Vasectomy and prostate cancer — the debate evolves

As regular readers will be well aware, the question of whether there is a real cause and effect association between having a vasectomy and the later risk for diagnosis of prostate cancer is controversial and unanswered in any absolute sense. However, there are new data that we can now put on the table …

In an article in the Journal of Clinical Oncology, Siddiqui et al. have provided information based on a 24-year follow-up analysis of data from the Health Professionals Follow-Up Study (HPFUS)  here in the USA. Their analysis was designed to look specifically at the potential for an association between vasectomy and the occurrence not of a simple diagnosis, but the occurrence of advanced prostate cancer or actual prostate cancer-specific mortality (i.e., lethal disease).

The HPFUS originally enrolled 49,405 men, all aged between 40 to 75 years at baseline in 1986. Of those 49,405 men, a total of 12,321 (24.9 percent) had vasectomies; 6,023 (12.2 percent) were subsequently diagnosed with prostate cancer during the follow-up period (i.e., through December 31, 2010); and 811 (1.6 percent) actually died of prostate cancer.

Siddiqui et al. report that:

  • Vasectomy was associated with a small overall increase in risk for prostate cancer overall (relative risk [RR] = 1.10).
  • This relative risk level was a little higher among
    • Men diagnosed with a Gleason score  of 8 to 10 (RR = 1.22)
    • Men who actually died of prostate cancer or had distant metastasis (RR = 1.19)
  • Among men receiving regular PSA screening, the association between a vasectomy and risk for lethal cancer was stronger (RR = 1.56).
  • There was no association between vasectomy and risk for low-grade or localized disease.
  • There was no apparent evidence that these associations were a consequence of differences in
    • Sex hormone levels
    • Sexually transmitted infections
    • Type(s) of cancer treatment

Siddiqui et al. conclude that their 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.

The strength of this study is clearly in the long follow-up period. There does seem to be a modest increase in risk for aggressive and potentially lethal prostate cancers associated with having a vasectomy in this cohort of patients. But this study still doesn’t give us any clear idea of whether the effect is related to the vasectomy itself or to some other (possibly but not certainly related) cause.

What is not immediately apparent from the abstract of this paper is the absolute increase in risk for aggressive and potentially lethal prostate cancer from having a vasectomy. In other words, of the 811 men who actually died of prostate cancer in this study, how many had had a vasectomy and how many had not, and what was the time from a vasectomy to diagnosis or metastatic disease or actual prostate cancer death? These data may be available in the full text of the paper, but we have not seen that (as yet).

One Response

  1. FYI … I had a vasectomy in 1991. It does seem that I have lethal cancer. Lots of other factors I am sure — but I seem to fit the pattern.

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