One result was an estimated 13000 additional abortions the following year in England and Wales.
Another was, ironically, a lot of thrombosis cases - pregnancies and abortions are much more likely to bring on the condition than does taking a third-generation birth control pill.
Information about relative risk can be misleading, then, unless it's presented in the context of absolute risk. So what's the absolute risk of getting colorectal cancer? According to the National Cancer Institute, men 60 and younger face almost a 5% chance of getting colorectal cancer in their lifetimes, and a greater than 2% chance of dying from it. For women it's about 4.5% and 1.9%.
Colorectal cancer, then, is a relatively common and deadly disease. It tends to hit people later in life, when they're eventually going to die of something in any case. But still, it's worth trying to avoid.
Let's say you're a man, you have about a 5% chance of eventually getting colorectal cancer, and you up you bacon consumption by two pieces a day. That increases your cancer risk to almost 6% - not a trivial jump.
Unlike the ill-advised and since-revoked US dietary recommendations against cholesterol, these processed-meat cancer-risk estimates are based on years and years of empirical research. The 18% figure comes from a 2011 meta-analysis, published in the open-source journal PLOS One, of nine different studies of colorectal cancer.
It's just an estimate, and it's always possible that other things that processed-meat eaters tend to do - such as standing around grills full of burning charcoal - raise their cancer risk. Still, it wouldn't be unreasonable to make changes in your diet based on this evidence (and similar but weaker evidence on the link between red meat and cancer).
I like bacon a lot, but I'd rather have a five in 100 chance of getting colorectal cancer than a six on 100 chance. Good on the World Health Organisation for getting the world out. What I don't present the risk in those terms.