This subject popped up in the "Off Topic" forum thread, "The dumbest Stuff of Herald Headlines (& other new media).
The same or similar headlines and news articles appeared on numerous news sites, more or less along the lines that if you eat red meat or drink alcohol, then you're at grave risk, exacerbated by the articles stating in a very clickbaity and imprecise way, that every drink you have increases your CRC risk by 8%.
FWIW, I found the original journal article here:
I had a quick read of it last night, it seems legit, and it was a large study.
They attempted to eliminate confounding factors, those assumed factors seemed to be mainly or entirely dietary related. Fair enough I suppose given the title.
One non-dietary confounding factor which is probably missed is physical exercise, more exercise probably reduces risk considerably. I have no idea if people who eat more (red) meat tend to exercise less, (high) BMI seems to be risk factor and was included, it also loosely correlates with increased red/processed meat consumption etc.
Note that there's separate data for red and processed meat, just red meat, and just processed meat. IIRC although the study showed both were a similar risk factor, the quantity of processed meat consumed was half that of "red" meat. (50g/day vs 25g/day) for about the same increased risk.
They used self-reporting of diet - what was eaten and how much. I've no idea how accurate that was, there was mention of some methodology to reduce self-reporting error. I've no idea how much error there is in self reported diet. They did also include self-reported alcohol intake. People do tend to lie... err "underestimate" their consumption. If they'd included physical exercise, then people tend to over-report how much they get. I'd have liked to see sugar (sucrose) intake included.
Some weird results:
Drinking 3 cups of coffee a day seems to reduce incidence of CRC by 10%. Yay - now that's really got clickbait headline potential.
Quantity of fruit and vegetables consumed seems to offer no protective benefit. That's really not what the 5+ a day folks keep telling us.
Conversely, fibre from grains does seem to be moderately protective. Hmmmm.
Beer's worse than wine, apparently. For every 10g of alcohol per day, then if that's from wine, risk increased 5%. If it's beer, then risk increased 11% (8% average). I'd guess there may be gender bias in that, though the same has been reported elsewhere.
There's "heterogeneity" by gender. Probably actually the most interesting thing of all, IMO. CRC risk seems to increase significantly for men who consume red/processed meat and/or alcohol, but they report a null result for women consuming the same. There's a few hypotheses presented in an attempt to explain that.
In the end, it's probably fair to say that beef and bacon burgers - washed down with a pint of beer - isn't what a bloke should be consuming as a staple diet. OTOH a women could eat the burger, have a glass of wine daily, and so long as they ate their high fibre brekky cereal, then they're probably not at increased risk for CRC.