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Prostate Cancer Not Related to Vasectomy
Vasectomy Remains a Simple and Safe Method of Birth Control: The Latest Information Regarding Vasectomy and Prostate Cancer
Dr. Eric K. Seaman MD

Vasectomy is a simple, safe, and effective means of permanent birth control or sterility. Each year about one-half million men in the United States choose vasectomy as their method of birth control.

How a vasectomy works
Sperm are made in the testes and stored in the distal portion of the epididymis. At the time of ejaculation, sperm travel through the vas deferens out through the ejaculatory ducts, (joined by fluid from the prostate and seminal vesicles) and out through the urethra. A vasectomy divides the vas and interrupts the sperm from getting to the ejaculatory ducts. Because most of the fluid in the ejaculate is made in the seminal vesicles and prostate, even after vasectomy, the ejaculate volume will be maintained.

The vasectomy procedure:
Vasectomy is generally performed in the office. The procedure takes about 30 minutes. Patients are given a local anesthetic and a sedative by mouth. No-scalpel vasectomy techniques have been popularized; however, the major difference of this technique is to use a sharp clamp, rather than a scalpel to make the skin opening. A portion of the vas is generally removed. The ends of the vas are clipped and sealed by heat (cauterized) to prevent auto-reversal. It takes about fifteen ejaculations to clean out all the residual sperm from the ejaculatory ducts. Two negative semen analyses are required after the procedure before patients are allowed to have unprotected relations.

Vasectomy and Prostate Cancer
In the past 10 years, there have been 14 major studies investigating a possible relationship between vasectomy and prostate cancer have been published. These studies were reviewed in the August, 1998 issue of Fertility and Sterility (Bernal-Delgado et al; p 191-200). Only 6 studies found a statistically significant association; however, all of the studies were found to have significant methodologic problems, especially the 6 studies.

Methodologic problems included bias in selection of study participants, in obtaining information about the participants and in confounding the vasectomy-prostate cancer relationship. For example, men who have their vasectomy performed by a urologist may be see a urologist more often than men who have not, and therefore may have an assymptomatic cancer picked up ealier. Studies of mortality after vasectomy suggest that men who undergo vasectomy in the US may in general, be healthier than their counterparts who do not (Giovannucci et al, NEJM 1992:326:1392).

Finally, there is little evidence for a possible biologic explanation as to why the 2 might be associated. For example, vasectomy has been reported to increase serum testosterone, but such increases are small if they occur at all and serum levels stay within the normal range. Antisperm antibodies are also generated after vasectomy; however any implication of their role in initiating carcinogenesis is yet to be proven.

The Controversy about the possible association began with a hospital based case control study. 220 men diagnosed with prostate cancer were compared with 2 control groups: one group consisted of men admitted for taurma or appendicitis. Comparison with this group revealed a relative risk of 5.3; there is an obvious confounding variable, here, in that the control group might be inappropriate because of the tendency to include younger patients or patients who might not seek vasectomy. (Guess HA: Am J Epidemiol, 1990:132:1062)

Sidney et al performed a cohort study of members o the Northern California Kaiser Permanente Medical Care Program. The study compared 5332 men with a history of vasectomy with 3 times as many non-vasectomized men match for age race marital status and date and location of the examination. The relative risk discovered for the 2 groups was 1.0. However, Giovannucci subsequently reported 2 cohort studies revealing an increased relative risk for vasectomized men. One study was a retrospective review based on husbands of women in the Nurse's' health study. The history of vasectomy and of cancer was obtained from the wives. 29214 subjects were involved with study and a relative risk of 1.6 was reported for vasectomized individuals.

Publication of the 2 Giovannucci studies prompted the NIH to convene an expert panel to provide recommendations to clinicians and public health authorities based on all available biologic and epidemiologic evidence concerning vasectomy and prostate cancer. The panel concluded that the associations that have been found are weak and that detection bias cannot be ruled out. They reported the following conclusions (Healy B: JAMA 1993;269:2620)

  1. Health-care providers should continue to offer vasectomy and perform the procedure
  2. Vasectomy reversal is not warranted to prevent prostate cancer.
  3. Screening for prostate cancer should not be any different for men who have had a vasectomy than for those who have not.