VASECTOMY AND PROSTATE CANCER

Vasectomy and Risk of Prostate Cancer: A Systematic Review and Meta-analysis

Context

Previous reports have shown an association between vasectomy and prostate cancer (PCa). However, there exist significant discrepancies between studies and systematic reviews due to a lack of strong causal association and residual confounding factors such as prostate-specific antigen (PSA) screening.

Objective

To assess the association between vasectomy and PCa, in both unadjusted and PSA screen-adjusted studies.

Evidence acquisition

We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses. The PubMed, Scopus, and Web of Science databases were searched in January 2022 for studies that analyzed the association between vasectomy and PCa.

Evidence synthesis

A total of 37 studies including 16 931 805 patients met our inclusion criteria. A pooled analysis from all studies showed a significant association between vasectomy and any-grade PCa (odds ratio [OR] 1.23; 95% confidence interval [CI], 1.10–1.37; p < 0.001; I² = 96%), localized PCa (OR 1.08; 95% CI, 1.06–1.11; p < 0.00001; I² = 31%), or advanced PCa (OR 1.07; 95% CI, 1.02–1.13; p = 0.006; I² = 0%). The association with PCa remained significant when the analyses were restricted to studies with a low risk of bias (OR 1.06; 95% CI, 1.02–1.10; p = 0.02; I² = 48%) or cohort studies (OR 1.09; 95% CI, 1.04–1.13; p < 0.0001; I² = 64%). Among studies adjusted for PSA screening, the association with localized PCa (OR 1.06; 95% CI, 1.03–1.09; p < 0.001; I² = 0%) remained significant. Conversely, vasectomy was no longer associated with localized high-grade (p = 0.19), advanced (p = 0.22), and lethal (p = 0.42) PCa.

Conclusions

Our meta-analysis found an association between vasectomy and any, mainly localized, PCa. However, the effect estimates of the association were increasingly close to null when examining studies of robust design and high quality. On exploratory analyses including studies, which adjusted for PSA screening, the association for aggressive and/or advanced PCa diminished.

Patient summary

In this study, we found an association between vasectomy and the risk of developing localized prostate cancer without being able to determine whether the procedure leads to a higher prostate cancer incidence.

Impact of Vasectomy on the Development and Progression of Prostate Cancer: Preclinical Evidence

Some observational studies have implied a link between vasectomy and an elevated risk of prostate cancer. We investigated the impact of vasectomy on prostate cancer outgrowth, mainly using preclinical models. Neoplastic changes in the prostate were compared in transgenic TRAMP mice that underwent vasectomy vs. sham surgery performed at 4 weeks of age. One of the molecules identified by DNA microarray (i.e., ZKSCAN3) was then assessed in radical prostatectomy specimens and human prostate cancer lines. At 24 weeks, gross tumor (p = 0.089) and poorly differentiated adenocarcinoma (p = 0.036) occurred more often in vasectomized mice. Vasectomy significantly induced ZKSCAN3 expression in prostate tissues from C57BL/6 mice and prostate cancers from TRAMP mice. Immunohistochemistry showed increased ZKSCAN3 expression in adenocarcinoma vs. prostatic intraepithelial neoplasia (PIN), PIN vs. non-neoplastic prostate, Grade Group ≥3 vs. ≤2 tumors, pT3 vs. pT2 tumors, pN1 vs. pN0 tumors, and prostate cancer from patients with a history of vasectomy. Additionally, strong (2+/3+) ZKSCAN3 expression (p = 0.002), as an independent prognosticator, or vasectomy (p = 0.072) was associated with the risk of tumor recurrence. In prostate cancer lines, ZKSCAN3 silencing resulted in significant decreases in cell proliferation/migration/invasion. These findings suggest that there might be an association between vasectomy and the development and progression of prostate cancer, with up-regulation of ZKSCAN3 expression as a potential underlying mechanism.

Vasectomy and Risk of Prostate Cancer in a Screening Trial

Background: Vasectomy has been implicated as a risk factor for prostate cancer in multiple epidemiologic studies over the past 25 years. Whether this relationship is causal remains unclear. This study examines the association between vasectomy and prostate cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, which randomized men to usual care or annual prostate cancer screening.Methods: We performed a retrospective analysis of 13-year screening and outcomes data from the PLCO trial. Multivariable Cox proportional hazards regression stratified by study arm and age at vasectomy was performed.Results: There was an increased risk of prostate cancer in men who had undergone a vasectomy and were randomized to the usual care arm of the study (adjusted HR, 1.11; 95% confidence interval, 1.03-1.20; P = 0.008). There was no association between vasectomy and diagnosis of prostate cancer in men randomized to the prostate cancer screening arm. Only men undergoing vasectomy at an older age in the usual care arm of the study, but not the prostate cancer screening arm, were at increased risk of being diagnosed with prostate cancer.Conclusions: Vasectomy was not associated with prostate cancer risk among men who were screened for prostate cancer as part of a clinical trial, but was associated with prostate cancer detection in men receiving usual care.Impact: The positive association between vasectomy and prostate cancer is likely related to increased detection of prostate cancer based on patterns of care rather than a biological effect of vasectomy on prostate cancer development. Cancer Epidemiol Biomarkers Prev; 26(11); 1653-9. ©2017 AACR.

Vasectomy and risk of aggressive prostate cancer: a 24-year follow-up study

PURPOSE

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.

PATIENTS AND METHODS

Among 49,405 U.S. 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.

RESULTS

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.

CONCLUSION

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.

Regulatory T cells and vasectomy

CD4+ CD25+ regulatory T cells (Tregs) strongly influence the early and late autoimmune responses to meiotic germ cell antigens (MGCA) and the gonadal immunopathology in vasectomized mice. This is supported by the published and recently acquired information presented here. Within 24h of unilateral vasectomy (uni-vx) the ipsilateral epididymis undergoes epithelial cell apoptosis followed by necrosis, severe inflammation, and granuloma formation. Unexpectedly, vasectomy alone induced MGCA-specific tolerance. In contrast, uni-vx plus simultaneous Treg depletion resulted in MGCA-specific autoimmune response and bilateral autoimmune orchitis. Both tolerance and autoimmunity were strictly linked to the early epididymal injury. We now discovered that testicular autoimmunity in uni-vx mice did not occur when Treg depletion was delayed by one week. Remarkably, this delayed Treg depletion also prevented tolerance induction. Therefore, tolerance depends on a rapid de novo Treg response to MGCA exposed after vasectomy. Moreover, tolerance was blunted in mice genetically deficient in PD-1 ligand, suggesting the involvement of induced Treg. We conclude that pre-existing natural Treg prevents post-vasectomy autoimmunity, whereas vasectomy-induced Treg maintains post-vasectomy tolerance. We further discovered that vasectomized mice were still resistant to autoimmune orchitis induction for at least 12-16 months; thus, tolerance is long-lasting. Although significant sperm autoantibodies of low titers became detectable in uni-vx mice at 7 months, the antibody titers fluctuated over time, suggesting a dynamic "balance" between the autoimmune and tolerance states. Finally, we observed severe epididymal fibrosis and hypo-spermatogenesis at 12 months after uni-vx: findings of highly critical clinical significance.

Medical history, body size, and cigarette smoking in relation to fatal prostate cancer

OBJECTIVES

Prostate cancer has few known risk factors. As part of a population-based case-control study conducted in four health maintenance organizations, the authors examined the associations between fatal prostate cancer and several medical and behavioral characteristics.

METHODS

Cases were 768 health plan members who died of prostate adenocarcinoma during the period 1997-2001. We randomly selected controls (929) from the health plan membership and matched them to cases on health plan, age, race, and pattern of health plan membership. We examined medical records to obtain information on potential risk factors during the 10 years before the date on which prostate cancer was first suspected; the same reference date was used for the matched controls.

RESULTS

Anthropometric characteristics, as well as personal histories of benign prostatic hypertrophy, transurethral prostatectomy, cancer, diabetes, prostatitis, hypertension, and vasectomy were largely similar for cases and controls. Men who died from prostate cancer were more likely than controls to have been cigarette smokers according to the most recent smoking notation before the reference date (odds ratio 1.5, 95% confidence interval 1.1-2.0).

CONCLUSIONS

The observed increase in risk associated with recent cigarette smoking is consistent with the findings of several other studies. However, in contrast with some reports, we observed no connection between fatal prostate cancer and some prior health conditions or measures of body size.

Vasectomy and the risk of prostate cancer

PURPOSE

While the weight of evidence shows no association overall between vasectomy and prostate cancer, there has been some suggestion that an association may exist in subgroups, such as men who have a family history of prostate cancer, men who undergo vasectomy at a younger age or when several decades have passed since the procedure. Studies of risk with long latency periods have been hampered by small sample sizes in subgroups since vasectomy only became widely used in the 1960s and generally prostate cancer has a long latency period.

MATERIALS AND METHODS

We analyzed data from a recent population based case-control study that was designed specifically to address this issue of risk in subgroups. Interviews were completed with 1,001 men diagnosed with prostate cancer from January 1, 2002 through December 31, 2005 in the Seattle-Puget Sound region and in 942 matched control men. Subjects were black and white men between the ages of 35 and 74 years. Data were analyzed using unconditional logistic regression to calculate the OR as an estimate of the relative risk of prostate cancer associated with various vasectomy parameters.

RESULTS

The prevalence of vasectomy was similar in cases and controls (36.2% and 36.1%, respectively, adjusted OR 1.0, 95% CI 0.8-1.2). There were also no associations between prostate cancer and age at vasectomy, years elapsed since vasectomy or calendar year of vasectomy.

CONCLUSIONS

These findings indicate that there is no association between vasectomy and the risk of prostate cancer.

Association of Vasectomy and Prostate Cancer Among Men in a Maryland Cohort

OBJECTIVES

To evaluate the association of vasectomy with prostate cancer.

METHODS

Participants were male members of the CLUE II cohort followed since 1989. On a questionnaire mailed in 1996, the men were asked if they had had a vasectomy and their age at vasectomy. Between 1996 and April 2004, 78 prostate cancer cases were confirmed among the 3373 men who were at least 35 years old at baseline and who completed the questions about vasectomy. Cox proportional hazards regression was used to estimate age-adjusted hazard ratios (HR) of prostate cancer.

RESULTS

The HR for prostate cancer for men who had had a vasectomy was 2.03 (95% CI: 1.24-3.32). Risk of low-grade disease (HR=2.87; 95% CI 1.49-5.54), but not high-grade disease (HR=0.99; 95% CI 0.36-2.76), was higher in men who had had a vasectomy. No statistically significant associations were observed for low- or high-stage disease. The association for vasectomy was more pronounced in men who were 40 years at the time of vasectomy (HR=2.63; 95% CI 1.40-4.94) than in men who were younger at vasectomy.

CONCLUSIONS

The results from this prospective study suggest a positive association between vasectomy and prostate cancer, especially low-grade disease.

Cancer and cardiovascular disease after vasectomy: an epidemiological database study

OBJECTIVE

To determine whether vasectomy is associated with an increased long-term risk of cancer or cardiovascular disease.

DESIGN

Analysis of database of linked statistical records of hospital admissions and deaths.

SETTING

Health region in southern England.

PATIENT(S)

Men aged 20-59 years who were admitted to a hospital for vasectomy.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Rates of cancer and cardiovascular disease compared with the corresponding rates in a reference cohort, expressed as a rate ratio.

RESULT(S)

We found no elevation of risk, after vasectomy, of prostate cancer (rate ratio 0.74, 95% confidence interval [CI] 0.45-1.14) or other cancers. The rate ratio for coronary heart disease overall after vasectomy was 0.95 (95% CI 0.88-1.02); and the rate ratio > or =20 years after vasectomy was 0.98 (95% CI 0.80-1.19).

CONCLUSION(S)

Our findings add to the evidence that vasectomy is not associated with an increase in the long-term risk of these diseases.

Sexually transmitted diseases and other urogenital conditions as risk factors for prostate cancer: a case–control study in Wayne County, Michigan

OBJECTIVE To investigate associations between prostate cancer and sexually transmitted diseases (STDs), prostatitis, benign prostatic hyperplasia (BPH), and vasectomy in a population-based case-control study in Wayne County, Michigan, among African American and white men aged 50--74 years.

METHODS

Incident prostate cancer cases (n=700) from 1996--1998 were identified from the Metropolitan Detroit Cancer Surveillance System. Controls (n=604) were identified through random digit dialing and Medicare recipient lists, and frequency matched to cases on age and race. History of potential prostate cancer risk factors was ascertained through in-person interview.

RESULTS

Prostate cancer was not associated with STD or vasectomy history. History of prostatitis was associated with prostate cancer among all subjects (odds ratio [OR]=1.8, 95% confidence interval [CI]: 1.1, 2.9) and in African American men (OR=2.2, 95% CI: 1.1, 4.6). History of BPH was associated with prostate cancer among all subjects (OR=2.4, 95% CI: 1.8, 3.3); significant associations were observed in both African American (OR=2.7, 95% CI: 1.6, 4.4) and white (OR=2.3, 95% CI: 1.5, 3.4) men.

CONCLUSIONS

Among all subjects, prostate cancer was associated with prostatitis and BPH history, but not with STD or vasectomy history. Prevention efforts could be enhanced if inflammatory or infectious etiologies are found to be of importance in the subsequent development of prostate cancer.

[Vasectomy: study of 300 interventions. Review of the national literature and of its complications]

OBJECTIVES

The aims of this paper are: 1. To study the demand and reasons why of the vasectomy in area 12 of Valencian Community. 2. To analyse the adverse effects of our series and the predictable risk factors. 3. To review the adverse effects in the national series. 4. To review the adverse effects referred to in international publications.

PATIENTS AND METHODS

A retrospective study was made of 300 patients who had submitted themselves to a vasectomy between january 1992 and december 2000. All the clinical dossiers were reviewed according to 10 pre-established variables. age, number of offspring, reasons why, pre-vasectomy anticontraceptives; date of operation, type of anaesthesia used, pathologic anatomy, semen analysis after vasectomy, adverse effects and their possible causes (risk factors). The basic statistic study was done using a data base of Microsoft Access and the interpretations of the different variables using a table of Excel.

RESULTS

The demand for contraceptive attention (vasectomy) is the 8th cause for external urological consulting and the 4th for urological local ambulatory surgery of our area. 300 operations were done during that period. The average age of the patients was 37.5 years old (ranging from 25 to 51). The number of offspring ranged from 1 to 7, with a promedia of 2.41 children/patient. The reasons why were: voluntary family planning (86%), medical illnesses of the female which contraindicated gestation (9%), genetic reasons (4.33%) and social-sanitary problems (0.66%). Contraceptive methods used by 71.63% are known: The widest-used method being IUD (49.74%) and the preservative (25.88%). 30 patients (10%) had adverse effects, 29 patients having light adverse effects. The most frequent were: 12 orchiepididymitis (4%), 5 spermatic granulomas (1.66%), 3 chronic scrotal pain (1%), 2 scrotal haematoma (0.66%) and 2 bleeding (0.66%). There was one serious complications and of all the cases mentioned above only one needed hospitalization (impetigo-sepsis) and another needed surgery due to a spermatic granuloma. There were no pregnancies or post-vasectomy court cases. 81% of the patients had been declared azoospermic within 45 to 60 days after the vasectomy in one or two consecutive semen analysis.

CONCLUSIONS

The vasectomy is a safe and simple way for male sterilization. It's the most widely done urologic operation in Spain. The technique isn't extent of adverse effects (0 to 18%) and its seriousness varies from a simple ecchymosis to Fournier's gangrene, endocarditis or sepsis. A doctor would be considered negligent if he/she didn't inform the patient about the remote possibility of a spontaneous recanalisation of the vas deferens leading to renewed fertility (failure of the vasectomy). It is imperative to give post-vasectomy information where the patient must continue using his habitual anticonceptive method until the azoospermia shown in 2 semen analysis confirm the sterility of the patient so that the urologist has no legal problem.

Vasectomy and the risk of prostate cancer: a meta-analysis examining vasectomy status, age at vasectomy, and time since vasectomy

The aim of this study was to conduct a quantitative review of prostate cancer studies to pool relative risk (RR) estimates on the association between prostate cancer and vasectomy, in an attempt to determine whether there is an association, and if so, its magnitude. Random-effects models were examined along with a linear model for time since vasectomy. The pooled RR estimate was 1.37 (95% CI=1.15-1.62) based on five cohort studies and 17 case-control studies. The RR estimate varied by study design with the lowest risk for population-based case-control studies. No difference was seen in risk by age at vasectomy. A linear trend based on the 16 studies reporting time since vasectomy suggested an 10% increase for each additional 10 y or a RR of 1.32 (95% CI=1.17-1.50) for 30 y since vasectomy. When null effects were assumed for the six studies not reporting information, the linear RR for the 22 studies was 1.07 (1.03-1.11) and 1.23 (1.11-1.37) for 10 and 30 y since vasectomy, respectively. These results suggest that men with a prior vasectomy may be at an increased risk of prostate cancer, however, the increase may not be causal since potential bias cannot be discounted. The overall association was small and therefore could be explained by bias. The latency effect shown here for time since vasectomy should be examined further.

Vasectomy and prostate cancer characteristics of patients referred for prostate biopsy

PURPOSE

The prospect of an association between vasectomy and prostate cancer has gained widespread attention and has potentially influenced patterns of referral. In patients referred for prostate needle biopsies we compared the incidence and characteristics of prostate cancer in those reporting a history of vasectomy to those denying prior vasectomy.

MATERIALS AND METHODS

A total of 585 consecutive prostate biopsy procedures were performed on 522 veterans during a 42-month period. Upon questioning 101 patients (19.3%) reported prior vasectomy. From the remaining 421 patients 202 consecutive age matched controls were selected. Pre-procedure prostate specific antigen levels, digital examination findings, incidence of prostate cancer, cancer grade and tumor length on biopsy cores were compared between the patients with and without a history of vasectomy.

RESULTS

Of the 101 patients who reported a history of vasectomy 46 (45.5%) had prostate cancer compared to 98 (48.5%) of the 202 age matched controls, and this difference was not statistically significant. Of the patients with prostate cancer those with prior vasectomy less frequently had an abnormal digital examination and lower prostate specific antigen levels, lower Gleason grade, lower clinical stage and shorter length of cancer on biopsies.

CONCLUSIONS

We found no increase in prostate cancer incidence or severity in patients referred for prostate biopsy who had undergone prior vasectomy. In fact, prostate cancer was less common with fewer poor prognostic indicators in patients with previous vasectomy. These findings may be secondary to either selection bias, as patients with a vasectomy may seek more routine medical care, or a greater tendency of primary providers to refer these patients for evaluation.

Response of the adult prostate to prepubertal and postpubertal obstruction of the vas deferens in the rat

OBJECTIVES

To determine whether obstruction of the vas deferens alters several general measures of prostate development during puberty and during prostate maintenance in the adult rat. Previous reports have suggested the possibility that vasectomy results in alterations of prostate function in experimental animals and humans.

METHODS

Adult rats and 10-day-old rats were subjected to bilateral sham operations or bilateral vasectomy, and the prostates were extirpated either 14 or 60 days later. The total prostate weight and dorsolateral and ventral lobe total protein per milligram tissue, DNA per milligram tissue, and DNA per milligram protein were determined. Dorsolateral and ventral prostate lobe sections from each group were also stained with hematoxylin-eosin and subjected to histologic examination.

RESULTS

The histologic features of the adult rat prostate were not qualitatively altered by vasectomy whether it occurred before puberty or in adult animals with mature prostates. Furthermore, vasectomy did not significantly alter the prostate weight or the protein or DNA content of either the dorsolateral or ventral lobes of the prostate compared with the sham-operated animals of either age.

CONCLUSIONS

Vas deferens obstruction does not significantly alter the parameters associated with the development or maintenance of the adult rat prostate measured in this study.

Vasectomy and prostate cancer in Québec, Canada

The present investigation measured the association between vasectomy and prostate cancer (PC) in the male population of Québec, Canada. The Québec Health Insurance Board and the Québec Cancer Registry were our principal sources of information. Lung cancer cases and the male population of Québec served as controls for comparative purposes. Within a retrospective design, our preliminary results indicate an association between vasectomy and PC. Among the 1925-39 birth cohort of individuals diagnosed with PC in 1990--93, the global odds ratio was 2.6 (95% CI=1.7--4.3) while it was compared with lung cancer as the control group. This risk increased with the length of time between vasectomy and the diagnosis of cancer. An historical design indicated strong cohesion of the results. Besides, the risk does not vary when we control for the place of residence of the individuals. Vasectomy seems to increase the risk of PC at least 10 years after the operation, but we cannot exclude the impact of a possible detection bias among vasectomized individuals.

Vasectomy

Vasectomy is regarded as the safest method now available for male fertility control. Almost 100 million men worldwide have relied on vasectomy for family planning. This review discusses all currently relevant operative techniques, including no-scalpel vasectomy, complications, possible long-term effects on the testis and epididymis, and diseases for which associations with vasectomy have been suggested, such as arteriosclerosis, autoimmune diseases and cancer of the prostate and testis. Other topics of discussion include the timing of post-operative semen analysis, patient noncompliance concerning post-operative controls, persistent cryptozoospermia and transient reappearance of spermatozoa after vasectomy, vasectomy failure and legal aspects.

Vasectomy. A safe, effective, economical means of sterilization

Vasectomy is a common office procedure that is a permanent, safe, and effective form of birth control. It is less expensive and safer than tubal ligation. Physicians who wish to perform the procedure should be aware of the potential complications and explain them to the patient. Physicians also should perform the procedure often enough to have a low complication rate.