Questionable for-profit cancer center profits from alternative therapies

It sounds like a crazy conspiracy theory: a secretive businessman founds a for-profit medical center to treat cancer.  His hospitals offer conventional treatments but also sell highly questionable, unscientific treatments to vulnerable patients. These treatments help to increase profits.  The businessman uses the profits from his cancer hospitals to support his favorite right-wing causes.  Patients have no idea that the fees they pay for treatment help support these causes.

It may sound unbelievable, but it's true.  Most of this story was described in a lengthy exposé just published in the Washington Post on Christmas day.  The Post revealed that Richard Stephenson, the founder of a large for-profit cancer center, is also one of the primary funding sources for Freedom Works, a right-wing Tea Party organization that played a major role in the 2012 elections.  As the Post story described him:

[Stephenson is] "a reclusive Illinois millionaire who has exerted increasing control over one of Washington’s most influential conservative grass-roots organizations."

Among other examples, the Post describes how

"more than $12 million in donations was funneled through two Tennessee corporations to the FreedomWorks super PAC after negotiations with Stephenson over a preelection gift of the same size....  The origin of the money has not previously been reported."

What the Post story didn't explain was the source of Stephenson's millions: Cancer Treatment Centers of America (CTCA), a private, for-profit company with five cancer hospitals scattered around the U.S.  Stephenson is the founder and chairman of CTCA.

For-profit hospitals present a big ethical problem, even when they provide proper care.  The problem is that motivation to increase profits may work against the interest of patients.  I don't want to debate that here, because CTCA has another, more serious problem.  Alongside standard, science-based cancer therapies, CTCA also offers an array of questionable, unscientific therapies, which it proudly labels as part of its "integrative cancer treatment."  CTCA advertises many such treatments, including:

• Acupuncture
• Acupressure
• Chiropractic
• Naturopathy 
• Homeopathy
• Mind-Body medicine (including Reiki and Qi Gong)

None of the treatments in this list has any scientific support showing that they provide a benefit to cancer patients.  Some of them carry a real risk of harm, as I've written about previously.  Acupuncture carries a risk of infection and chiropractic treatment has a risk of stroke - very small risks, admittedly, but no risk is acceptable when the benefit is nonexistent.  (See Science-Based Medicine for a summary of the science behind these and other alternative therapies.)

CTCA makes multiple unsupported, unscientific claims for its alternative treatments, such as:

• "Naturopathic medicine can help reduce these [cancer-related] symptoms, strengthen the immune system and support the healing process throughout your brain cancer treatment." 
• "Acupuncture may help to alleviate [cancer] treatment-related side effects, such as nausea and vomiting." 
• "When used during your leukemia treatment, our chiropractic care services can help correct bone, muscle and joint problems and restore nerve function." 

These are just a few examples. These claims, and CTCA's marketing of the therapies involved, present a huge ethical problem.  Cancer patients are facing some of the most difficult decisions in their lives, often while suffering through painful treatments, not to mention the fear that their cancer will kill them.  When a cancer hospital offers an "integrative" treatment with the promise that it may help, the patient is highly likely to try it, regardless of the cost.  These are extremely vulnerable patients, and CTCA is taking advantage of them to sell ineffective therapies.  CTCA and its owners, including Richard Stephenson, are profiting from their unsuspecting patients.

Offering treatments that are little more than snake oil to cancer patients is ethically indefensible.  Believers in acupuncture, naturopathy, Reiki, and homeopathy will argue that they are not unethical, because the treatments work.  This argument, though, flies in the face of overwhelming evidence to the contrary.  Those who argue that these therapies really work only demonstrate that they are unqualified to offer medical care.

Cancer Treatment Centers of America presents a very welcoming, positive picture of itself through its website, and much of what it describes is accurate.  However, its errors of omission are huge: nowhere does its website say that CTCA is a for-profit center, nor does it tell you that its founder is a major donor to right-wing political organizations.  And most critically for patients, CTCA offers a palette of pseudoscientific treatments, making medical claims that are not supported by any evidence and that in some cases violate basic principles of physiology and biology - although the website claims that its integrative treatments are "scientifically-based supportive therapies."

Let's put aside the right-wing propensities of its owners and simply focus on the science and the ethics of CTCA's "integrative" therapies.  Even if the treatments were free, there is no justification for offering treatments based on pseudoscience.  In the context of a for-profit hospital, where every treatment provided adds to the bottom line, the practice of pushing illegitimate treatments onto cancer patients is even more reprehensible.

[Note: the publisher of Forbes magazine, Steve Forbes, is a board member for Freedom Works.  In case it's not obvious, I don't speak for Forbes and they don't endorse the content of my blog, which appears both here and on the Forbes site.]

[Note 2: for a more detailed, critical look at some of CTCA's offerings and its claims, see this post by Orac at Respectful Insolence from mid-2010.]

Have another cup o' joe, it's good for you

My favorite science studies are the ones that tell us that what we're already doing is good for us. This story fits the bill. In the American Journal of Epidemiology this month, Janet Hildebrand and colleagues reported on a large study looking at the effects of coffee on throat cancers.

Let's get right to the good news: drinking coffee seems to reduce your risk of death from oral or pharyngeal cancer by about 50%. Drinking more coffee is better than drinking less, and drinking caffeinated (normal) coffee is better than decaf.

I knew there was something wrong with decaf.

Now for some details. This study is part of an enormous project, the Cancer Prevention Study II, with over 1 million participants who've been followed for 30 years. The participants regularly fill out questionnaires answering a variety of questions, including how much coffee and tea they drink. After excluding people with missing information about coffee drinking and those who already had cancer in 1982, the researchers still had over 950,000 people. Coffee drinking was categorized based on daily consumption: less than a cup (or none), 1-2 cups, 3-4 cups, and more than 4 cups. They asked about decaf coffee and tea drinking as well.

A study like this is hard to do well, because there are so many confounding variables, especially smoking. Smokers have a dramatically higher risk of throat cancer, and smokers also drink a lot of coffee. Hildebrand and colleagues did a good job at separating out this effect, looking at the risk of cancer in nonsmokers separately and adjusting the statistics accordingly.

Perhaps the most encouraging finding is this: in people who have been nonsmokers for at least 20 years, 1-2 cups of coffee per day corresponds to a 32% decrease in the risk of death from throat cancer.  More than 2 cups per day corresponds to a 64% decrease. And among all participants (including former smokers), more than 4 cups a day seemed to provide the greatest benefit.

Decaf coffee also seems to reduce the risk of fatal throat cancer, though not quite as much. Tea drinkers, in contrast, don't seem to get any benefit, not for this type of cancer.

All this comes with some very big caveats.  First, despite the very large size of the study, the number of deaths oral or pharyngeal cancer was very small, only a few hundred. (Oral/pharyngeal cancer is very common worldwide, but less common in the U.S., where this study was conducted, with about 7850 deaths per year. This includes cancers of the tongue, mouth, and pharynx.)  So the absolute risk is very small.  Another big caveat is that this study only looked at cancer deaths - it did not measure the risk of getting cancer in the first place.

But skepticism aside, drinking coffee seems to reduce the risk of oral cancer.  This confirms my long-held view that the three major food groups - coffee, chocolate, and red wine - are all good for you.  So the next time you feel like a second cup, or a third: drink up!

Congress holds an anti-vaccine hearing

I was in my car yesterday listening to C-SPAN (yes, I do that sometimes), when to my stunned surprise I heard Congressman Dan Burton launch into a diatribe on how mercury in vaccines causes autism.  No, this was not a replay of a recording from a decade ago.  The hearing was held just a few days ago by the Committee on Oversight and Government Reform.

Congressman Burton used this hearing to rehash a series of some of the most thoroughly discredited anti-vaccine positions of the past decade.  Burton is a firm believer in the myth that vaccines cause autism, and he arrogantly holds the position that he knows the truth better than the thousands of scientists who have spent much of the past decade doing real science that proves him wrong.  

In a classic political move, the committee called on scientists Alan Guttmacher from the NIH and Colleen Boyle from the CDC to testify, but in fact the committee just wanted to bully the scientists.  Committee members lectured the scientists, throwing out bad science claims, often disguised as questions, thick and fast.  Alas, Guttmacher and Boyle weren't prepared for this kind of rapid-fire assault by pseudoscience.

Burton himself was the worst offender, offering anecdotes and bad science with an air of authority.  He stated bluntly: 

“I’m convinced that the mercury in vaccinations is a contributing factor to neurological diseases such as autism."

No, it isn't.  Dozens of studies, involving hundreds of thousands of children, have found the same thing: there is no link whatsoever between thimerosal and autism, or between vaccines and autism.  And Burton went off the deep end with this: 

"It wasn’t so bad when a child gets one or two or three vaccines… Mercury accumulates in the brain until it has to be chelated.” 

Bang bang, two false claims in 10 seconds.  First he claims that mercury from vaccines "accumulates in the brain", a statement with no scientific support at all. Then he claims that chelation therapy is the solution - a radical, potentially very harmful treatment that no sensible parent would ever force on their child.  Unfortunately, some quack doctors have experimented with chelation therapy on autistic children, despite that fact that it can cause deadly liver and kidney damage, and one of them caused the death of a 5-year-old boy in 2005.

Burton also claimed that single-shot vials would "eliminate the possibilty of neurological damage from vaccines" - a claim that was invented out of thin air by the discredited anti-vax doctor Andrew Wakefield, whose fraudulent 1998 study was the spark that started the current wave of anti-vax hysteria.

Congressman Bill Posey from Florida was just as bad as Burton, demanding a study of vaccinated versus unvaccinated children, a standard talking point of the anti-vax movement.  (Congressman Posey: do you even realize that your question is almost identical to what Jenny McCarthy asked five years ago, on the Larry King Live show?)  Here's his question to the CDC's Boyle:

"I wonder if the CDC has conducted or facilitated a study comparing vaccinated children with unvaccinated children yet - have you done that?"

Dr. Boyle wasn't prepared for this.  She tried to point out that many studies have been done looking at the relation between vaccines and autism, but she didn't get very far before interrupted, thus: 

Rep. Posey: “So clearly, definitely, unequivocally, you have studied vaccinated versus unvaccinated?” 

Dr. Boyle: “We have not studied vaccinated versus unvaccinated." 

Posey: “Never mind. Stop there. That was the meaning of my question. You wasted two minutes of my time."

Dr. Boyle simply wasn't prepared for a Congressman who was parroting anti-vax activists.  It's too late now, but her response should have been this:

Congressman Posey, only an extremely unethical scientist would consider conducting such a study.  To compare vaccinated versus unvaccinated children in the manner you suggest, one would have to withhold vaccines from young children.  We know from decades of evidence, involving tens of millions of children, that vaccines save lives.  Few if any medical interventions are more effective than vaccines. 

But Congressman, the scientific community has done observational studies of vaccinated versus unvaccinated children, comparing autism rates in children whose parents chose not to vaccinate.  Those studies show that autism rates were slightly higher in unvaccinated children.  That's right, vaccinated children had autism at a lower rate. 

So no, Congressman Posey, the CDC hasn't done a study of vaccinated versus unvaccinated children.  Only a corrupt dictatorship could impose a study like that on its people.  Is that what you want?

To make matters worse, the House committee invited Mark Blaxill to testify.  Blaxill is a well-known anti-vaccine activist whose organization, SafeMinds, seems to revolve around the bogus claim that mercury in vaccines causes autism.  His organization urges parents not to vaccinate their children, and giving him such a prominent platform only serves to spread misinformation among parents of young children.  

Blaxill's central claim is that that we're in the midst of an autism epidemic: 

"For a long time, reported U.S. autism rates were low, estimated at about 1 in 10,000. Then around 1990 something new and terrible happened to a generation of children. Autism rates didn’t just rise, they multiplied," claimed Blaxill in his written testimony.

His entire argument builds on this.  Yet multiple studies, looking carefully and objectively at the data, indicate that all or nearly all of the rise in autism cases is due to increasing diagnoses, which in turn is due to multiple factors: a dramatically broading of the definition of autism in the early 1990s, a greater awareness of the condition, and a greater willingness of doctors and parents to accept the diagnosis.  For an objective summary of the evidence, see the articles by neurologist Steven Novella here and here, which summarize a dozen epidemiological studies.  The weight of the evidence shows that the actual incidence of autism is either stable or possibly rising very slowly.  There is no "autism epidemic."

It's also worth pointing out that Blaxill is a conspiracy theorist who claims that the "CDC has actively covered up the evidence surrounding autism’s environmental causes."  

Congress has every right to conduct oversight into medical research at the NIH and the CDC.  But when Dan Burton, Bob Posey, and others decide in advance what the science says, and abuse their power to demand "answers" that validate their badly mistaken beliefs, people can be harmed. Over the past decade, the anti-vaccine movement has successfully convinced millions of parents to leave their kids unvaccinated, and the result has been serious outbreaks of whooping cough, haemophilus, measles, chicken pox, and mumps around the U.S. and Europe.  

Some anti-vax parents claim that these childhood illnesses aren't so bad.  I wish they would talk to the parents of young children who have died in recent whooping cough outbreaks.  These illnesses can be deadly.

Message to Congress: science isn't easy, and autism is complicated.  Don't criticize science when it doesn't give you the answer you thought you knew.  That's not how science works.  Thousands of scientists are now trying to identify the causes of autism, and they've made progress, especially on the genetic front.  The answer might not be simple, but we will find it.  

Maryland puts football ahead of academics - again

It's holiday season, and here in the U.S. that means one thing: football!  Right?  I mean, what could be more important than football? 

At least that's what the president and regents of the University of Maryland seem to think.  This week, they announced that after 60 years, UMD is leaving the Atlantic Coast Conference, to join the Big Ten.  (Note to non-football fans: the Big Ten has 12 teams.  Yes, I know.)

The president of UMD, Wallace Loh, announced the deal just after the Board of Regents approved it a few days ago, in a secret meeting.  "Today is a watershed moment for the University of Maryland," he said.

Wallace Loh is an accomplished academic, but he is turning out to be a disaster for the University of Maryland.  His first action, just a month after joining the University in 2010, was to announce a wasteful $2 million buyout of the football coach, who had another year left in his contract. Eager football boosters couldn't wait to replace him, so Loh went along with that deal, spending over $2 million to bring in a new coach who, I should mention, has had two lousy seasons so far.  Not that it should matter.

Then, less than a year later, President Loh announced that he was eliminating 8 other sports teams to save money for football, basically doubling down on his big-time football bet.  Well, there goes any pretense that he's doing this for the student-athletes.

To see how deeply confused UMD's Loh is, consider what he said in his press release announcing the move to the Big Ten:

"We wanted to join this athletic conference because we also wanted to join its associated academic consortium. The extensive opportunities ... for collaborations with our peer AAU and flagship universities in education, research, and innovation will boost the University of Maryland's ascendancy in academic excellence."

Oh really?  Let's look at the evidence, shall we?  The ACC has 12 schools including UMD, and has just added 3 more.  Using the U.S. News rankings of national universities, we can calculate that the average ACC school is ranked 48th in the country.  The average Big Ten school is ranked 58th.  (UMD is tied for 58th nationally.)  So although the Big Ten isn't bad, a move to the Big Ten from the ACC is clearly a move down academically.

Dr. Loh is a smart man, and I doubt he truly believes that joining the Big Ten will help Maryland academically.  But he does claim it will help the athletes.  He claimed that:

 "We will have the capability to support better our student-athletes -- in the classroom and on the field -- and compete successfully at the highest levels."

Never mind that the Big Ten schools are, on average, much further away from Maryland than the ACC schools, which will require more travel from the athletes. But travel is educational, right?  

Obviously this is all about the money.  USA Today's headline got it just right: "Maryland leaves ACC for more money."

Here's a question for Dr. Loh: since Maryland will make more money in the Big Ten, will you pay your athletes higher salaries?  Oh right, these are "student-athletes": they mustn't get paid!  Never mind that their coaches make the highest salaries in the university. 

Why does no one seem surprised that a university president, a highly educated scholar with both a Ph.D. and a law degree, is spending so much time on football?  Why is a university spending any time at all running a big-time sports entertainment system?  As I wrote last year:

The football-industrial complex has too much power over our universities. Nothing else can explain how we spend so much money and time on football, which contributes almost nothing to students' education, while academic departments are cutting faculty and staff. The culture of football worship has gotten so out of control that I think the only solution is to get rid of it entirely.

It's not just UMD.  For instance, just last spring the University of Florida proposed to eliminate its Computer Science department to save $1.4 million, while simultaneously increasing its athletic budget by $2 million.  After my article about this plan went viral, UF's president reversed that decision.

Stated simply, football has corrupted America's universities.  Top administrators have completely lost sight of their academic mission, and instead seem to believe that their primary job is to provide sports entertainment for the TV-watching public.  There is only one way to fix this: get rid of football.

But wait!  Football fans don't have to lose their beloved teams.  I have a better proposal.  Each university can spin off its football program as a for-profit, separate enterprise.  The team can pay license fees for the use of the university's name and pay to rent the stadium.  Then it can pay its coaches whatever it wants; after all, they won't be university employees.  More important, these minor-league professional teams (which is what they already are) will have to pay their athletes.  We should get rid of the current system, where the athletes are basically indentured servants. (For more on this problem, see Taylor Branch's remarkable piece, "The Shame of College Sports", which sportswriter Frank DeFord called "the most important article ever written about college sports".)  

Let's remind university presidents, and boards of regents, and everyone else involved in running a university that their mission is to provide education, research, and training for their students and the world. They should get out of the business of providing television entertainment.  And they should most certainly put an end to the practice of profiting off the labor of unpaid student athletes while neglecting their education.

How to predict an election? Ask the math geeks.

Mark Newman's rendering of the 2012 U.S. election,
 weighted by population

It's time for a bit of gloating.  No, not for Democrats over Republicans, though I'm sure that's going on.  It's time for the math geeks to throw a bit of scorn at those insufferable, over-confident frat boys who call themselves political prognosticators, and who spent most of the past two years telling us that they knew how the election would turn out.  They bloviated endlessly on talk shows, explaining why their favored candidate would win, and how he would do it.  

Politicos behave just like promoters of quack treatments when things go wrong: they always have a ready answer, and somehow their "theories" can never be proven wrong.  It seems that the only thing these guys are really expert at is getting themselves onto talk shows. Now that the election is over, let's hope that happens a bit less often.

Instead, pay attention to the math geeks.  The statisticians and analysts who build mathematical models based on multiple polls and other data absolutely nailed this election.  Nailed it!  Nate Silver at FiveThirtyEight blog predicted the winner of the presidential election in all 50 states.  So did Sam Wang , a biophysics professor at Princeton, over at the Princeton Election Consortium blog.  And so did Simon Jackman, a political science professor at Stanford who writes for HuffPo.  Nate Silver first drew everyone's attention in the 2008 election, when he correctly predicted 49 out of 50 states.  Last week's success shows that this is not an anomaly, although it has the mathematically challenged pundits in a tizzy.

Hopkins statistics professor Jeff Leek wrote a nice explanation of how these models work over at Simply Statistics, so I won't explain it here.  Suffice it to say that mathematical models don't work by chattering with their buddies at political rallies.

Mathematics delivered the goods.  And make no mistake, this is the way of the future.

That hasn't stopped the punditocracy yet.   On election night, Republican hatchet man Karl Rove was sputtering on Fox News that Romney could still win, after Fox News itself - which is little more than a media arm of the Republican party -called Ohio and the election for Obama.  Rove, who predicted that Romney would win with 285 electoral voites, also orchestrated the spending of over $127 million on Romney, not to mention his spending on 12 Senate candidates, 10 of whom lost.  Has he admitted he did anything wrong?  Nope.

Rove wasn't the only one wrong.  As Techcrunch pointed out, 

"every single major pundit was wrong - some comically wrong."  

The Atlantic created a detailed score sheet listing all the pundits and their predictions of the overall winner, the electoral college total, and the winner in all the swing states.  And indeed, even those who predicted correctly that Obama would win got most of the swing states wrong.

Here's what needs to happen.  The television networks need to realize that political expertise is meaningless when it comes to making statistical predictions.  Let's treat political forecasting just like weather forecasting, using models that are demonstrably accurate (such as Silver's).  Television stations can hire attractive political "forecasters" (because physical appearance matters on TV, like it or not) who will describe the latest forecasts just like today's weather forecasters do.  Now that I think of it, why not let the weather forecasters do both jobs?  We already have them in place at every local TV station in the country.  Think of all the money the networks will save.

But what about all that air time they need to fill with talking heads arguing about who will win elections?  Well, this makes about as much sense as having two self-proclaimed experts arguing about whether it's going to snow this weekend.  Maybe they can find real experts who will argue about issues rather than about who's ahead in the polls.

Ha ha, just kidding!  Who wants to hear about issues?  But if you must know how the race is going, ask the math geeks.

Why we want to believe chocolate makes us smarter

Eat chocolate, win Nobel Prize?

The New England Journal of Medicine published a study two weeks ago showing, amazingly, that eating chocolate might make you smarter.  To be precise, the author, Franz Messerli, was wondering if chocolate consumption might be correlated with the overall cognitive function of a population.  He couldn't find any data on national intelligence, so instead he used the total number of Nobel prize winners per capita.  The correlation between chocolate consumption and Nobels is remarkably strong, with a p-value less than 0.0001, meaning that the odds that this is due to chance are less than 1 in 10,000.

Ha ha! Dr. Messerli was just kidding.  Or was he?

The article itself reads like almost any science paper.  It includes a straight-faced presentation of the data and scholarly references suggesting that the brain-enhancing effect of chocolate might be due to flavanols, which may be "effective in slowing down or even reversing the reductions in cognitive performance that occur with aging."

In fact the entire article appears to be dead serious until the end, where Messerli makes the wry comment that

"The cumulative dose of chocolate that is needed to sufficiently increase the odds of being asked to travel to Stockholm [where the Nobels are awarded] is uncertain."

And then, in his disclosure of conflicts of interest, he reports "daily chocolate consumption, mostly but not exclusively in the form of Lindt's dark varieties."  Hmmm, this doesn't seem like a serious science paper after all.

Word of this article swept through the halls of academia the day after it was published.  I heard it being discussed among my colleagues, who were concerned that NEJM had published yet another example of misleading statistics.  It took a couple of days for us to realize that it was a joke - based on real data, but a joke nonetheless.

The media reported the story widely, and a few reporters figured out the ruse, but the parody was just too subtle for most.  Reuters wasn't fooled, as reported on their own site and on Fox News. They reached Messerli by phone, who confessed that

"the whole idea is absurd, although the data are legitimate and contain a few lessons about the fallibility of science."

The Associated Press reporters were slightly suspicious, opening with "take this with a grain of salt." But they went on to report it as straight news, and their story appeared on CBS News, the Huffington Post, and elsewhere.

Larry Husten, my fellow columnist at at Forbes, reported it as straight news with the headline "Chocolate and Nobel Prizes Linked in Study." Time magazine fell for it too.

Two medical websites, Medical News Today and WebMD, not only took the story seriously, but also bought into the explanation that the effect is caused by flavanols, which are found not just in cocoa, but also in red wine and green tea.  Sounds like an ideal diet to me.

Slate's Brian Palmer had an interesting angle. He reported the story as straight news, but then investigated why the Swiss eat so much chocolate.  (Answer: innovation in chocolate-making, and wealth.)

Why do we want to believe chocolate makes us smarter?  Well, obviously because we'd love for it to be true.  And as Messerli points out, there have been some serious studies linking flavonoids to better health and cognitive function.  But the notion that chocolate leads to Nobel prizes is a little too good to be true.  I'm reminded of the study that I wrote about back in April that claimed chocolate would help you lose weight - which was little more than wishful thinking masquerading as science.

Still, with Halloween just past, many parents are probably wondering how much to let their kids eat.  Those Nobel-champion Swiss consume about 11 kilograms per year, about 30 g (1 ounce) per day.  That's 3 of those little mini-chocolate bars.  And parents, maybe you should have a few too - just in case Messerli is right.

Multivitamins and cancer: a mixed bag

A major new study published this week in the Journal of the American Medical Association (JAMA)  came to the surprising conclusion that

"daily multivitamin supplementation modestly but significantly reduced the risk of total cancer."

The report included some caveats, such as the fact that all 14,641 participants were healthy male physicians.

But the result is still surprising, because other recent studies, some of them even larger, have concluded that vitamin supplements do not provide any significant health benefits.  On the contrary, some studies found that supplements could actually be harmful.  As I wrote last year, a very large study of 38,772 older women, who were followed for 25 years, showed that the risk of death INCREASED with long-term use of multivitamins, vitamin B6, folic acid, iron, magnesium, zinc, and copper.  That's death, not just cancer.  The authors of that study, Jaakko Mursu and colleagues, concluded that there is

"little justification for the general and widespread use of dietary supplements."

The new study, PHS II (Physicians' Health Study II) looked at overall death rates as well as cancer, and found that men on a daily multivitamin had fewer deaths, but too few to be statistically significant.

So we have a large study in men showing that multivitamins seem to reduce overall cancer, and maybe even death, but an even larger study in women showing the opposite effect.

A second study from last year, in 35,533 men, looked at vitamin E and selenium supplements. That study, also published in JAMA, found that risk of cancer INCREASED for men taking vitamin E, selenium, or both.

The media reports aren't helping to clarify things.  The NY Times proclaimed "Multivitamin use linked to lowered cancer risk, and the Wall St. Journal reported that "Multivitamin cuts cancer risk, large study finds."  Bloomberg News went right for the business angle, announcing that "Pfizer multivitamin reduces cancer 8% in men, study finds."

Compared to Bloomberg news, Pfizer's own website was remarkably restrained, saying only

"Centrum Silver was part of the recently published landmark study evaluating the long-term benefits of multivitamins."  

No claims about reducing the risk of cancer - surprisingly, the independent media made far stronger statements than Pfizer.  Not true of supplement manufacturer GNC, which was flashing a pop-up headline that "Taking a daily multivitamin could cut cancer risk", linking to a news article at the Boston Herald.

So what do we make of this new study?  Are multivitamins good for you after all?

The new JAMA study appears to be very well done.  It's a double-blind, placebo-controlled study in which half of the physicians received a daily multivitamin, Centrum Silver, and half received a placebo.  The participants didn't know if the pill they were taking was a vitamin or a sugar pill.  The authors report some minor conflicts of interest, but none of them work for or received major funding from Pfizer (PFE, the manufacturer of Centrum).  So how to explain the seeming contradiction with two larger studies published only a year ago?

To answer this question, we must look at the details of the study itself.  This study looked at 21 different types of cancer risk.  For most cancers - colon cancer, prostate cancer, lung cancer, pancreatic cancer, lymphoma, leukemia, melanoma, and others - multivitamins did not provide a benefit.  But when all the numbers were added up, the effect was just large enough to be "significant", at a level of p=0.04.  More on that in a moment.

Here are the raw numbers: among the 7,317 men who took a daily multivitamin, there were 1,290 cases of cancer over the 11-year study.  Among the 7,324 men who took a placebo pill, there were 1,379 cases.  That's about 1.2% more - far less than the 8% reported by Bloomberg News. The statistical analysis showed that this difference had a p-value of 0.04, a result the authors considered significant. When the authors looked only at men with no history of cancer, the effect was smaller, and not statistically significant.

One explanation of the new finding is that the effects were indeed due to chance. Let's look at that p-value of 0.04. In much of the scientific literature, any p-value below 0.05 is considered "significant," but this has been widely criticized, in part because it encourages binary "true, false" thinking that is not the way scientists actually think. Also, the "0.05 threshold actually represents evidence much weaker than the number "0.05" suggests. A back-of-the-envelope Bayesian calculation shows that if the cancer-preventing power of multivitamins was a 50:50 proposition before this study, then after this study there is still a 10-26% chance that the cancer prevention claim is wrong. If we thought that prior evidence made this effect less than 50:50, (say 25:75), then the study has roughly a 25-50% chance of being wrong.* Either way, I won't be stocking up on Centrum Silver anytime soon.

Looking at this small effect, and at the contradictory results from other studies, neurologist Steven Novella writes in his blog that

"About the only thing we can say with a high degree of confidence is that there is no large risk or benefit from taking a multivitamin. There may be a small benefit, no benefit, or even a small harm."

That's a good summary.  So should men take a multivitamin?  Well, it's your money, but if you don't have a vitamin deficiency, it's probably not worth it.  Should women?  The evidence still says no.

*Thanks to Stanford biostatistician Steven Goodman (formerly of Johns Hopkins University) for crunching some numbers to produce Bayes factors.