The answer is yes, but the increase in risk is dependent on the amount of alcohol that you drink per week on average. But the devil is in the details.

This picture explains it best.

The more you drink, the higher the risk is. If you drink a small amount of alcohol, then the increase is low, around 5% to what it was (121 women out of thousand who drink vs 116/1000 who do not drink). But the increase is more pronounced with higher levels of alcohol drunk. For those women who are heavy drinkers, the risk has almost doubled from 116/1000 to 186/1000).

Alcohol increases the risk of breast cancer through several mechanisms:

1. Breakdown of alcohol to acetylaldehyde which is a toxic chemical that can damage DNA and proteins in our body

2. generating oxygen reactive species that are known to damage DNA, proteins and lipids

3. Increasing blood levels of oestrogen

4. Impairing body's ability to absorb and break down nutrients

Interestingly, breast cancer recurrence is not affected by increased alcohol consumption. And some studies show that survival is not affected by increased alcohol intake, while others show that modest alcohol intake is associated with improved survival in women with breast cancer.

​Is this also valid for women who are already at higher risk of breast cancer, like BRCA carriers?
So far there is no evidence that an increase in alcohol intake in these groups of women is associated with increased risk of breast cancer.

The reason for this could be that studies including these women include a small number of women and that the slight increase in risk (like 5%) is not found to be statistically significant. The other reason is that these women often have Er- cancers and alcohol have effects on oestrogen levels in the body, and as these cancers are oestrogen -ve, the alcohol intake will not have an impact in these women.

What I also find interesting is that increasing alcohol consumption is associated with increased mammographic breast density. This can lead to decreased detection of breast cancers by mammography. To me, it also shows that alcohol has an effect on the breast tissue. I believe that more studies are needed to look into how alcohol affects breast tissue.

So, in the end, my recommendation is that alcohol intake of around 1 standard unit per day or less is not associated with a significant increase in breast cancer risk.

Enjoy life. Would love to hear what you think.