Everything we eat both causes and prevents cancer [1]. The two real questions are: What are the odds? And, where is the good balance? The linked paper says "Current estimates suggest that alcohol-attributable cancers at these sites make up 5.8% of all cancer deaths world-wide." [2] The earlier linked recommendation is basically "keep your average <= 1 drink a day" [3] But, I didn't read the details.

[1] http://www.sciencealert.com/images/art-apr-15/Medical_studie...

[2] http://onlinelibrary.wiley.com/doi/10.1111/add.13477/abstrac...

[3] https://www.theguardian.com/society/2016/jan/08/tough-drinki...