Thursday, June 11, 2009

How not to find cause of and cure for cancer

A friend brought to my attention (via a forwarded email that has been circulating for some time it seems) a certain Professor Jane Plant who claims in a book of hers that she's discovered a causal factor of breast cancer and that she was cured of her own affliction by eliminating milk products in her diet. The book may be old hat to some of you but I just got wind of it.

Just to be sure that this wasn't another urban legend, I turned to Amazon.com. Well, Jane Plant and her book Your Life in Your Hand (the US edition is entitled The No-Dairy Breast Cancer Prevention Program: How One Scientist's Discovery Helped Her Defeat Her Cancer) checks out. So much the worse for Plant as you'll see. Go read the widely available excerpt from her book (that particular website goes to show how governments are not necessarily keepers of the light, enlightenment that is).

Allow me to put cart before the horse and provide you my conclusion: Geologist and professor Jane Plant is incompetent. I say that because she's supposedly a scientist and yet she commits errors in thinking and analysis that would earn science undergrads a failing grade. How she could, in the same breath, remind us she's a scientist and write as a woowoo is jaw dropping.

Now for my arguments.

Plant tells us that it dawned upon her that in China practically no one drinks cow's milk and that dairy products including cheese are not part of the diet. She also says that statistics show that only 1 in 10,000 women in China die from breast cancer, while the figures for Western countries is around 1 in 10. (Let's at the moment just take for granted that she has her numbers right, although those would need to be checked too of course--I'm suspicious of the 1 in 10 stat). So Plant puts two and two together and comes up with the hypothesis that dairy product consumption might be a or the culprit.

Can we jump to the conclusion that milk is dangerous to women's health? Most certainly not. There's a truism in statistics and science: Correlation does not necessarily imply causation. Correlation is the phenomenon wherein two or more variables/events are associated with one another. For example, the temperature of the ground is correlated with the time of day--the closer it is to noontime the warmer the ground is. And of course this is because the sun heats the earth up. However, just because two variables are correlated does not mean one causes the other. The clock we used in recording the time of day obviously does not cause the ground to heat up. Yet another example. Over two decades ago researchers in Taiwan found that there is a strong correlation between the number of electrical appliances (including toasters) that a household owns and the frequency of use of birth control methods. Does this mean then that buying more appliances causes people to resort to contraceptives more often? Or does it mean that higher frequency of employing contraceptives makes Taiwanese buy more appliances? One of these would have to be our conclusion if correlation were equivalent to causation. The truth of the matter, however, is that the above variables are both correlated with yet other variables, namely, income and educational attainment. And it is these two latter factors that cause the increase in both number of appliances owned and contraceptive use. Income and education are both correlated with the former two variables. They also are causal factors.

In summary, if X is correlated with Y then either X causes Y, or Y causes X, or neither X nor Y is a cause of the other. On the other hand, if Q is the known cause of P, then Q and P will by necessity be correlated with one another. So while correlation does not necessarily imply causation, causation necessarily implies correlation.

In discussing Plant's hypothesis, another friend reminded me of how the Chinese consume a lot of soybean in its various forms--tofu, soybean milk, soy sauce, salted soy beans, etc. That in itself would correlate significantly with breast cancer mortality since Westerners consume less soybeans than Orientals. Just as with dairy products we could also say something like, It might be that the high consumption of soybean products guards against the occurrence of breast cancer. And these surely are not the only variables that correlate with breast cancer incidence and mortality. You could scour the world for various factors and find correlations, both positive and negative.

Plant goes on to tell us that based on this correlation and hypothesis of hers, she stopped taking any product that contained milk. She narrates what happened soon thereafter:
About two weeks after my second chemotherapy session and one week after giving up dairy produce, the lump in my neck started to itch. Then it began to soften and to reduce in size. The line on the graph, which had shown no change, was now pointing downwards as the tumour got smaller and smaller.
She goes on to conclude that based on her experience she was right in identifying milk as the cause.
It was difficult for me, as it may be for you, to accept that a substance as ‘natural’ as milk might have such ominous health implications. But I an i living proof that it works....
Well, unfortunately for Plant, her reasoning is flawed. She commits the post hoc ergo propter hoc fallacy (after this, therefore, because of this). This is a causal attribution error whereby just because event B comes after A, we conclude that A caused B. Thus, just because the sun rose after the rooster crows obviously does not imply that the chicken made the sun rise. But this is precisely what Plant is saying. She tells us that she stopped taking any dairy product after which she noticed that her lump started waning until it totally disappeared. She then attributes this to her diet change. This is a textbook case of causal attribution error.

But note how she herself tells us that she was simultaneously undergoing chemotherapy, a treatment modality that is known to work against cancer. Why does she not attribute the remission to chemo? So what actually caused her lump to up and disappear? Well, we don't know for sure. It may have been the chemo, the diet change, both of these, spontaneous remission, or something else. To jump to the conclusion that it was diet change is to commit the post hoc fallacy.

Furthermore, Plant has the gall to jump to a conclusion based on her own personal experience. One anecdote is not evidence. And even if a thousand other women shared a similar story, it would still not be evidence. Thus, the aphorism goes: The plural of "anecdote" is not data, it's "anecdotes." And even if this had been a clinical trial, it is impossible for it to be a randomized controlled study for the simple reason we'd need to have at the very least two participants in the study--with one serving as the control. A clinical study with a sample size of two is in itself laughable--the margins of error would be so huge as to make its results practically useless. Hence, a sample size of one is just absurd.

Linda Bily, a reviewer on Amazon.com of Plant's book, likewise apprehends the lack of critical thinking that Plant manifests and has this to say:
The premise that since Oriental women don't consume a lot of dairy products and have less incidence of breast cancer is plausible, but unproven. I shudder to think of the thousands of women who will change their diets based on this book. I am most concerned that the high intake of estrogens and phytoestrogens, especially in the soy products recommended, could be detrimental to some women. There is still controversy in the medical community about the use of soy. If you read this book as an interesting scientific, but unproven, premise, you will be fine. If you take this book to heart, without consulting your medical specialist, you could be opening a can of worms. Dr. Plant is a respected scientist in her field. As a breast cancer survivor and advocate, I question some of her findings. The studies she cites to validate her ideas are older, some of obscure practice and are not widely confirmed. I also take issue with her description of her own breast cancer diagnosis. It returned 5 times according to the author and yet she states that it was an early stage at diagnosis. The tumor on her neck disappeared during chemo and she credits only her non-dairy diet for this shrinkage. She says that it spread to her lymphatic system, but her lymph nodes were clear. The book is interesting reading, but while I do not doubt her personal beliefs or her expertise as an earth-based scientist, I do hesitate to recommend this book to anyone. I am afraid that too many women, looking for a quick fix, will adapt her lifestyle without question. There still is no known cause or cure for breast cancer. Feel free to search alternative options and methods, but please, discuss any changes in your treatment, diet or life with your medical team and make an informed decision.

So, is Jane Plant's hypothesis that dairy products are a casual factor in breast cancer wrong? Certainly not. Let me repeat that in case you think that's a typo. It may be that regular consumption of dairy products are (partly) responsible for breast cancer. My critique above does not imply that Plant's hypothesis is totally off the mark. What is utterly awry are the methods/reasoning by which she reaches her conclusion, which means it is nowhere close to being conclusive. Keep in mind that an argument may have false premises but true conclusions. When the argument contains various fallacies then the conclusion cannot be known to be true. However, if the argument is sound (i.e, the premises are known to be true and the argument contains no fallacies) then the conclusion must by necessity be true. Because Plant does not follow scientific protocol (ie., objective, unbiased methods of testing hypotheses) we cannot have any confidence in her conclusion.

As a scientist, what Plant could have done is applied for a grant and performed randomized, double-blind, controlled clinical trials (RCT) employing at least several dozens of participants. Barring this (for ethical or whatever reason), she could've performed an epidemiological study (just as was done with tobacco use and lung cancer decades ago), although such studies hardly provide the degree of certitude of RCTs. (But since she has no degree nor expertise in medicine I doubt she would've been awarded research money in the first place; thus she should've left testing of this hypothesis to the experts).

It is said that when a layperson makes a mistake in matters of, say, rocket science then that mistake is out of ignorance. But when a rocket scientist commits an error involving rocket science, that's stupidity. Prof. Jane Plant claims to be a scientist. But she made elementary mistakes about hypothesis testing and induction. Now that's utter stupidity.

As we've seen above Plant says of her cancer treatment: "I am living proof that it works." No, Prof. Plant. You're living proof that you failed to learn the essentials of Scientific Method 101. For shame!

18 comments:

Patty said...

Hear, hear! Great post. I just got the selfsame e-mail about Jane Plant's laughable assertion that dairy consumption causes breast cancer and how she cured herself it. It boggles the mind that in this day and age that a seemingly educated* person can still make such claims. I wasn't surprised then to learn that Plant is a geologist and not a medical scientist by any stretch of the imagination. She should stick to rock cancers, not human ones.

* I have to add that unfortunately, it was my "educated" chemist mother who sent the e-mail to me and is now eliminating dairy products from her diet. I think it is high time that critical thinking be taught in all universities!

Anita said...

I don't understand why someone can be against Jane's argument. It has been accused of not being scientifically proven. Well, the true science is based on experiments and this is the result of her own 'experiment.'

Jo said...

Actually her last chemo as per the book was not working and they had given her months if not weeks to live. If she was not cured I think her breast cancer being that it had already metastasized would have almost certainly come back by now and it has not. Her cancer was considered 'early stage' before it metastasized. Also lymph nodes that are 'clear' in the axillar area does not rule out that the cancer has spread through the lymphatic system to other parts of the body. This is certainly a possibility although generally negative nodes mean cancer has not yet spread. She does deal with the Chinese consumption of soy actually but comes to the conclusion that as so many women in the Western world are now regular consumers' of soy milk and other products but still get breast cancer that this was not the reason why Chinese women have such incredibly low rates of breast cancer.
I for one had breast cancer seven years ago and feel extremely lucky to have found the Jane Plants book. It gave me hope and I do genuinely believe her theories. And I am a highly educated person in the medical profession. She does not just attribute her 'cure' to giving up dairy but to other causative effects also such as xenostrogens, chemicals in our cosmetic and toiletry care amongst others and she changed her whole life not just the stopping dairy.
Milk natural? Yes, natural for baby cows who have several stomachs to digest it and who grow at an astonishing rate compared to its human counterpart. She also made the connection with consumption of beef which is in fact quite often a dairy cow who has had its wretched life being in calf and lactating an abnormally large amount for the dairy industry. Jane Plant said meat from dairy cows is actually more harmful than dairy. Guess what? recently all over the papers was the news that red meat has definitely been found to have a correlation to reproductive cancers such as breast, ovary and prostrate. My oncologist agreed with the findings.
Plus the person in this forum who says how she dreads all the phytoestrogens in soy will make breast cancer worse has no idea what she is talking about. phytoestrogens work in competition to xenoestrogens such as dairy and other hormone disrupters in perfumes and cosmetics. They work in a similar way to the drug Tamoxifen which is given to women with Estrogen positive tumors.
I am really convened that giving up dairy has kept me cancer free. At the time of my diagnosis aged 43 I was having soya milk but lots of dairy and beef as I was on teh Atkins diet. Before that I never used to touch dairy but during Atkins I would consume loads of cream and cheese and red meat for the first time in my life. I don't think it was a coincidence that my breast cancer was diagnosed at that time.
Also I did the Jane Plants juices during chemo to stop my hair from falling. Oncologist said I would definitely loose my lovely long hair with the kind of chemo I was having..well guess what again? Not one hair! they were astounded!.

Any chance that the Dairy board is involved in these malicious accusations towards Jane Plant? ummm...

Anonymous said...

Well my aunt is from China, and she had breast cancer, which requried a mastectomy. So the statement about Chinese women not getting cancer is false.

adriennetse said...

Thank you for your post! It is comforting to be reminded that there are other people out there who are capable of critical thought. I often feel as if I am fighting a losing battle trying to explain why such email forwards are not worth the space they occupy in our virtual mailboxes.

I am frustrated that there is so much easily accessible and highly misleading information online in an age that is supposedly as enlightened as our own. It is yet more infuriating to come across such nonsense being disseminated by people who claim to have a solid grasp of scientific reasoning.

As a person with a background in both research and education, I feel strongly that, as a society, we need to promote scientific literacy so that the average individual is capable of distinguishing between good and bad science. Particularly in light of the huge amount of information we are bombarded with daily. Your words are therefore much needed. We really should not have to feel like a minority or be made out to be unreasonably skeptical when we point out flaws in poorly considered arguments.

Thank you again for your thorough and well-written post. Your blog is new to me and I will be following it with considerable interest. I have a feeling I will also be sending links to it whenever I get forwards from far too many people I know...

Anonymous said...

sorry to but in here, but it looks like you have not actually read her book, in her book she clearly states that Dairy produce can promote Cancer, which..and i do urge you is peer proven and documented, again check her book, (she compares the risk of Dairy and Breast Cancer to be the same as Smoking and Lung Cancer)..and in time you will see this become a 'fact'. Although skeptics like the people on here always like to 'shoot down in flames' anything they don't or won't understand...Doctor's in the 1950's smoked for Crying out loud!...and before then only Mad people and Witches were burned at the stake for suggesting the world could be round...oh please don't get me started, there's already masses of research going into new Drugs derived from plants, Curcumin to name but one, oh and by the way she does not claim to cure Cancers, her diet and advice is based on Hormonal Cancers and nowhere does she ever suggest not trying conventional treatment....and there's loads of evidence linking growth factors to Cancer, do a little research before you 'sound off' at the safety of your own computer

Anonymous said...

Edwardson, you have gone to a massive effort to attack jane, are you jealoss of her or something?..mmmm no smoke without fire eh, ? you sound a little 'corporate' to me, come over to the happier side of the argument, its sexier and we have more fun you old stick in the mud you, you would have been one of those Doctors telling people that Smoking was ok in the 1950s

Anonymous said...

I agree with anonymous... Bet the critical reader works for the milk marketing board...and I bet she hasn't got cancer... Lucky her, but if she had she would lay awake for hours praying that the strange pains are not secondaries, and praying that your life can go on not wanting to leave the party yet :-)... I am a nurse and midwife, and what we have to do is work from research based evidence, and Jane
's book is full of it..... Thank you Jane, you give me hope when all else is against me xxx

Barbara - bluehills9 said...

I would not be too quick to disregard Jane Plant's book. Today in our Western countries dairy products are implicated in a number of health issues. Cancer, diabetes and osteo-porosis being the commonest ones.
But, just think; only mid-20th century was milk generally pasteurised and homogenised. Before that it was all raw. Raw milk and butter were used in the early 20th century to cure diabetes and cancer. Google it.
So many people through European and high altitude Asian countries consumed big amounts of dairy - milk, yoghurt, cheese, savoury and sweet dishes, for healthy people and ones recovering from illness. Heating milk destroys the essential anti-cancer fatty acids and enzymes, leaving only dead, heat contaminated substances with very little nourishing nutrients. Where they still consume raw milk, butter, cream, cheese and yoghurt the people do not have a high cancer rate of any kind.
The next important things as also mentioned by 'Jo' are the other changes from chemical laden everyday things, fruit and veggie juices and a competely wholesome diet of raw food, as often as possible or lightly steamed and lastly good quality vitamins, anti-oxidant and mineral capsules or powders.
I have uterine cancer and the above approach works - not one thing or another - all together synergistically. The hardest part to employ strictly was the change of food with 'no exceptions' but now it is resolving. So, if anyone reading this has cancer, drop the dairy products first, then get started on the other changes. You will not die, but your health will start improving and as the changes come it strengthens you mentally and physically to feel good about yourself and continue on. You must though continue it for some months after all traces and tests of it are positive. Good luck. Barbara.

Anonymous said...

To all those who are cancer sufferers, I say, "Try it. You have nothing to lose"! If it works, the better for you. The science behind it is immaterial.

Paul Hardy said...

Barbara -- if you read properly you will see you'll see the author doesn't dismiss the possibility of the outcome, but questions Plant's scientific rigour which makes her conclusions unreliable.

I am amused by the 7th commenter who accuses the author of attacking Jane (when he is attacking her slapdash methods) and then makes up an ad hominem suspicion about commercial sponsorship -- shame on you!
And Edwardson -- you are right the 1 in 1000/ 1 in 10 comparison is wrong; Plant compared the _incidence_ in China with the _lifetime risk_ in the UK

Innocent Bystander said...

The interesting thing has so far gone unmentioned is that Chinese women, when transplanted (no pun etc) to a western society and diet, become subject to the 1:10 risk. By the way, it's now said to be 1:8!

Roger Fenton said...

I read her book last week while on holiday – I didn’t know whether to laugh or cry. Eventually I just got angry and threw it in the bin, where it belongs. She claims to be a scientist – I can find no evidence of this, by the way – but this might just be the most unscientific work I’ve read in my life – and I’ve read a great deal on related topics.

Yes, there is some peer-reviewed work in the book – and a vast amount of hokum from all sorts of sources, blended seamlessly in with the “real” stuff. She frequently uses phrases like “I honestly believe” – sorry dear, scientists do not “honestly believe” when they’re being scientists. They suspect, then they test, using the kind of rigorous peer-reviewed methodology which you claim to revere, yet ignore when it suits you, which is very frequently.

No, I am not involved with the dairy industry, never have been, etc. I am an IT Manager. And actually, the really sad thing is that there is some merit in the book – I think she just might be onto something with her dairy/cancer hypothesis. I could use some of her phraseology at this point, and say that “I really believe” dairy foods probably aren’t very good for us, and “don’t you see how much sense it makes”.

But one thing is for sure – you should not take any of her ramblings as evidence. Of anything.


Anonymous said...

I think Edwardson is too tied up in academic logical argument in trying to discredit Jane Plant. His professorial logic puts Plato and Aristotle in the shade - and doesn't impress me. I've read her book. Her story and conclusions make sense. She is still alive and well and living proof of her theories. Of course, if her theories were widely accepted, there would be economic uproar as the dairy industry went down the drain.

Anonymous said...

I am astounded at the shallow nature of this review. Janet Plant deserves proper consideration, and if the reviewer had read more of her books and the detail of her testimony, they would have not been able to proffer superficial arguments in this manner. Janet is a significant scientific figure respected by governments and global bodies, and garners respect for her pioneering work in many quarters. To accuse her of taking simplistic statistics and jumping to naive conclusions is in itself an act of naivety and vain stupidity. I was diagnosed with aggressive cancer and am now healthy than ever influenced by her approach and diet. I am also intrigued by other medical researchers whose current opinions largely merge with Janet's,on the subject of diet, and yet coming from a different angle.

Anonymous said...

I've arrived at your post after reading a review of Plant's book in an internet newspaper. The reporter accepted Plant's unsound opinion dearly to her heart. Only, who wouldn't wish cancer diagnosis and cure was so EASY? If it is was so simple and straightforward, all those doctors and epidemiologists would be morons... Thank you for writing a worthy summary that everybody should read before following the advice that lacks proper justification. I am a theoretical physicist with no connection whatsoever to the dairy or farming industry.

Beefwalker said...

(1) You can't say Oriental - that's a pejorative term. Sorry. I'm sure it's an honest mistake, but really, you may as well have said 'yellow chinky person'.

Beefwalker said...

(2) Westerners in general consume FAR more soy products than our Asian counterparts. Soy is 'traditionally' consumed in Asia in very small quantities, and traditionally (i.e. The only time it's not unhealthy) it's fermented.