The coffee saga continues … without much expectation of real clarity


As we mention regularly, there is a big difference between an association of behavior X or diet Y with risk for a specific disorder and the idea that behavior X or diet Y might help to cause or help to prevent that disorder in a specific group of people.

The continuing saga of whether drinking coffee does or doesn’t really have any particular effect on risk for prostate cancer in highly identifiable individuals is a case in point.

The latest contribution to this saga is a paper by Geybels et al. study published online on August 2 in Cancer Causes and Control. A readable commentary on this study is also available on the Medscape Oncology web site.

The problem with all studies of the type described is that what it can not tell us is almost as important as what it can tell us!

The study was based on self-reported information about coffee and tea consumption prior to diagnosis among 630 men diagnosed with prostate cancer who were treated and then monitored for recurrence or progression over a median period of 6.4 years. The authors report that:

  • 140/630 cases of  prostate cancer recurrence/progression were recorded (a 22 percent biochemical recurrence rate).
  • 61 percent of patients consumed at least one cup of coffee per day prior to diagnosis.
  • Coffee consumption prior to diagnosis was associated with a reduced risk of prostate cancer recurrence/progression.
  • Compared to patients who drank no more than 1 cup of coffee per week
    • Men who drank 4 or more cups of coffee per day were much less likely to have progressive disease (adjusted hazard ratio [HR] = 0.41).
  • There was no evidence of any association between tea drinking prior to diagnosis and increased or decreased risk of prostate cancer recurrence/progression (but only 14 percent of patients drank 1 or more cups of tea per day).

The authors state that their data are “consistent” with the data from those found in the Health Professionals Follow-up Study cohort, However, they also go on to note that:

  • “[I]ncreasing one’s coffee intake may be harmful for some men” (e.g., men with hypertension).”
  • “[S]pecific components in coffee may raise serum cholesterol levels, posing a possible threat to coronary health.”
  • They do not know whether the patients in this study were drinking caffeinated or decaffeinated coffee prior to diagnosis.
  • They had no information about how the coffee was being prepared (espresso, boiled, filtered, instant, you name it).
  • They have no information about the strength of the coffee people were drinking.

Futhermore, there are no data in the abstract about the consumption of coffee or tea after diagnosis and treatment.

The bottom line — as we understand it today — is that there does seem to be “some sort” of association between drinking coffee in relatively large quantities and a reduction of risk for diagnosis, progression, and death from prostate cancer. However, drinking large quantities of coffee on a regular basis (particularly strong, “real” — as opposed to instant — coffee) may well have other less beneficial effects over time too.

On the one hand the authors want to emphasize that “clinicians should not recommend coffee or specific coffee components for the secondary prevention of prostate cancer.” On the other they argue that large prospective studies (requiring large amounts of money) are “urgently needed” to investigate whether drinking coffee can help men diagnosed with prostate cancer.

If large amounts of money were even available for prostate cancer research at the present time, The “New” Prostate Cancer InfoLink thinks there might be better ways to spend that money than on a 10-year-long, prospective trial in thousands of participants in the hope that we might be able to establish categorically whether coffee-drinking can affect risk for prostate cancer progression. (Actually such a study might require tens of thousands of participants.) The inherent difficulties associated with the rigorous conduct of such a trial are enormous! Just look at the data that we got from the Prostate Cancer Prevention Trial and from the SELECT trial. These two trials cost us a fortune … but neither one was able to provide us with positive, “game changing” data about how to prevent prostate cancer.

2 Responses

  1. AND WHAT IF JUST CONSUMING MORE LIQUID MAKES A DIFFERENCE?

    As a heavy green tea consumer (at least 8 bags worth per day — 2 bags per 12 ounce coup, acidified with about 8 drops of lemon juice each, brewed for at least 5 minutes and stirred) for years, I’ve wondered if just the amount of liquid consumed could be making a difference. I have actually tracked my own hydration levels (mainly water, green tea, coffee, plus V8) for years, but I suspect I’m in a tiny minority who do that. LOL (Is that Sitemaster I hear chuckling?)

    For kicks I did a quick check of PubMed, using two search strings: “prostate cancer AND liquid consumption”, which yielded 26 hits, none very helpful, and “prostate cancer AND water consumption”, which yielded 414 hits, way more than I care to review. Putting “water” in quotes reduced this to 32 hits, none looking particularly relevant. “prostate cancer AND hydration” produced 36 hits, again with none looking relevant. The hits often relate to green tea, coffee, or lycopene consumption; I doubt that any relate to the quantity of total liquid as the key variable. I also tried a look at any cancer with “cancer AND hydration NOT parenteral”, which yielded 216 hits after selecting only clinical trial papers with abstracts. A check of the first couple of pages yielded nothing helpful, nor did other filters (human, title) help.

    As with investigating the effects of coffee, sorting out the independent effects of hydration looks to me to be impossible. Ever hopeful, I’m thinking some kind of proxy might yield some insight, if some researcher were bold enough to try. I have a hunch that hydration does make some kind of difference, as, for instance, in drug delivery.

  2. I’ll drink to that ! :)

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