From Pam Stephan,
Your Guide to Breast Cancer.
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About.com Health's Disease and Condition content is reviewed by V.K. Gadi, MD

Estrogen is a hormone that fuels 80% of all cases of breast cancer. Any kind of alcohol that you consume may change the levels of female hormones, and thus cause more cases of estrogen-receptor positive breast cancer, according to Dr. Yan Li, a researcher at Kaiser Permanente. Dr. Li says, "It makes no difference if a woman drinks wine, beer or liquor -- it's the alcohol itself and the quantity consumed." So what about those heart health benefits found in red wine? Turns out the flavonoids and antioxidants, not the alcohol, protect your heart’s blood vessels. So you could drink alcohol-free red wine, protect your heart, and lower your risk of breast cancer at the same time. Not a bad deal!

How Much Alcohol Is Safe?
One serving of alcohol, or one drink, is defined as:

• 12 ounces of regular beer
• 5 ounces of wine
• 1.5 ounces of 80-proof liquor

For women, one drink of an alcoholic drink per day raises your risk very slightly. Your risk of developing breast cancer goes up to 10% if you have two drinks a day. If you consume three drinks daily, your risk rises to 30%. That risk equals smoking a pack of cigarettes a day, or using hormone replacement therapy (HRT). Half a serving of alcohol a day is safe, while eliminating alcohol is the safest way to go.

How Alcohol Affects Estrogen and Progesterone Levels
Your female hormone levels fluctuate with your menstrual cycle, and change with age. Adding alcohol to the mix causes your estrogen and progesterone levels to rise. Regular drinking exposes your breast tissues to higher levels of estrogen, which can activate estrogen-sensitive breast cells to become cancerous.

Don’t Drink Alcohol If You:

• are addicted to alcohol
• may become pregnant
• are pregnant and breastfeeding
• are a child or a teenager
• are taking any drugs that interact with alcohol
• have a medical condition that is affected by alcohol (dementia, liver disease, ulcers, etc.)

Women, Alcohol, and Breast Cancer Risk
Heavy drinking is clearly linked to an increased risk of developing breast cancer. Three or more servings of alcohol per day gives you the same risk as a pack of cigarettes a day, or using hormone replacement therapy (HRT). Each of those behaviors raises your risk of breast cancer by 30%. Seventy thousand women of many races participated in Dr. Li's study, and regardless of the type of drink they preferred, those who had three or more drinks a day developed estrogen-receptor positive breast cancer. Red wine does appear to have protective benefits for heart health, by lowering LDL cholesterol and preventing blood clots. Limit your daily serving of wine to half a glass, or 2.5 ounces, and you’re in the safe zone. Better yet, try alcohol-free wines or juices for heart health.

Evidence of the Link Between Alcohol Use and Breast Cancer