Vasectomy and risk for prostate cancer all over again


Over the years there has been controversy as to the existence of an association between vasectomy and risk for prostate cancer. A new set of data from a large, long-term study, to be presented at the upcoming annual meeting of the American Society of Clinical Oncology, has shown that there is, indeed, such a risk — but it is specific to high-risk prostate cancer.

The paper by Mucci et al. is based on data from 49,432 male participants in the US Health Professionals Follow-up Study, which started in 1986 and followed the participants for 24 years until 2010. All participants were between 40 and 75 years of age at time of enrollment.

Here are the core data from the study:

  • 6,398/49,432 men (12.9 percent) were diagnosed with incident cases of prostate cancer.
  • 12,371/49,432 men (25.0 percent) met criteria implying that they were “highly screened” for risk of prostate cancer.
  • 22 percent of the 49,432 men had had a vasectomy at baseline.
  • Of the 6,398 men diagnosed with prostate cancer
    • 734 (11.5 percent) were diagnosed with high-grade cancer (Gleason score 8 to 10).
    • 813 (12.7 percent) had a lethal form of prostate cancer (i.e., cancer that metastasized or caused their death).
  • Among the men who had had a vasectomy at baseline (compared to those who had not), there was
    • An increased risk of high-grade prostate cancer (hazard ratio [HR] = 1.23)
    • An increased risk of lethal prostate cancer (HR = 1.20)
  • The risk of lethal prostate cancer was higher among men who had a vasectomy before age 38 years compared with men receiving vasectomies at older ages.
  • Among the men who were “highly screened” for risk of prostate cancer (compared to those who were not), there was
    • An increased risk of high-grade prostate cancer (HR ~ 1.20)
    • An increased risk of lethal prostate cancer (HR = 1.56).
  • The increases in risk associated with vasectomy could not be explained by differences in hormone levels, prevalence of sexually transmitted infections, or cancer treatments.

The authors conclude that, “Data from this study support the hypothesis that vasectomy is associated with a small increased incidence of aggressive prostate cancer defined as high grade cancer and disease causing death or bony metastasis. Differences in diagnostic intensity or confounding bias do not explain this elevated risk.”

Now it should immediately be noted that the authors do not either suggest or imply that there was any evidence of an overall increase in risk for prostate cancer associated with vasectomy. Their findings are exclusively confined to an association between vasectomy and high-risk disease. On the other hand, of course, it is this type of high-risk prostate cancer (the type that kills you or causes metastasis) that men are trying to avoid the most.

As far as The “New” Prostate Cancer InfoLink is aware, this is the first study to suggest that there is an association between vasectomy and high-risk prostate cancer, and it is certainly based upon a large, carefully monitored database.

To put these data into “real numbers” it is telling us that, for every 10,000 men in the USA between the ages of 40 and 75,

  • 1,290 will be diagnosed with prostate cancer.
  • About 323 of those men may be “highly screened.”
  • Of the total of 1,290 patients, about 164 will have a lethal form of the disease.
  • Of the 323 men with prostate cancer who were “highly screened,” 41 will have a lethal form of the disease, of whom about 24 had a vasectomy and about 16 didn’t.
  • Of the 967 men with prostate cancer who weren’t “highly screened,” 123 will have a lethal form of the disease, of whom about 67 had a vasectomy and about 56 didn’t.

Is this enough to tell a man he shouldn’t have a vasectomy?

That’s a very personal decision and needs to be compared to all the upsides and downsides of not having a vasectomy (perhaps more children; perhaps a spouse dying in childbirth; perhaps a spouse staying on “the pill” for another 10 or 20 years, with all the associated risks; etc.).

6 Responses

  1. Whoa … wait a minute … my primary doctor, yesterday, strongly said, “They have finally debunked the vasectomy and prostate cancer relationship!”

    The article “links” vasectomy and “the high-end” cancer. What are the studies showing involving “low end” or the middle range prostate cancer? Any relationships?

  2. Richard:

    See “Does having a vasectomy cause prostate cancer?” (which we shall now need to upodate).

  3. None of the data says that vasectomies cause cancer. Only that there is an association (epidemiological study). Who knows, it could be that vasectomized men have a greater tendency to have unprotected sex with women that may be carrying some virus that causes prostate cancer. Note: It is not yet known whether there is a virus that causes prostate cancer, but there could be.

  4. Dear Don:

    One of the upsides of our ability to carry out DNA and RNA sequencing is that it makes it a great deal easier to identify the presence/absence of viruses and other microorganisms that may be implicated in the initiation of human disorders from rheumatism to AIDS. While it is certainly the case that viruses are involved in the origin of some cancers, there appears to be less and less evidence to support a viral origin for prostate cancer. This certainly could still be the case for some forms of prostate cancer, but the probability seems to be declining by the year.

    With respect to the suggestion that vasectomized men might have a tendency to have unprotected sex with women carrying such a virus, … I doubt it. Many men who have vasectomies show significant evidence of being monogamous.

  5. “The increased risks with vasectomy could not be explained by differences in hormone levels, prevalence of sexually transmitted infections, or cancer treatments.”

    In Dr. Mucci’s abstract in her poster session, no mention was made of the age distribution of cancer diagnosis, body habitus, race, family history, smoking history, and/or diet.

    The study followed men up to 24 years with an age span of 40 to 75. We do not have any data on the comparability of men choosing vasectomy and those not choosing it. Is there anything about a man who chooses a vasectomy?

    You bet there is. …

    Thew following abstract of an article entitled “The American man who chooses vasectomy: a profile” appeared in AVSC News. 1988;26(1):3 (no authors were listed):

    “Who is the typical American man choosing vasectomy? The evidence from studies is clear. He is most likely to be white, to live in the West, and to be better educated and have a higher income than the average. He is in his mid- to late thirties and has at least 1 son. He has been actively involved in birth control and strongly dislikes other contraceptive methods. Vasectomy, to him, is a matter of convenience. He is more strongly motivated than his wife to end childbearing and is protective of his wife’s health. He is secure, with lower than average need for social approval. How does he arrive at a decision? American men take a long time to make a decision about vasectomy. The process may last anywhere from 2 to 10 years. Stephen Mumford has outlined a 7-step decision making process. A man: becomes aware of vasectomy, talks to a vasectomized man, decides to have no more children, seriously considers vasectomy, decides temporary methods are no longer acceptable, decides vasectomy is the best method, has a pregnancy “scare”. Then the man schedules an appointment with his doctor.”

    So let’s re-run the data again, Dr. Mucci.

  6. Vasectomy in most cases may not cause prostate cancer. However, if a man has prostate cancer or early forms of prostate cancer and he had a vasectomy the chances of the cancer becoming aggressive would be greatly increased. So it depends on how the question is asked. As people’s lifespan increases, at some point more men are going to get prostate cancer and for those who had a vasectomy their cancers are going to be more aggressive and may even occur sooner than men who had not.

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