Your risk does not rise 18%, as in from 5% to 23%, but 18% of your existing relative risk.
Your existing relative risk as an American (not as an individual) is 5% (compared to non-Americans).
18% of 5% is .9, hence your risk rising (relatively) from 5% to 6%.
By eating processed, factory-farmed meat (there was no distinction of source, obviously). If you are American. With no consideration of the rest of your diet, lifestyle, genetics, location, demographics, etc. Or even, really, all that much of a distinction between causation and correlation.
With red meat, btw, there is too little evidence to even come up with numbers like these.
Check this out for a solid discussion: Latest in Paleo 146: Red Meat, Cancer, and WHO?
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