The BCA “Plethora of evidence”: The Fallon Paper
Jun 28
Posted by: colinhockings
Green Tea (Wikimedia Commons)

A BBC article on a study (PubMed) by a group, led by Dr. James Cardelli at the Louisiana State University Health Sciences Center, reports that green tea extracts slow the progression of prostate cancer. It has also been reported on by Reuters and (briefly) in the Daily Mail, as well as various blogs such as Attorney-at-Law and BloggingStocks and a health information network that seems to focus on alternative medicine called HealthNews.

The study itself is not perfect. They took 26 patients with stage I, II or II prostate cancer who were scheduled for radical prostatectomy (removing the prostate) and gave them a high dose of polyphenon (a green tea extract marketed by Polyphenon Pharma) until the day before the operation. As the most important outcome (survival) is hard to measure, especially in a single-armed (i.e. one group) trial like this, they measured serum biomarkers (signalling molecules in the serum) that seem to correlate with prostate cancer progression: HGF, VEGF, PSA and the IGF-1/IGFBP-3 ratio before taking the pills and before surgery. They mention the small sample size and lack of a control group but don’t, to my mind, make these limitations clear when they discuss their results. There’s nothing wrong with it, as a purely preliminary trial, but it is very poor evidence. The American Association for Cancer Research (AACR, the body that published the study) press-release has a very important statement about this which was left out of all the reports I’ve seen on this study:

William G. Nelson, V., M.D., Ph.D., professor of oncology, urology and pharmacology at the Johns Hopkins Kimmel Cancer Center, believes the reduced serum biomarkers of prostate cancer may be attributable to some sort of benefit relating to green tea components.

“Unfortunately, this trial was not a randomized trial, which would have been needed to be more sure that the observed changes were truly attributable to the green tea components and not to some other lifestyle change (better diet, taking vitamins, etc.) men undertook in preparation for surgery,” added Nelson, who is also a senior editor for Cancer Prevention Research. However, “this trial is provocative enough to consider a more substantial randomized trial.”

This is the most sensible thing I’ve read about the study, clearly summing up the fact that while there may be an effect, this trial doesn’t show it at all convincingly. It also occurs to me that the samples from before and after treatment were all run on the same ELISA, i.e. the sample from before the treatment was stored at -80°C for between 12 and 214 days longer than the second sample. This may not be a problem, but I didn’t notice any acknowledgement that the researchers considered it. This is why we need control groups! With more participants and a control group you could say ‘well…they might have changed their lifestyles and some parts of the serum may be destroyed by cold and Mercury may have entered Vesuvius, but the treatment group still shows a benefit”. Clearly, such a preliminary trial is not worthy for publishing on its own, so the researchers also tested the safety of such high doses by measuring the liver function (verdict: safe) of the 26 patients and an in vitro study of fibroblast cells treated with EGCG (epigallocatechin gallate, the most common catechin in polyphenon).

Regarding the BBC article itself, I noticed three errors that are quite revealing:

  1. It claims that polyphenon is a compound, which it is not. It is a complex extract from green tea leaves. This is the difference between buying a stack of bricks from the manufacturer and bulldozing a house – a compound is quite pure, while a complex mixture has many unknown components. While not necessarily important to the story, this mistake somewhat undermines my confidence in the scientific literacy of the author.
  2. The location of the study was given as Philadelphia – the address of each researcher (all in Louisiana) is given on the first page of the study. Where could this mistake have come from?
  3. The age range was given as 41-72, but the original paper seems to think it was 41-68.

The age-range of 41-72 also appeared on the Polyphenon Pharma blurb about the trial, published a few days later. The source of the discrepancy: the press-release from the AACR. The 41-72 age range was presumably a typo – if they knew the original article to be incorrect they would presumably correct it: it hasn’t even been published on paper yet.

Imagine my surprise when I re-read the first paragraph of the press-release:

PHILADELPHIA – According to results of a study published in Cancer Prevention Research, a journal of the American Association for Cancer Research, men with prostate cancer who consumed the active compounds in green tea demonstrated a significant reduction in serum markers predictive of prostate cancer progression.

So THIS is where the ‘Philadelphia-based researchers’ comes from – the press-release was written in Philadelphia. And, if we look closer, the first paragraph might also be the source of my other gripe: the ‘compound called Polyphenon E’. I may be wrong, but it seems to me that the author of the BBC article simply read the press release and regurgitated it, without ever taking the time to read the original paper. To be fair, though, I maintain my faith in the BBC News service to some degree because this lax effort was clearly not sufficient. The author got a statement from the head of the Prostate Cancer Charity – a modicum of journalistic investigation was performed, even if it began and ended with a call to the most relevant charity.

The Reuters article is a little better: it has the correct location and age range, and has some extra statements from the lead researcher, James Cardelli. There is nothing to indicate that the author read the original paper, but at least there were no glaring errors. In addition, it finishes with the observation that it ‘was a small trial and bigger studies would be needed to confirm the results’. The only thing I take exception to is the claim that the patients took the pills for ‘about a month’ – while the median duration was 34.5 days, the maximum was 214 days (although that was a special case – the next longest duration was 73 days) and the minimum was 12 days. I guess I may just be hard to please.

In conclusion: while I think it would be good to keep an eye on green tea as a potential supplement to cancer treatments in the future, this study is not the shining beacon that proves it. For a more balanced appraisal of the evidence then you’ll find in the media, I recommend searching PubMed for metastudies and literature reviews. As I expected, they mostly seem to say that while the pre-clinical (on cells in culture and in model organisms) research looks compelling, there haven’t been enough large, good-quality trials to show anything particularly significant in humans.

P.S. If you are a cancer patient and the sketchy evidence on the benefits of green tea make you decide to drink lots of it, first consider: a) green tea has caffeine – some studies of green tea showed a lot of side effects that were presumably due to the caffeine, and b) EGCG may interact with some cancer drugs, especially Velcade (bortezomib) so consult with your doctor. In general, it is a very bad idea to attempt to treat yourself with the preliminary results of trials of unlicenced treatments. They are unlicensed because their effectiveness, and more importantly their safety, isn’t known.

ResearchBlogging.org

McLarty, J., Bigelow, R., Smith, M., Elmajian, D., Ankem, M., & Cardelli, J. (2009). Tea Polyphenols Decrease Serum Levels of Prostate-Specific Antigen, Hepatocyte Growth Factor, and Vascular Endothelial Growth Factor in Prostate Cancer Patients and Inhibit Production of Hepatocyte Growth Factor and Vascular Endothelial Growth Factor In v Cancer Prevention Research DOI: 10.1158/1940-6207.CAPR-08-0167

Share and Enjoy:
  • Print
  • Digg
  • del.icio.us
  • Facebook
  • Google Bookmarks
  • email
  • Reddit
  • StumbleUpon
  • TwitThis

14 Responses to “Is it true that green tea ’slows prostate cancer’?”

  1. snails » Blog Archive » Potential New Target For Hypertension Treatment Discovered Says:

    [...] Is it true that green tea 'slows prostate cancer'? | Blue Genes … [...]

  2. green tea Says:

    Green tea has been consumed in China for more than 4000 years. I remember reading about green tea’s ability to fight cancer a number of years ago. I have it in Asian restaurants when I eat there but green tea is not easy to take to go. Tea is always grand on a rainy day I say.

  3. Tea Says:

    Research are going on green tea’s magical remedy against cancer and other health problems.

  4. Skeptics’ Circle #116 Says:

    [...] today. You may also find a link to my first ever post! A cup of skepticism about the promises of green tea for prostate cancer. Share and [...]

  5. Sexual Spells Says:

    What a very good viewpoint, although is just not help make every sence in any way discussing of which mather. Virtually any technique many thanks in addition to pondered try to reveal your current posting towards delicius nonetheless it looks like it’s an issue with all your blogging on earth do you you should recheck them. thank you once again.

  6. Cardiovascular Journals Says:

    Pretty nice post. I just stumbled upon your blog and wished to say that I have truly enjoyed surfing around your blog posts. In any case I will be subscribing to your feed and I hope you write again soon!

  7. Elder Care Coachella Says:

    It is in reality a great and helpful piece of info. I am happy that you simply shared this useful information with us. Please stay us up to date like this. Thanks for sharing.

  8. Brittani Goodstein Says:

    Whoah this weblog is fantastic i love studying your posts. Keep up the great paintings! You know, a lot of people are hunting round for this info, you could aid them greatly.

  9. Security Cages Says:

    Wow, incredible blog layout! How lengthy have you been blogging for? you made running a blog glance easy. The entire look of your site is excellent, as well as the content material!

  10. Paige Carlo Says:

    AHJ is looking for partners in the medicine niche. AmericanHealthJournal is a health care website which owns over three thousand of high quality medical videos. We are seeking website owners who are interested in featuring our content. We can offer content exchanges, link exchanges, and exposure to your site. Get in touch with us at our contact page on our website.

  11. heptomiindime Says:

    an burberry singapore sg burberry wallet vu burberry sale jk coach bags uk mz coaches for sale uk zs coach sales uk ug jersey nfl mexico ws nfl shop mexico lb tienda nfl mexico cu burberry wallet rf burberry thailand cp burberry bag ue gucci india qd gucci in india hx gucci india dj burberry online sz burberry spain aa burberry outlet online fw burberry outlet yx burberry bags ab burberry belts uz burberry bags sn burberry sale qb burberry outlet ra gucci france website zl gucci paris france tu gucci france website dx discount nfl football jerseys kr discount nfl jerseys rv discount nfl jerseys ho hermes thailand rl hermes shop in thailand tn shop hermes thailand di hermes handbags canada xt hermes scarves canada mf new hermes canada tq gucci australia sydney ii gucci australia uz gucci australia sydney sn burberry outlet online fi burberry bags lh burberry bags pa thailand coach en thailand coach ka coach thailand shop vi burberry online shop be burberry taschen mk burberry outlet online kg christian louboutin australia online mu christian louboutin shoes australia ko louboutin australia gg custom nfl jerseys qh custom nfl jersey ax nfl custom jerseys js uk burberry mq uk burberry zq burberry uk outlet na hermes birkin singapore xk hermes bag singapore am hermes singapore yr coach hong kong store hv coach hongkong cd coach hong kong limited oe cheap coach purses oq cheap coach bags pi coach purses cheap up nfl snapbacks australia gx nfl snapbacks australia tx nfl store australia sn gucci canada online ha gucci bags canada jv gucci canada online xc gucci uk hm gucci handbags uk ma gucci outlet uk fw nfl canada shop lb nfl shop canada ur nfl jerseys canada ot coach singapore lf coach singapore outlet rq singapore coach oa american football jerseys rz american football shirts ki american football jerseys jv coach usa ck coach outlet usa nz coach outlet usa er kids nfl jersey vg kids nfl jerseys cheap ap kids nfl jerseys qx louis vuitton sito ufficiale ge louis vuitton sito ufficiale borse ej borse louis vuitton sito ufficiale ky europe nfl shop va nfl store europe ox nfl store europe mv burberry sale pt burberry outlet yg burberry outlet of sac vuitton rv sac louis vuitton hz louis vuitton france dc coach clearance xh clearance coach purses jk coach clearance ed gucci singapore price list gx gucci singapore price list pp gucci singapore ix red sole shoes ul louboutin shoes sc christian louboutin outlet ds uk nfl shop wj official nfl shop uk vh nfl shop uk tu hermes australia kc hermes precisa australia le hermes australia pty ltd mv louis vuitton taschen xt louis vuitton neverfull as louis vuitton deutschland pk coach australia price nj australia coach ix australia coach pj borse louis vuitton outlet qb borse louis vuitton prezzi xk borse louis vuitton scontate tu burberry italia gp outlet burberry online pe outlet burberry pw burberry men am burberry store wr burberry store bu louboutin shoes canada jj christian louboutin shoes canada lw louboutin shoes canada

  12. 12465;& Says:

    Hello, i read your blog from time to time and i own a similar one and i was just wondering if
    you get a lot of spam remarks? If so how do you reduce it, any plugin or anything you can suggest?
    I get so much lately it’s driving me crazy so any support is very much appreciated.

  13. Sale Karen Millen DM094 Zig Zag Jersey Dress Says:

    Spending Doesn’t
    [url=http://www.komeon.com/sale-karen-millen-dm094-zig-zag-jersey-dress-p-743.html]Sale Karen Millen DM094 Zig Zag Jersey Dress[/url]
    Sale Karen Millen DM094 Zig Zag Jersey Dress

  14. tiffany shop online Says:

    cheap tiffany bracelets

Leave a Reply