The evidence is stronger than ever that being overweight or obese increases the risk for kidney cancer, according to a report we released today. It’s the key finding in the latest update from our ongoing systematic review of the global research, the Continuous Update Project (CUP).
Today’s report reaffirms the conclusion of our previous report, making kidney one of ten cancers now strongly associated with overweight and obesity. You can read the key findings here.
Among those findings, you’ll also find a new conclusion with alcohol. Here’s what we can say about alcohol and kidney cancer: it’s complicated.
Alcohol is known to be a potent carcinogen, and has been definitely linked in previous reports from AICR and WCRF International to greater risk of cancer of the mouth, pharynx and larynx, esophagus, liver, colorectum, and breast. This is why AICR recommends that if people choose to drink at all, they limit their consumption to 1 drink/day for women, and 2 drinks/day for men.
But when our CUP panel examined recent evidence from 8 studies, they found that moderate amounts of alcohol (about two drinks per day) were associated with lower risk for kidney cancer.
How can this be, when the evidence on other cancers so consistently marks alcohol as a risk-increaser?
The answer offers an intriguing reminder that cancer isn’t one disease but many, and that the risk factors associated with different kinds of cancer differ as well.
Kidney cancer is an outlier in this regard, a special case. It’s been shown, for example, that moderate consumption of alcohol lowers risk for type 2 diabetes and hyperinsulinemia, both of which are associated with kidney cancer. It’s also possible that compounds in alcoholic drinks called phenols play some protective role. And because alcohol is a diuretic, it may be that kidney cells spend less time in direct contact with carcinogens because these dangerous compounds get flushed from the body before they can do harm.
But none of this changes AICR’s take-home advice to limit alcohol, if you choose not to avoid it completely. When you consider that it raises the risk of so many other cancers, most of which are much more common in the U.S., the modest protective effect seen with kidney cancer is no argument for drinking.