of those in mice that did not ingest alcohol, researchers said.

Fox News reported April 30 that researcher Jian-Wei Gu of the University of Mississippi and colleagues said the four-week study indicated that alcohol use increased levels of a hormone called VGEF, which stimulates growth of blood vessels, which in turn caused tumors to grow faster. Researchers said that alcohol use increases cellular activity as the body tries to rid itself of the toxin.

Gu said that genetic risks for breast cancer are unavoidable, "alcohol [consumption] is the most important avoidable risk factor for women getting breast cancer."

The research was presented at the American Physiological Society's annual meeting in Washington, D.C.