What do you think about the findings that rare and medium-rare beef drastically increases the risk of colorectal cancer?

You can get statistics to prove anything. This is no more and no less accurate than a thousand earlier studies.

I won’t change my eating habits because of it.

I suspect this thread will be filled with defensive rejections of this study based on some belief that science is a useless exercise that seems to produce nothing but contradictory results year after year. We should also see a dearth of links to the previous studies that have shown us that eating beef (and rare/medium-rare) decrease risk of colorectal cancer. The reaction to the other recent meat thread smacked of “now they telling me that cigarettes are bad for me? I’m not going to change my habits. Tomorrow scientists will tell us again how good they are for me.”

You may find this of interest.

@LostInParadise – Not sure if the “you” means me. That link, while interesting, talks about our evolution. It is not a study (or one of “a thousand earlier studies”) that says anything about colorectal cancer risk.

You can have my medium-rare steaks when you pry them from my cold, dead, cancer-ridden colon.

^ I’m with @GladysMensch. I eat red meat rarely enough (ha!) that I’m sure it won’t matter how I like it… but I like it rare. There’s no point eating a well-done steak.

I didn’t read the article, but I find it amusing that the risks are deemed high for rare and medium rare here… yet we also know that char is a carcinogen. Damned if you do…

May be a case of you are damned if you do damned if you don’t as I have heard cooking meats over high heat causes HCA’s to form and are just a problematic if not more than the viruses in undercooked meat.

wiki had some info on this…

Several studies published since 1990 indicate that cooking meat at high temperature creates heterocyclic amines (HCAs), which are thought to increase cancer risk in humans. Researchers at the National Cancer Institute found that human subjects who ate beef rare or medium-rare had less than one third the risk of stomach cancer than those who ate beef medium-well or well-done.[17] While eating meat raw may be the only way to avoid HCAs fully, the National Cancer Institute states that cooking meat below 212 °F (100 °C) creates “negligible amounts” of HCAs. Also, microwaving meat before cooking may reduce HCAs by 90%.[17] Nitrosamines, present in processed and cooked foods, have also been noted as being carcinogenic, being linked to colon cancer.

Research has shown that grilling, barbecuing and smoking meat and fish increases levels of carcinogenic Polycyclic aromatic hydrocarbons (PAH). In Europe, grilled meat and smoked fish generally only contribute a small proportion of dietary PAH intake since they are a minor component of diet – most intake comes from cereals, oils and fats.[18] However, in the US, grilled/barbecued meat is the second highest contributor of the mean daily intake of benzo[a]pyrene at 21% after ‘bread, cereal and grain’ at 29%.[18]

Baking, grilling or broiling food, especially starchy foods, until a toasted crust is formed generates significant concentrations of acrylamide, a possible carcinogen

Dangit, we can’t win for losin’! I guess I don’t eat red meat often enough for it to be an issue. I like my steaks grilled, broiled or fried medium rare and my roast beef to be oven roasted. That pink throughout answers a primal need for me. Yet another study isn’t likely to get me to alter my consumption of red meat. I’d guess that I actually eat a steak or roast 2–3 times a month. I may get a hamburger the same amount, so, meh.

I don’t want to say that these statistics are meaningless, but to put it into some context:

The adult population of the USA is approximately 200,000,000 people.
According to the National Cancer Institute the estimated cases for colon + rectal cancers in the USA for 2012 will be around 143,000 (from the page referenced above). This is a colorectal cancer rate of approximately 0.069%, a very low rate of incidence. (The rate of death from this cause is about ⅓ of the total incidence rate.)

If that incidence rate were to be increased by 30% (which is a significant rise, no doubt!) then the rate of incidence would be around 0.090%, which is still a low rate of incidence.

The study is significant, but based on the low overall rate (and the fact that I don’t eat beef all that much anyway, but I do like me a medium rare steak!) I don’t see any need for change in my own diet.

I know it’s probably awful, but I just don’t even bother myself with thoughts about what foods increase/decrease cancer risk. It seems like there’s a new study every day saying to avoid certain foods, and being an underweight person I’m not really in a position to deny myself too many food options.

As for this particular study, I don’t have a colon or a rectum, so colorectal cancer doesn’t scare me too much. :)

Um… where’s the data about how much meat you need to consume in order to exhibit this effect?

@CWOTUS I tend to lean the direction you are in that there are many other mitigating circumstances that could contribute to these stats. What about the life styles and dietary habits of red meat eaters?? It could vary widely between the rare beef eaters and the charred beyond recognition meat eaters. Plus there is no indication of the amount of beef consumed. Are we talking 18 ounce porterhouses or 4 ounce beef patties? Not enough info to get excited over.

@elbanditoroso – Are you able to explain the difference between mere statistics and the setup and conclusions of scientific studies? I think that’s important.

A while back there was a large study done, I need to try to search for it some more, that higher fiber diets with less red meat showed no significant reduction of colon cancer as had been claimed previously. At best I would say there are very conflicting studies on the idea.

Now, about this study, I have several questions and thoughts. First, they are looking at different geographic regions with various different gene pools and cultural norms. The only way to try to narrow down if it is food related is to do a study with people of those descents when they do consume rare beef, and live in countries that have higher incidents of colorectal cancer.

I also would want to be sure what type of cancer they are talking about. Is it HPV related? That might have to do with cultural mores more than food.

Lastly, those who eat rare beef, might be more likely to eat processed foods as well, more foods with more chemicals in general.

@LostInParadise – Thanks for the link. I’ve read similar articles. And just to be clear, I’m not advocating vegetarianism here. I do eat meat, although less than in the past, because eating too much meat is like driving a gas-guzzling SUV. The issue here is linking viruses to cancer, as already proved for human papilloma viruses and cervical cancer. In the German article it was mentioned that beef should be heated to at least 158 F to kill all viruses suspected of causing colorectal cancer or increasing the risk of colorectal cancer.

@Cruiser – It’s not one or the other. It’s possible to heat up meat without creating nitrosamines as can happen for barbecued meat.

@CWOTUS – The interesting part is what happened in South Korea. Harald zur Hausen is a Nobel Prize winner of medicine and we can’t dismiss his research as yet another meaningless statistic. Before he went public and wrote the article he analyzed more than 100 studies worldwide and conducted several on his own. One candidate he mentions is the so-called TT virus.

I’m not saying people should change their diet, but being aware of risks is a good idea. If people eat one large rare steak every other day it might be worth reconsidering. If people live in a city with heavy traffic near their house it might make sense to get better windows to lower the noise. An occasional trip to a loud city isn’t a big deal.

@wundayatta – I don’t have access to the medical article. I searched some more, but there seem to be no free articles about the issue. What I also found is this:

“Current estimates hold that 21% of all human cancers are linked to infections. But some experts believe this figure is too low and is headed substantially higher. Dr. zur Hausen is particularly attracted to the possibility that cattle may play a role in some human cancers. He hypothesizes that some as-yet unidentified bovine virus, which is nononcogenic in its normal host, can become carcinogenic when transmitted to humans. Multiple lines of circumstantial evidence support this notion. For example, basal cell carcinomas are known to have a predisposition to arise in smallpox vaccination scars. Smallpox vaccines were prepared by inoculating vaccinia virus into the skin of calves and then harvesting the crusted skin, which could in theory contain contaminating bovine viruses. Also, colorectal cancer, and to a lesser extent breast cancer and lung cancer in nonsmokers, have repeatedly been associated with beef consumption in epidemiologic studies. Countries with high consumption of goat or pork have relatively low rates of these malignancies. The observed link between a red meat–rich diet and increased rates of colorectal and other cancers is often attributed to the formation of aromatic hydrocarbons and other known carcinogens during cooking or meat curing. But Dr. zur Hausen believes this interpretation might be inadequate. He noted that grilled, fried, and smoked poultry contain similar concentrations of these carcinogens, yet heavy consumption of poultry hasn’t been associated with an increased cancer risk.”

http://www.oncologyreport.com/index.php?id=6016&type=98&tx_ttnews[tt_news]=78446&cHash=da03e20e36

@JLeslie – Yes, as far as I understand it Harald zur Hausen has dealt with the issue of different gene pools and cultural norms. Of course we need to rule out other potential causes that correlate with high beef consumption.

Well, I heard there was an amount involved, but I don’t remember what I heard. Maybe three ounces of meet two or more times a week. Not sure.

I enjoy my steak blue but seeing as I have steak (or any red meat for that matter) maybe once every six months, I am not too concerned. I am happy to take every study on board but I am not going to become paranoid. Everything in moderation.

@mattbrowne Do you know if he looked at underlying cause? someone is not going to get HPV related rectal cancer unless they are having anal sex, or some other way to introduce the virus. I think nutrition and overall health can contribute to if it becomes cancerous. Honestly, I am very interested in stats on HPV related cancers, so that is affecting my answers on this q. My brother-in-law was diagnosed with rectal cancer a few weeks ago. The tumour is six centimeters. That seems scary large to me. The doctor said one more month and his rectum would have been completely blocked the cancer is growing so aggressively. I guess part of it is cancer must grow exponentially I assume. The bigger it is the faster it grows? That is my assumption anyway. I asked him if it was HPV related, I don’t know if he knew what I meant, he answered “no” and I did not want to push it, he is going through enough. He is gay. It freaks me out, because I think women should be regularly tested during their GYN exams, tongue and anus, if they are at risk, and men should have the testing available as well of course if they believe they are at risk.

I don’t trust at all that the doctor said anything or testing anything regarding HPV or not. 15–20 years ago most of my friends with cervical dysplasia or cancer had no idea they catch it from their boyfriends. I only had one girlfriend who was told by a doctor way back in the mid 80’s, she was the first person to ever tell me about the relationship between HPV and cervical cancer, her medical care was through our military. Now with the HPV preventative vaccine there is more awareness, but for some reason people don’t extrapolate and figure out it is true for other areas of the body, I think even doctors are clueless. It’s logical it would cause disease and cancer on other parts of the body with similar tissue, one does not even need a scientific study or proof to at least make a good hypothesis about it. Of course, there is scientific proof, but even if there wasn’t.

I’m always wary of retrospective epidemiological studies like this. Correlation does not equal causation.

@JLeslie – Yes, as far as I can tell he did. He suspects a virus, perhaps the TT virus. It was all done in controlled studies. Controlling for variables was key, because rising standards of living leads to all kinds of behavioral changes. I’m not sure about exponential growth of cancer being always the case.

@Rarebear – Correlation does not always equal causation. But it did for the papilloma virus and cervical cancer. This is why we have a vaccine for women.

@mattbrowne, I can send you a pdf of the full text if you send me your email address.

@wundayatta, this study does not specifically address the amount of meat consumed; you are thinking of another one that came out recently.

@mattbrowne Matt, that’s a logical fallacy and you know it.

@Rarebear, I disagree. Again, you are referencing correlation when there was not actually a single correlation performed in the study. And as I explained before, correlations are fraught with interpretive problems to precisely the same extent as every other parametric statistic. Brushing off statistics because they’re correlative makes no more sense than throwing out a study just because it’s an ANOVA—and it makes even less sense when no regression analysis was even done!!!

@nikipedia The BBC has a good article on the study you mention that clearly explains the risk of eating a little extra red meat every day. This article says it would take one year off the life expectancy of a 40 year old. It also says that the link between eating red meat and cancer may be a coincidence although the findings are in agreement with other such studies and they did try to rule this out.

Of course it’s a logical fallacy.
If a = b, does not necessarily mean c = d

I’m not brushing off the statistics or blowing off the study. I’m saying that just because you have a correlation does not necessarily mean causation. You need corroborating evidence.

It very well may be true that red meat causes colon cancer. But this is so heterogeneous, and diets are so heterogeneous, and there are so many confounding factors that it’s a very difficult conclusion to make—especially if you start using logistical regression analyses.

HPV causing cervical cancer is much simpler. You either are infected with HPV or you’re not.

I completely agree that one study standing on its own is meaningless, no matter how small the p value or how big the eta squared. Cautious interpretation and robust replication are essential to the scientific process.

All I’m saying is that correlations have exactly as much explanatory power as any other commonly used statistical test. The quote that “correlation is not causation” is a widely misunderstood oversimplification of statistics.

[mod says] This is our Question of the Day!

“I refuse to spend my life worrying about what I eat. There is no pleasure worth forgoing just for an extra three years in the geriatric ward.”
—John Mortimer

Or to put it another way, this is what I think of it. Don’t get me wrong: I don’t doubt the science, and I already eat much less meat than the average American. But this study does not inspire me to ruin steaks before eating them.

@Rarebear – My point was that some studies can show that some correlations also turn out to be causations. That’s the reason we have warning labels on cigarette packs. For decades the nicotine industry talked about correlation.

@mattbrowne Sure. Generally if there is a causation there is also a corellation. The reverse is not necessarily true, though. I saw one correlative study that someone was trying to show that was trying to prove that abortions caused breast cancer, and therefore abortions should be banned. I pointed out to her the methodological problems with the study and she backed off.

@Rarebear – Yes, the reverse is not necessarily true, but it’s also wrong to assume that the reverse is never true. So this Nobel Prize winner has a hypothesis about a virus not destroyed during the cooking process causing colorectal cancer. Now it’s up to other scientists to corroborate this or prove him wrong. I was merely interested what people thought about the rare beef hypothesis and what other sources they might know about. Other hypotheses like abortion causing breast cancer might’ve already been clearly refuted.

I never said the reverse is never true, Matt. And your example of the nobel prize winner with the cancer is also flawed. You said,“this Nobel Prize winner has a hypothesis about a virus not destroyed during the cooking process causing colorectal cancer. Now it’s up to other scientist to corroborate this or prove him wrong.”

Not exactly. The burden of proof is on the person making the assertion. The null hypothesis is that red meat does not cause colon cancer. If you want to say that red meat causes colon cancer then you need several things.

1) You need a valid scientific mechanism.
2) You need experimental proof
3) You need good epidemiological evidence—especially if #2 is not available.

You can’t just say, “I am a Nobel Prize winner and I see a correlation between red meat and colon cancer, now prove me wrong.”

Now let me be crystal clear, just so you understand my position. Cancer is an extremely complex multifactorial disease that is very VERY difficult to pin down a cause. Every once in awhile there is a Nobel-worthy discovery like HPV causing cervical cancer, but usually isn’t not that easy. I see more colon cancer than anybody here, with the possible exception of one person who I won’t name because he’s not posted on this thread, and I can tell you that although people would love to hang their hat one one thing, like red meat, sadly it’s not that easy.

Is it possible that red meat is one factor in some people as a cause for cancer? Certainly. Is it proven? By no means.

@Rarebear When you find colon/rectal cancer do they always test for HPV, and of then would you inform the patient?

@JLeslie No, HPV isn’t related, as far as I know, to colon cancer. I usually find colon cancer on colonoscopy.

Anal cancer (which is completely different) , on the other hand, is related to HPV, and if someone has anal cancer or anal dysplasia, then they would definitely get a pap smear and/or cervical biopsy.

@Rarebear – So why do we have the vaccinations to prevent cervical cancer?

@mattbrowne What? What does that have to do with colon cancer? We have vaccines to prevent cervical cancer because HPV causes cervical cancer..

@mattbrowne – I don’t understand the difference between the scientific case for the cause of cervical cancer and colon cancer. As far as I understand Harald zur Hausen used a similar approach in his studies. His findings were: HPV causes cervical cancer and the TT-virus quite likely causes colon cancer (which is more than just to say viral infections correlate with colon cancer). I guess I must be overlooking something.

Matt, you referenced yourself, I assume you meant to direct that to me.

The TT virus doesn’t “quite likely” cause colon cancer. It MAY be one factor in a large multifactoral causation and is by no means proven (and IMO is probably a red herring). Certainly it’s not conclusive, and even more certainly not enough to imply that we can develop a vaccine against colon cancer or not eating red meat will eliminate our risk.

HPV is different. With HPV the causation is clear. If you are a woman and virginal, the chance of you getting HPV is remote, and the chance of cervical cancer is even more remote. HPV vaccine, if used and not eschewed by the anti-vaccine nuts, may well eliminate cervical cancer. Again, it has nothing to do with colon cancer.

@Rarebear – Yes, sorry, my question was directed at you. And thanks for your clarification. I now understand your viewpoint based on the difference between the viruses.

@Rarebear Thanks for that info. I did not know it is only associated with anal cancer, I am very glad to know that,

HPV affects only squamous epithelium of which cervical tissue and anal tissue are. Colon mucosa isn’t squamous.

@Rarebear Do you have any thoughts on woman who are HPV positive on their cervix, and who have had abnormal tissue which needed treatment/culposcopy getting “PAP’s” on their anus and tongue? I want that done woth some sort of regularity, and I personally think GYN should do it.

Never heard of a tongue colposcopy. But I would feel comfortable going to anybody who does a lot of them.

@Rarebear Supposedly dentists are supposed to test for HPV, or change in cells, and I know mine doesn’t. I’m not sure if they do culposcopy for positive changes in the tissue in that part of body actually?