This is the kind of junk that gives science a bad name

So here comes a medical study with plenty of power–40,000 subjects so it has statistical significance. HOWEVER!!!!

Here’s the problem. The relative risk is miniscule, at 1.10 for prostate cancer rate and 1.19 for prostate cancer deaths.

So if the study was repeated there might be no effect. They said they adjusted for confounders? However you can’t adjust for randomness. They admit the absolute risk is miniscule, but they don’t admit the limits of an ecological observational epidemiological study. This ain’t no Randomized Controlled Trial.

People who get upset about cancer clusters suffer the same illiteracy, or is it innumeracy?

Vasectomy Linked to Prostate Cancer in 24-Year Study
RESEARCH · July 07, 2014


Analysis of 40,405 men from the Health Professionals Follow-Up Study found an increased risk for overall (HR, 1.10) and lethal (HR, 1.19) prostate cancer in men who underwent vasectomy, despite controlling for confounding factors. The overall risk for death from prostate cancer in the entire population was 1.6% over a 24-year follow-up period.
Although statistically significant, the increased association of prostate cancer and risk for death with vasectomy translates into a small absolute risk, and the biologic rationale behind the finding is unclear.
– Richard Bambury, MD



Conflicting reports remain regarding the association between vasectomy, a common form of male contraception in the United States, and prostate cancer risk. We examined prospectively this association with extended follow-up and an emphasis on advanced and lethal disease.


Among 49,405 US men in the Health Professionals Follow-Up Study, age 40 to 75 years at baseline in 1986, 6,023 patients with prostate cancer were diagnosed during the follow-up to 2010, including 811 lethal cases. In total, 12,321 men (25%) had vasectomies. We used Cox proportional hazards models to estimate the relative risk (RR) and 95% CIs of total, advanced, high-grade, and lethal disease, with adjustment for a variety of possible confounders.


Vasectomy was associated with a small increased risk of prostate cancer overall (RR, 1.10; 95% CI, 1.04 to 1.17). Risk was elevated for high-grade (Gleason score 8 to 10; RR, 1.22; 95% CI, 1.03 to 1.45) and lethal disease (death or distant metastasis; RR, 1.19; 95% CI, 1.00 to 1.43). Among a subcohort of men receiving regular prostate-specific antigen screening, the association with lethal cancer was stronger (RR, 1.56; 95% CI, 1.03 to 2.36). Vasectomy was not associated with the risk of low-grade or localized disease. Additional analyses suggested that the associations were not driven by differences in sex hormone levels, sexually transmitted infections, or cancer treatment.


Our data support the hypothesis that vasectomy is associated with a modest increased incidence of lethal prostate cancer. The results do not appear to be due to detection bias, and confounding by infections or cancer treatment is unlikely.

Journal of Clinical Oncology
Vasectomy and Risk of Aggressive Prostate Cancer: A 24-Year Follow-Up Study

J. Clin. Oncol 2014 Jul 07;[EPub Ahead of Print], MM Siddiqui, KM Wilson, MM Epstein, JR Rider, NE Martin, MJ Stampfer, EL Giovannucci, LA Mucci
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

5 responses to “This is the kind of junk that gives science a bad name

  1. So, if the overall risk is 1.6%, and the RR of having a vasectomy is 1.1, then the overall risk would be increased by 10% – to 1.8% after having a vasectomy (rounded up up). Wow. Lot’s to get scared about here.

  2. I’d bet as the study group aged, the risks increased.

  3. Here is another large study done over many years that showed no effects.
    (30,000+ subjects over 50 years)

    % of total deaths due to diseases ’caused’ by smoking

    Doll’s ‘doctors Study’ shows these facts; Table 1 on page 3:
    never-smokers have, per 1,000 people, 16.2 deaths from the diseases ’caused by smoking out of 19.38 total deaths per year
    That is 84%.

    Neversmokers = 84%

    Ex-cig smokers = 85%

    Current cig smokers = 85%

    Ex-pipe/cigar smokers = 85%

    Current pipe/cigar smokers = 84%

    Mortality in relation to smoking: 50 years observations on male British doctors
    Doll et al:

  4. It is possible for strong effects in individuals to register as insignificant in population aggregates. This happens when effects are diverse and not aligned. A great example is olfactory disturbance in pregnant women, most of whom claim that they experience drastic effects, while controlled population studies fail to demonstrate statistical significance in all but very small samples. Attempts to increase significance by increasing sample size typically leads to an even lesser significance. Statisticians doing these studies call such effects “idiosyncratic” and claim that there is no way to prove that pregnant women experience anything unusual. Sure, there is no way, if statistics is all they can do.

    Recently, it was shown that the first pregnancy activates neurogenesis in the olfactory bulb, accompanied by a100-fold increase in apoptosis. No wonder olfaction goes out of whack, and it does so in unpredictable and highly diverse ways. Statistics ignores everything that is out of whack. In this case, simply everything. There is no change in population means or whatever aggregates people are taught to use in med school.

    Theories explaining this mechanism are extremely interesting, but beside the point. It is always good to know the mechanism, rather than the value of some made-up aggregate measure of something possibly related to it.

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