From the journal Addiction, “Alcohol consumption as a cause of cancer“:
Background and aims: There is increasing research evidence about the causal role of alcohol in cancer, accompanied by unclear and conﬂicting messages in the media. This paper aimed to clarify the strength of the evidence for alcohol as a cause of cancer, and the meaning of cause in this context.
Methods: Recent epidemiological and biological research on alcohol and cancer was reviewed and summarized, drawing upon published meta-analyses identiﬁed from the Medline database and the archives of the International Agency for Research on Cancer. More recent epidemiological studies not included in these publications were also reviewed. A brief description of the nature of causal inference in epidemiology was used to frame discussion of the strength of the evidence that alcohol causes cancer, and contrast this with the case for a protective association of alcohol with cardiovascular disease.
Let’s start with the fact that this wasn’t a new experiment. It wasn’t a new meta-analysis. It was a review article. It had no methods section. It’s very much like an opinion piece.
Does that mean we should ignore it? No. But I have to be honest: I knew even before I read it that it was unlikely to change my mind. That’s because I’ve already looked at all the literature and studies for alcohol. There’s no new study here.
The author argues that there is strong evidence that alcohol causes cancer in seven sites. As I noted in my Upshot piece, there is evidence that heavy drinking is associated with a number of types of cancer. Heavy drinking is TERRIBLE. But that’s not the same as saying that alcohol is terrible for you, full stop.
The author notes that some cancers (like breast cancer) show an association even with less amounts of alcohol. I agreed in my Upshot column. I also noted that each additional drink per day increases the relative risk by a statistically significant, but small, 2 percent — although not the absolute risk. That’s very small, and should be weighed against other benefits.
The author also dismisses any benefits with respect to heart disease. I don’t think the evidence makes that easy to do, as I’ve discussed repeatedly. I know about the limitations of epidemiologic research.
I’d also point out that randomized controlled trials do exist, which the author doesn’t cite. I discussed them in my original Upshot column.
The take home message here is that this is a review article, not a systematic review, and as such, I wouldn’t have even included in as part of my literature reviews (here’s why). This doesn’t change anything much for me at all. Regardless of what the many, many media stories covering it say.