Alcohol and breast cancer

Many studies have linked alcohol as a cause of breast cancer as well as a range of other common cancers including upper gastrointestinal tract, and liver.

Alcohol consumption is increasing in many countries including NZ.

Young women are drinking more and binge drinking in particular is more common.

How does alcohol increase breast cancer risk?

Alcohol is broken down in the liver by various enzymes. Alcohol dehydrogenase / Aldehyde dehydrogenase / cytochrome p450.

The main metabolite of alcohol is acetaldehyde which is known to cause cancer changes in cells.

Alcohol can also directly damage the liver resulting in impaired liver function. The liver is the main chemical processor of the body. This activity includes metabolising oestrogen. When the liver is damaged oestrogen levels rise and these high levels are associated with increased breast cancer risk

Liver damage can also impair folate metabolism which in turn affects DNA synthesis and repair.

Folate supplementation may reduce this effect.

Alcohol may directly stimulate VEGF (vascular endothelial growth factor) A laboratory study has shown that alcohol increases levels of this growth factor which in turn is associated with rapid growth of tumours.

Women who drink alcohol while on HRT increase their risk even more as there seems to be an additive effect.

Reducing alcohol intake or avoiding alcohol completely can reduce the risk of breast cancer.

Studies have shown that 1 standard drink per day increases breast cancer risk by 10%. More than 3 standard drinks per day increases risk by 30%.

What is a standard drink?

Different units are used in different countries and this can cause confusion when looking at studies or discussing recommendations for safe use.

In the UK I Unit is 8g of alcohol.
In the rest of Europe 1 Unit is 10g
In the USA 1 Unit is 12g

What type of alcohol?

It does not appear to matter what type of alcohol is consumed. It is the total quantity of alcohol that is relevant.


If consumed at all limit alcoholic drinks to one per day for women and two per day for men.

It is essential that we get the message out to young women in particular that drinking excessively is harmful to their health.


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