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edge

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Reply with quote  #1 

I'll be a meanie again:


Much in the news lately is the Swedish study  by Jingmei Li and colleagues which claims that coffee consumption reduces the risk of estrogen-receptor negative breast cancer.  In fact no such thing is true.

 

Flaws in the Ointment

This was a case control trial using self-reporting methodology, asking subjects to remember their coffee drinking habits and levels of consumption many years before, and claimed to find that subjects who claimed to remember that they drank more than 5 cups of coffee a day were 20 per cent less likely to have breast cancer, compared to those who didn’t drink any.  Besides the limitation of recall bias, another limitation was that receptor status was unavailable for approximately 35%  of the population

65.4% of the Swedish population, and still further limiting is that fact that the study failed to differentiated different kinds of coffee - caffeinated, decaf, instant and brewed, etc.


Self-Contradictory Study

But  that coffee consumption reduces breast cancer risk is in fact is not the conclusion drawn by the study, despite being misquoted as such in innumerable medical reporting media.

 

Why?  Because the apparent 20% difference in breast cancer incidence between coffee-drinkers and coffee-abstainers may have been confounded by differences in (1) level of physical exercise , (2) alcohol consumption, (3) subject's age, among many others.  And - no surprise to this researcher - once the authors adjusted the statistics for these other cofounders/co-factors, the putative protective effect of coffee was no longer statistically significant.

 

But more controversially, however, the authors claim to find even after such adjustment, that for subjects who were ER-negative and drank more than 5 cups a day, a 57% lower likelihood of breast cancer remained compared to those who were abstainers, and the effect was statistically significant.  But this was a subgroup analysis, and like all subgroup analyses, the claimed association may simply have been a fluke, and indeed, this is confirmed oddly enough by the  authors themselves.  How? The authors of this Swedish study attempted to validate their results in the independent population based case-control MARIE study which was conducted in Germany by the  same investigators, and the MARIE study in fact found no statistically significant protective effect regardless of subgroup, including ER-negative populations.  Thus this much larger validation study failed to confirm the findings of the smaller original Swedish study, hence the validation was disconfirming. 

 

What the Evidence Says

And if we look at the larger  picture, outside of this methodologically flawed and cross-disconfirmed study, we find contradictory data. Thus, the prospective study (2009) of 61,433 breast cancer patients conducted by  Susunna Larsson and colleagues at the Karolinska Institute failed to support any role of coffee consumption in the development of breast cancer.  In addition, two meta-analyses contradict the Li study: a meta-analysis (2009) of 9 cohort and 9 case-control studies conducted by Naping Tang and colleagues in Shanghai suggested a possible influence of high coffee consumption or an increased coffee consumption on the risk of breast cancer, and similarly, Lenoe Arab at UCLA reviewed (2010) the findings of meta-analyses and individual studies on site-specific human cancers among coffee consumers, finding no association with breast cancer.

 

And Deborah Boggs at Boston University and colleagues examined (2010) prospectively coffee intake in relation to risk of breast cancer in the Black Women’s Health Study (BWHS), finding that neither coffee nor caffeine was significantly associated with breast cancer risk according to either menopausal status or hormone receptor status. While Nirmala Bhoo Pathy in The Netherlands and colleagues investigated (2010) the association of coffee and tea consumption with the risk of breast cancer among women in EPIC-NL cohort, a population-based prospective cohort in Netherlands with 27,323 participants, finding that coffee consumption was not related to the risk of breast cancer in women.

 

Clinical Lessons

In sum therefore, from a critical appraisal of the Li Swedish study and the MARIE German study, along with a review of  the aggregate evidence to date fails to find any convincing data to suggest a beneficial effect of coffee consumption on breast cancer risk, regardless of  menopausal status and regardless also of ER status.  And despite taste, higher levels of  coffee are known to raise serum cholesterol, adverse for  coronary health (myocardial and cerebral infarction), aggravate insomnia, impose cardiovascular complications, and caffeine's effects on adenosine receptors and subsequent withdrawal is accompanied by muscle fatigue and allied problems in coffee-habituated users, can impact negatively on postmenopausal vasomotor symptoms, among many other health-adverse events (including via drug interaction, interfering with oral contraceptives). 

 

I am note, not addressing the social aspects of coffee drinking, much as I don't assess the social aspects of alcohol consumption: my focus is necessarily on health effects, and - as here - on the  methodological validity of claims for a health-beneficial effect of coffee on breast cancer, and these claims are, on balance of the best-evidenced and critically appraised data to date, invalid and unsupported by robust data.



Constantine Kaniklidis

Breast Cancer Watch

edge@evidencewatch.com

Calico

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Reply with quote  #2 
Don't consume with broccoli  

But......what about anti-oxidants?? (grasping for one last good reason)

I hypnotized myself....my body actually thrives on coffee and the hypnosis negates all reasons mentioned below except the adenosine thingy....I don't know what that is  





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nosurrender

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Reply with quote  #3 
A little brocolli won't hurt us, will it??
Coffee - I remember a couple of years ago a study that said it CAUSES cancer.

I say- Drink Gin!


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MicheleS

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Reply with quote  #4 
oh for the love of G-D... first you tell me to stop drinking wine, now no coffee either??  what's next, my xanax?

I'm off to go sulk and gnaw on my apricot seeds.

Calico

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Reply with quote  #5 
Michele,
Xanax and Coffee??  

Had to laugh at Gina's expression regarding the seeds, "must have teeth strenght"



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edge

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Reply with quote  #6 
Michele, Calico, Gina:

Best to partially pre-gurgitate the kernels. 

This lovely machine can be used to crush the apricot kernels (fits snugly in most suburban malls or nuclear dump sites):



$850,000.
Powered by a broccoli-wine biodegradable energy source (not supplied).

Constantine 

Calico

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Reply with quote  #7 
  

What a lovely 'little' device......Let me think about it....the wine and broccoli might be just to valuable for operational costs........but the thought of it is intriguing  

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edge

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Reply with quote  #8 

Calico:

 

The Apricot Crush

Yes, beautiful isn't it!  And instead of broccoli-wine fuel, it does also run alternatively on 2,200 "AA" batteries (not included) should one feel so inclined (as you can see, this  is not your ordinary throwaway apricot kernel cruncher; and if you order before midnight . . . ).

 

Coffee Madness, Reclarified

On an unrelated matter, shifting from apricot kernels to coffee beans:

 

Just to be clear, I'm not enjoining against modest coffee consumption, and in fact I didn't address the issue of consumption levels at all, but rather focused solely in the above critical appraisal on the demonstration that the widely acclaimed Li Swedish study does not in fact demonstrate (1) any benefit of coffee in breast cancer in general, and (2) nor in ER-negative breast cancer where it was claimed that coffee, uniquely in that subgroup, decreased breast cancer risk.  The study's methodological flaws that I documented disallow these conclusions, and furthermore the authors themselves, quietly (not to draw attention) provide a direct refutation of the latter claim: they - perhaps unwisely in retrospect -conducted  a validation analysis using a larger German trial, MARIE, which they themselves had previously  conducted, and the results of MARIE showed that their conclusions (in the Swedish study) were in fact in error, and there was absolutely no benefit of coffee consumption on breast cancer risk, regardless of receptor type (it is not often that a study provides its very own disconfirmation!).

 

I did however note, that independent of the bankruptcy of this study missed in all the hoopla, and its unsupported claims, coffee is not without some non-trivial concerns, especially its adverse effects on lipids  (and coffee is notorious as one of the most adverse agents in reflux disorders (GERD)), but it  is unlikely that these effects are clinically relevant under modest sporadic and/or consumption (3 to 4 cups weekly as low consumption, but generally modest at less than one cup daily) in most cases. 

 

The one caution is the recent (2010) results from Lena Nilsson and colleagues at Umeå University (Sweden)  who found that total coffee, including both filtered and boiled, was associated with an increased risk of premenopausal, but not postmenopausal, breast cancer.  For complex reasons, I am not wholly convinced of the robustness of these findings, largely because coffee consumption in Sweden as the authors admit, in contrast to that in the USA, is high, and this high coffee consumption may have allowed the authors, as they acknowledge, to detect associations not present in populations with lower intake levels.  Be that as it may, we need future, far more robust and mature data to settle  this question dispositively, but at the moment the aggregate data does not at least support any beneficial effect of coffee on breast cancer risk.  So, assuming no contraindicative factors (especially reflux disorder and dyslipidemia), drink in moderation as I sketched above, for taste, but not for any expectation of benefit to breast cancer risk.

 

Gunning for the Messenger

Next week I will be offering decisive evidence that food - except for olive oil, Greek-Mediterranean, and Indian - is not good for your health . . . (I've taken to wearing a disguise when out in public).



Constantine Kaniklidis

Breast Cancer Watch

edge@evidencewatch.com

Calico

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Reply with quote  #9 
Edgy,
about that food thingy next month......I'd start counting now to see how many of the 9 lives you have left  


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Limner

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Reply with quote  #10 
A cup of organic Columbian or Cuban makes me feel like I can Do IT!   It may not be science, but it is good medicine.  I know, this is not a picture of coffee, but it sure looks good, ?si?  Marie de Carlotta
 

Attached Images
Name: flan.jpg, Views: 235, Size: 114.84 KB



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Calico

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Reply with quote  #11 
Awwww..... Mary....I would love to share that with you but would not have a problem ordering one for each of us!!! And yes, a good cup of coffee with it is a MUST

Just so to satisfy Edgy, yes...coffee is a stimulant....I was drugged with Versed today (Colonoscopy), had a few cups at noon and I am spinning....no nap....probably not before 2.00 am lol....

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Limner

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Pathfinder Angel
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Reply with quote  #12 

Mmmm Versed  - better than flan.  I wish they would give me versed for every treatment and procedure. 


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Dear friend, theory is all grey, and the golden tree of life is green. - Goethe
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