PBS reports “Bacon, hot dogs, and processed meats cause cancer, as dangerous as smoking”. The article itself isn’t entirely terrible, but the headline is really poor.
To get some things out of the way:
- This isn’t really news, the WHO has rated processed meat as problematic for a few years.
- You probably should eat less red and processed meats anyway, if you are an American.
- Yes, it’s pretty likely that red meat contributes to cancer rates.
- Yes, it’s pretty likely that processed meat contributes to cancer rates.
- No, this is probably not a case of “science is telling me something else is bad and they’ll change their minds in two years”
First note: the WHO studies international health data. The overall risk of any potentially hazardous human behavior that the WHO studies needs to take that into account. Health standards vary by country, and what might be very hazardous in one country… say, drinking raw milk in sub-Saharan Africa… might be fairly safe in another, like the U.S. So there’s that. In the case of “processed meats”, you have a particularly wide variation of definitions.
But we’ll let that pass for the moment…
Let’s take a quick gander at some numbers that are relevant to the United States. Lung cancer has the third highest mortality rate of major cancer types. You have an 83.4% chance of shuffling off your mortal coil with lung cancer within five years of your diagnosis. Colorectal cancer, on the other hand, has a five year mortality rate of 33.5%. This alone is a pretty significant difference.
About 8% of lung cancer is caused by inherited factors, compared to 20% of colorectal cancers. This means that direct comparisons of these two cancer rates in randomized populations, while great for medical research, will give you a limited amount of perspective, as an individual who knows your own medical history, because genetics as a confounding factor is very different for the two cancer types. If you know that you don’t have a genetic predisposition towards colorectal cancer, that makes you very different from a random person on the street lacking that data bit.
The base rate is significantly different for the two types of cancer. You have about a 40% chance of getting some form of cancer at some point during your lifetime. You have slightly less than a 5% chance of developing colorectal cancer at some point during your lifetime, and a 7.5% chance of getting lung cancer (more on that in a minute).
So lung cancer has both a higher base rate, and a much higher mortality rate than colorectal cancer.
According to the report, processed meats contribute about a ~18% increase in your colorectal cancer risk if you eat 50 grams a day. Since your base rate of colorectal cancer is 4.34%, your adjusted risk would be 4.34% * 1.18, or… about 5%. That doesn’t sound too bad, does it? That’s assuming you eat a couple of slices of bacon every day.
On the other hand, if you smoke, you’re 15 to 30 *times* more likely to get lung cancer alone than a non-smoker. In the U.S., that factoid is estimated at an increased risk of 25 times. Studies in other countries break down lung cancer risk by smoking prevalence.
In one European study, for example, researchers found that your actual cancer rate for non smokers was under 1%, whereas the cancer rate for smokers was up to 16%. Meaning… really, you have very little chance to get lung cancer at all if you don’t smoke, and a fairly significant chance of getting lung cancer if you do smoke. Smoking also contributes to esophageal cancer, lip and mouth cancers, and other types of cancer.
Not to mention the fact that smoking is also a major contributor to heart disease, lower respiratory diseases, and stroke, as well as cancer, and that these four factors are four of the top five killers when it comes to human beings, responsible for a whopping 1,474,169 deaths in year in the United States. Smoking is terrible for you in lots of ways.
That doesn’t make bacon anywhere near “as dangerous as smoking”. Even if they are rated in the same class of carcinogens.
(Image credit: The Culinary Geek on Flickr, Creative Commons)
Updated (13:29 26-Oct-2015) to add:
On the upside, we are starting to see an increasing amount of explanatory reporting when bad science reporting hits the Internet! There is hope for the future.
Whew!
[fills corncob pipe with bacon, lights it up]Report
Ah statistics & context, what kind of BS can’t you spin with them?Report
Duuuuude,
We should be ENCOURAGING people to eat this stuff. They die sooner. That combined with limited medical treatments to folks who have these cancers, ’cause it’s their own fault for not eating healthy, we’ll save MASSIVE amounts of cash which we can then use to cover more people so they can get dental and eye care from the ACA. See how it all works?!Report
Hitler was a vegetarian who went on to commit suicide.
If we start extrapolating out from that, there are many conclusions we can reach.Report
Dude, be careful. Everybody who confuses correlation with causation ends up dead.Report
So does everyone else.Report
Right, so it’s not correlated. No worries then.Report
All I know is that, no matter what I’ve done, *I’ve* never ended up dead.Report
There’s pretty much a 1:1 correlation between living and one day being dead, so I wouldn’t get too complacent.Report
If more people are alive today than have ever died, isn’t that claim false on its face?Report
But that’s not the case. The dead far outnumber the living. It’s only a matter of time until our numbers are up too, buckaroo.Report
If more people are alive today than have ever died, isn’t that claim false on its face?
Well, only a small fraction of the people who’ve ever been born are alive today, but even if that were true, the correlation is with death: everyone who has ever died was alive before they died. 1:1.
Of course, the real test is whether death turns out to be grue.Report
everyone who has ever died was alive before they died.
We can’t possibly be sure of that.Report
I just took a quick poll on Facebook, and that doesn’t appear to be true. In fact, *no one* appeared to be dead, although obviously some of them could be lying.Report
Yeah, you can’t trust self-reporting.Report
“In order to measure the accuracy of self-reporting, we asked 300 undergraduates to rate the accuracy of their self-reports on a scale of 0 to 100, with 100 being the most accurate.”Report
This is the greatest thing on the Internet this week.
It even beat out Troublesome Frog’s “Everybody who confuses correlation with causation ends up dead” which was the previous greatest thing on the Internet this week.Report
I’ve been trying to work “Everybody who confuses correlation with causation ends up dead” into a hardboiled noir PI riff but have so far failed.Report
Not to mention how unreliable online polls are.
Tell me, what is the margin of error for your poll?Report
Past performance is no guarantee of future results.Report
@burt-likko
That’s what she said….Report
The title of this piece is redundant.Report
Now that we are aware that press articles on WHO typically are misleading, we won’t get fooled again.Report
Ooooooooouuuuuch.Report
No one knows what it’s like to be the bad science reporter.Report
For once, the problem here lies not with the Boomers or the Millennials, but with my generation.Report
The WHO should be able to conclude that the only cause of death is drug abuse.Report
The WHO are deaf to most criticism.Report
That’s why I can’t explain it to them.Report
Yeah I was seriously considering buying some steak in honor of this announcement.Report
Nuance doesn’t get enough eyeballs. It always has to be “FISH YOUR PLEASURE!! EAT NOTING BUT SPINACH OR YOU WILL DIE MISERABLY!!”
Eh, I don’t deny the unhealth of the average diet, or of mine. Though when I was doing as close to the right things as I’ve ever done is when I ended up having to fight off the C. I’ve since decided that if DNA is that unpredictable, I’m just going to enjoy what I have left and not care. Death is going to suck anyway, why should life suck too?Report
Spinach? That shit’ll kill you. It’s kale and quinoa if you want to live forever (this week, anyway.)Report
I have a container of quinoa pilaf sitting on The Arsenal (my pantry outside of the pantry). Was a gift I haven’t had use for yet.
(…I’m tempted to cook it in a pork broth)Report
This comes to mind: http://www.smbc-comics.com/?id=1623Report
Thank you Patrick. Like most Americans, I would like to interpret your argument in a beneficial way towards my current behavior and not eat 8 hot dogs.Report
I take as a baseline assumption that any journalism that involves percentages, and especially comparing percentages, will be a complete botch. Because math is hard, don’t you know? We can’t be expected to keep straight what we are comparing.Report
I figured someone around here would be writing about the latest “Hot Hand” news.Report
We are undoubtedly streaky, but basketball is the worst domain to look at, because there’s so much noise (related, e.g., to the bounciness of the ball). Better to look at golf putts or dart throwing, say. Full geek.Report
I had not seen that yet. Thanks for the tip. But big picture here. SABR (the Society for American Baseball Research) is divided into the stats camp and the history camp. I don’t think it is any secret that I am solidly in the history camp (19th century ghetto, over by the latrines). I respect the stats side. They have done impressive work, and my understanding of the game is improved by it. I am happy to eat the sausage, but I am not qualified to make it, or even to discuss how it is made.Report
Or inflation. Try reading some of the economic reports and the ridiculous comparisons they make, because nobody bothers to index to inflation, GDP growth, or population growth.
Of course, politicians do that too. (“We increased school spending 5%! What are you complaining about? Well, enrollment is up 10% and so we sorta have a problem here….”)Report
You can never shit enough on science journalism, but this story was covered admirably in The Atlantic by Ed Yong. Strength of evidence vs. degree of risk is probably the most important and misunderstood concept in scientific reporting.Report
That piece is linked in the “edited to add”.
I’ve seen a good dozen articles explaining the difficulties with the original reporting, so yay!Report
In this article, you mentioned that smokers are 15 to 30 times more likely to get lung cancer than a non-smoker. But according to the CDC website, statistics show that nonsmokers who are exposed to secondhand smoke have a 20%-30% chance of developing lung cancer. It also shows that secondhand smoke causes more than 7,300 lung cancer deaths among U.S. nonsmokers each year.Report