Does daily aspirin have any preventive effect on prostate cancer?

There has been a great deal of media coverage in the past 24 hours about a study published in The Lancet Oncology. This study (a meta-analysis of numerous prior studies) suggests that a daily dose of aspirin may reduce risk for a variety of cancers.

It is not at all clear to us why there is such media fuss about this paper. It has been known for some time that daily aspirin can have a preventive effect on several gastrointestinal cancers — most particularly colorectal cancers. It has also been well understood that the benefit of taking daily aspirin to prevent colorectal cancer has to be balanced against the gastrointestinal risks of treatment with a daily aspirin regimen, which include the risk for gastrointestinal bleeding and other effects on the GI tract.

As far as we are aware, there is no good evidence to suggest that daily aspirin has any preventive effect when it comes to prevention of prostate cancer. There may be other good reasons to take a daily dose of aspirin for carefully selected patients. These include the known benefit of a “baby” aspirin each day to help prevent serious cardiovascular problems and the above-mentioned use of a daily aspirin to prevent colorectal cancers in persons at high risk for this type of cancer. However, men and women should be very clear that taking a daily aspirin for life comes with significant risk in the long  term. This is not a form of preventive care that should be undertaken without first having a serious conversation with a physician about the risk/benefit ratio for the individual in question, and we would be surprised if a meaningful number of physicians was under the illusion that a daily dose of aspirin would have any impact on risk for prostate cancer.

9 Responses

  1. Although the connection between aspirin and cancer is not new, I think it fair to say that it has provided a valuable step forward:

    This study had three main purposes: firstly to compare the results of observational studies (i.e., where a relationship, or correlation, has been observed between taking aspirin and improved outcome) and experimental studies (where a controlled experiment has been organised with half the subjects taking aspirin and half not taking it). This is important, as the massive evidence from observation (which must be taken as weaker than that gathered by a controlled experiment) was shown to correlate so closely with the experimental studies that it can now be taken to be valid.

    Secondly, the study did a meta-analysis of previous studies — i.e. the statisticians looked at numerous previous studies and drew out common findings (while making statistical allowances for differences in the various studies).

    Thirdly, the study looked at the impact of aspirin on cancers and groups not previously examined to see if it was equally effective, e.g breast cancer

    The outcomes were important in showing:

    (a) That we can accept that observational studies have valid results in this instance.

    (b) That meta-analysis shows agreement between observational and experimental studies, thus validating the former.

    (c) That the statistical probability of the researchers being wrong (i.e., the findings could be due to chance) are extremely low (see the probability figures, e.g., p < 0.0001 implying one chance in a thousand).

    I think it's fair to say this paper has made a worthwhile contribution to the literature.

  2. I took a full strength aspirin from age 40 to age 49, then an 81 mg aspirin from age 49 to present age (73). I had an RP at age 65. So did aspirin taken daily, even full strength, help prevent prostate cancer for me? I think not. I do believe in the benefits of daily aspirin, so I continue daily. We still don’t know what causes prostate cancer. How much is really in the genes, and how much is triggered by food, air, water, soft drinks, and diet?

  3. It looks like aside from the preventive aspect, aspirin is good at keeping prostate cancer at bay and reduces the risks substantially for developing metastasis while taking aspirin. Sounds like good news.

    “A second article by University of Oxford researchers published in The Lancet looked at the effect of aspirin on cancer metastasis (spread). They found that during an average 6½ years of taking aspirin (75 mg or more a day), trial participants lowered their risk of metastatic cancer by 36%. The main effect seemed to be on the risk of metastatic adenocarcinoma (a common type of solid cancer that can occur in many areas, including the colon, lung, and prostate), which was lowered by 46%. Researchers also found that daily aspirin lowered the risk of non-metastatic cancer progressing to metastatic cancer, especially in patients with colon cancer.”

  4. While there may be no studies regarding prevention, a study was presented at ASTRO in 2010 suggesting a daily aspirin reduces disease-specific mortality by 50% for prostate cancer patients. After reading this, I for one have since added an aspirin to my daily supplements.

    Here’s the link to an original report on Medscape.

  5. There are intriguing data suggesting that, particularly in high-risk patients, the addition of a daily aspirin to one’s therapeutic regimen may have a long-term effect on prostate cancer-specific survival. However, there are other data from studies that have shown no such effect.

    Frankly, without a well-controlled, randomized study, it is extremely difficult for any physician to make a recommendation on this matter one way or another. We also don’t know whether a low-dose, “baby” aspirin would work as well as a higher dose under such circumstances, and substantially reduce the risks associated with GI side effects.

    It should also be noted that the reduction in disease-specific mortality mentioned above in one (retrospective) analysis was a relative and not an absolute reduction in risk. The absolute reduction in risk was from 10% to 4% in that study at 10 years of follow-up in all patients but increased to an absolute reduction from 22% to 4% in high-risk patients.

  6. The discussion about the benefits of daily 100 mg aspirin tends to become conclusive for prostate cancer. However, the so-called NOSH aspirin might bring a real treatment option. See “NOSH-aspirin (NBS-1120), a novel nitric oxide- and hydrogen sulfide-releasing hybrid is a potent inhibitor of colon cancer cell growth in vitro and in a xenograft mouse model.”

    When does the randomized clinical trial (RCT) begin?!

  7. Pieter:

    I think I would like to see a couple of smaller, early stage trials of NOSH aspirin in prostate cancer patients before we start to argue for a Phase III RCT. Of course I don’t believe anyone will ever fund such an RCT … but that’s a whole different issue!

  8. Here are some simplifying thoughts that some people might find helpful:

    (A) If you already know that your gastrointestinal (GI) tract tolerates aspirin well, and if you are in a group that seems to benefit from taking aspirin, try taking a daily baby aspirin for a while. If you are not bothered by increased GI difficulties or bruising / slow clotting, it’s probably a helpful thing add to your long-term regimen. If you are in this group, then until and unless your personal experience or further studies provide more compelling evidence, you may want to ignore the focus on problems experienced by the 20% minority who are unlike you in this regard. (I happen to be in this group, what with my cast-iron stomach and quick-clotting blood, combined with my significant risk for both metastatic cancer and cardiovascular events over the next 20 years.)

    (B) If you already know that your personal biochemistry is such that aspirin causes you have bleeding problems or stomach-aches, then for you, the preventative effects are probably outweighed by the quality-of-life downsides, irrespective of the studies that look at general populations. If you’re in this group, then until and unless the studies provide much more compelling results, you may want to ignore the focus on what works for the 70% majority who are unlike you in this regard.

    (C) If you don’t fall in either camp A or camp B, then it’s probably a matter of personal style: Do you or don’t you take a 10% (20%?) risk of a [very minor?] decrease in quality-of-life in order to gain a 5% (30%?) chance of [slightly?] increasing your resistance to certain types of cancer problems and cardiovascular events much later in life?

    Of course, anyone thinking about embarking upon a lifelong regimen of medication should consult their physician, and should review their decision every year or so as new information comes to light. But when the risk of both harm and benefit is fairly low, personal style is probably more important than weighing the conflicting scientific/medical evidence for and against various low probabilities.

  9. Dear Sitemaster,

    Thank you for your reaction. As (almost always) prostate cancedrs belong to the family of adenocarcinomas, there is a rationale for early stage trials with NOSH aspirin in men with prostate cancer / CRPC. There is already evidence of a positive association between NSAIDs and prostate cancer. See for example, this paper in The Prostate from June 2011: Regression of prostate tumors upon combination of hormone ablation therapy and celecoxib in vivo.

    The investigators might ask for funding from the NCI and/or the PCF!

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