Incidence of disease after vasectomy: a record linkage retrospective cohort study

The review of the long-term health risks associated with vasectomy

Vasectomy, a permanent method of preventing the release of sperm, has been widely used as effective birth control, with millions of men undergoing the procedure worldwide each year. Although vasectomy is effective and relatively simple, it is still a subject that receives considerable scrutiny, especially regarding any health effects. Indeed, the relationship between vasectomy and health risks has been a controversial topic. This review includes the examination of the evidence linking vasectomy to oncologic sequelae (i.e. prostate and testicular cancer). In addition, a review of the literature linking vasectomy to sexual dysfunction, cardiovascular disease, primary progressive aphasia/frontotemporal dementia, anti-sperm antibodies, and reproductive hormone changes is also presented. Overall, vasectomy appears safe with no convincing evidence for long term health risks.

Vasectomy and prostate cancer risk: a pooled of cohort studies and Mendelian randomization analysis

BACKGROUND

The relationship between vasectomy and the risk of prostate cancer (PCa) remains unclear, with observational studies reporting inconsistent results. To clarify this ambiguity, we embarked on a comprehensive investigation comprising both a meta-analysis and a Mendelian randomization (MR) study. This dual approach aimed to thoroughly examine not only the association but also the causality between undergoing a vasectomy and the subsequent risk of PCa.

METHODS

Our systematic review meticulously examined cohort studies published until January 2024, employing a random effects model for the computation of relative risks (RR) and their 95% confidence intervals (CI). For MR Analysis, we leveraged aggregated data from the IEU Open GWAS database, investigating the correlation between genetic predisposition to vasectomy and PCa. We chose single nucleotide polymorphisms (SNPs) of European descent as instrumental variables (IVs) for this analysis. The primary method for calculating the odds ratios (ORs) and their 95% CIs was inverse variance weighting (IVW). Through sensitivity analysis, we confirmed the robustness of our findings.

RESULTS

Our investigation synthesized data from 19 cohort studies, encompassing over four million participants. The combined analysis revealed a statistically significant link between vasectomy and an elevated risk of PCa across any grade (RR = 1.09; 95%CI: 1.05-1.14; P = 0.001; I² = 83.3%). This association was observed for both localized PCa (RR = 1.08; 95% CI: 1.04-1.13; P < 0.001; I² = 48.8%) and advanced PCa (RR = 1.07; 95% CI: 1.01-1.13; P = 0.016; I² = 0%). Nonetheless, the discovery cohort MR Analysis indicated no genetic causal link between vasectomy and PCa (OR = 0.067; 95%CI = 0.002-1.535; P = 0.09). A validation set in the Finnish population confirmed the robustness of the results. This conclusion remained consistent even after controlling for variables such as prostate-specific antigen (PSA) testing and body mass index (BMI), suggesting that while a statistical association exists, the genetic evidence does not support a causal relationship.

CONCLUSION

The cumulative analysis indicates a possible elevated risk of PCa in patients who have had a vasectomy. However, MR Analysis has not confirmed a direct causal link between vasectomy and PCa. This suggests that the association observed may not stem from direct causation, allowing for the continued consideration of vasectomy as a viable long-term contraceptive choice. Further research is imperative to uncover any factors that could potentially link vasectomy to an increased risk of prostate cancer, aiming to provide a more comprehensive understanding of the implications.

[Male contraception]

CONTEXT

Contraception is a major global health issue, which is still dominated by female contraception. Developments in male contraception could help redistribute the contraceptive burden.

METHODS

A literature search was carried out to review the existing options and the criteria for optimal contraception, to establish the principles of a male pre-contraception consultation, and to review the various research avenues with their advantages and disadvantages.

RESULTS

The new male contraception options are detailed, whether hormonal (androgen therapy, combination of progestins and testosterone) or non-hormonal, particularly thermal, with current results and avenues for improvement. Condom use and vasectomy remain the only 2 validated options. The recent development of minimally invasive vasectomy without the need for a scalpel and of occlusion techniques has simplified the procedure, minimised the risk of complications (pain, haematomas, post-vasectomy pain syndrome) and improved efficacy. The issues of regret and the possibility of repermeabilisation are also raised.

CONCLUSION

The question of male contraception will become increasingly important in consultations with urologists. The urologist will have to inform the patient, as required by law, before the vasectomy is performed, and provide the best possible advice on the technique, which will often be minimally invasive without the need for a scalpel. New reversible options should also broaden the range of options available on a routine basis, with a view to gradually moving towards contraceptive equity.

[Recommendations of the Committee of Andrology and Sexual Medicine of the AFU concerning the management of Vasectomy]

OBJECTIVES

To answer the main clinical questions asked by practitioners and men consulting for a vasectomy request.

METHOD

The CPR method was used. The clinical questions were formulated according to the PICO methodology. A Pubmed literature search for the period 1984-2021 identified 508 references, of which 79 were selected and analyzed with the GRADE grid.

RECOMMENDATIONS

Vasectomy is a permanent, potentially reversible contraception. It is a safe procedure. A second vasectomy is necessary in only 1 % of cases. Surgical complications (hematoma, infection, pain, etc.) are rare. The frequency of prolonged scrotal pain after vasectomy is about 5 %, and less than 2 % describe a negative impact of this pain on their quality of life. Vasectomy does not have negative consequences on sexuality. The only contraindication to vasectomy is the minor patient. Patients at increased risk of remorse are single, divorced or separated men under the age of 30. Sperm storage may be particularly appropriate for them. Whatever the reason, the law allows the surgeon to refuse to perform the vasectomy. He must inform the patient of this at the first consultation. The choice of the type of anesthesia is left to the discretion of the surgeon and the patient. It must be decided during the preoperative consultation. Local anesthesia should be considered first. General anesthesia should be particularly considered in cases of anxiety or intense sensitivity of the patient to palpation of the vas deferens, difficulty palpating the vas deferens, or a history of scrotal surgery that would make the procedure more complex. Concerning the vasectomy technique, 2 points seem to improve the efficiency of the vasectomy: coagulation of the deferential mucosa and interposition of fascia. Leaving the proximal end of the vas deferens free seems to reduce the risk of post-vasectomy syndrome without increasing the risk of failure or complications. No-scalpel vasectomy is associated with a lower risk of postoperative complications than conventional vasectomy. Regarding follow-up, it is recommended to perform a spermogram at 3 months post-vasectomy and after 30 ejaculations. If there are still a few non-motile spermatozoa at 3 months, it is recommended that a check-up be performed at 6 months post-vasectomy. In case of motile spermatozoa or more than 100,000 immobile spermatozoa/mL at 6 months (defining failure), a new vasectomy should be considered. Contraception must be maintained until the effectiveness of the vasectomy is confirmed.

Association between vasectomy and risk of testicular cancer: A systematic review and meta-analysis

Objectives

A number of researchers have reported that vasectomy is a risk factor for testicular cancer. However, this conclusion is inconsistent with a number of other published articles. Hence, we conducted this meta-analysis to assess whether vasectomy increases the risk of testicular cancer.

Materials and methods

We identified all related studies by searching the PubMed, Embase, and Cochrane Library database from January 01, 1980 to June 01, 2017. The Newcastle-Ottawa Scale (NOS) checklist was used to assess all included non-randomized studies. Summarized odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the difference in outcomes between case and control groups. Subgroup analyses were performed according to the study design and country.

Results

A total of eight studies (2176 testicular cancer patients) were included in this systematic review and meta-analysis. Six articles were case-control studies, and two were cohort studies. The pooled estimate of the OR was 1.10 (95% CI: 0.93–1.30) based on the eight studies in a fixed effects model. Two subgroup analyses were performed according to the study design and country. The results were consistent with the overall findings. Publication bias was detected by Begg’s test and Egger’s test and p values > 0.05, respectively.

Conclusions

Our meta-analysis suggested that there was no association between vasectomy and the development of testicular cancer. More high-quality studies are warranted to further explore the association between vasectomy and risk of testicular cancer.

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 prostate cancer risk: a historical synopsis of undulating false causality

The potential influence of vasectomy being a risk factor for the development of prostate cancer is not a new concept, with more than 30 publications addressing the topic. Given the global frequency of vasectomy and the prevalence of prostate cancer, this subject justifiably deserves scrutiny. Several articles have claimed that vasectomy puts men at risk for future development of prostate cancer. We explore articles that have shown the contrary (no link), explore the studies’ strengths and weaknesses, describe possible prostate cancer pathophysiologic mechanisms, and apply Bradford Hill criteria to help discern correlation with causation. The risk and interest of association of prostate cancer with vasectomy has waxed and waned over the last three decades. Based on our review, vasectomy remains a safe form of sterilization and does not increase prostate cancer risk.

The human epididymis: its function in sperm maturation

BACKGROUND

Spermatozoa acquire their fertilizing ability and forward motility properties during epididymal transit. Our knowledge of gamete physiology is based on studies conducted in laboratory and domestic species; our knowledge of these processes in humans is limited. Medical indications for assisted reproductive technologies (ART) have progressed to include male infertility. Surgical procedures allow collection of spermatozoa from all along the human excurrent ducts, and the former have been used with some success in reproductive medicine. This has raised questions over the role of the epididymis in human sperm physiology.

OBJECTIVE AND RATIONALE

To reanalyze what we now know about epididymal physiology in humans and to assess the relevance of laboratory animal models for understanding human physiology and the pathophysiology of the epididymis.

SEARCH METHODS

A systematic bibliographic search of PubMed for articles published in English before May 2015 was carried out using the search terms 'epididymis' and 'sperm maturation'. Literature on the consequences of vasectomy on the epididymis was also searched.

OUTCOMES

Whereas the proximal epididymis is almost exclusively occupied by efferent ducts, the sperm reservoir capacity is poorly developed in humans. At the molecular level, the human transcriptome and proteome show some segment specificity; conflicting results persist with regard to secretome variation along the tubule. The number of genes regulated along the excurrent ducts in men is lower when compared to rodent species, but remains significant. It is challenging to reconcile biochemical and physiological studies with clinical data obtained from men undergoing reanastomosis of the vas deferens at different points along the excurrent duct. We propose that vasectomy/vasovasostomy is a model to understand the consequences of obstruction on epididymis function in humans.

WIDER IMPLICATIONS

Despite the scarcity of biological material available, the interspecies variability of the male reproductive tract urges us to use modern molecular and cellular biology tools to better understand human epididymis physiology in order to apply ART in a more responsible manner.

Vasectomy and the risk of prostate cancer: a meta-analysis of cohort studies

BACKGROUND

The relationship of vasectomy to prostate cancer has great public health significance. However, the results of observational studies were conflicting. To determine whether vasectomy is associated with the risk of prostate cancer, we performed a meta-analysis of cohort studies.

METHODS

A literature search was carried out using Pubmed, Embase, Cochrane Libraryl, and China National Knowledge Infrastructure (CNKI) between January 1966 and July 2013. Before meta-analysis, between-study heterogeneity and publication bias were assessed using adequate statistical tests. Fixed-effect and random-effect models were used to estimate summary relative risks (RR) and the corresponding 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression. Subgroup analyses and sensitivity analysis were also performed.

RESULTS

A total of nine cohort studies contributed to the analysis. There was heterogeneity among the studies but no publication bias. Pooled results indicated that vasectomy was not associated with a significant increase of total prostate cancer risk (RR = 1.07, 95% CI [0.79, 1.46]). When stratified the various studies by geographic location, we found a significant association between vasectomy and increased PCa risk among studies conducted in the USA (RR = 1.54, 95% CI [1.23, 1.93]), however, there was no significant association between vasectomy and PCa risk among studies conducted in non-USA countries (RR = 0.74, 95% CI [0.50, 1.09]). Furthermore, sensitivity analysis confirmed the stability of the results.

CONCLUSIONS

In conclusion, the present meta-analysis of cohort studies suggested that vasectomy was not associated with increased risk of prostate cancer. More in-depth studies are warranted to report more detailed results, including stratified results by age at vasectomy, tumor grade, and tumor stage.

Vasectomy and prostate cancer risk: a meta-analysis of cohort studies

Some studies have suggested that vasectomy is associated with the increased risk of prostate cancer, however, this conclusion is not supported by all the published studies. In order to examine the relationship between vasectomy and prostate cancer risk, we conducted a meta-analysis of cohort studies to clarify this controversial association. PubMed and Medline were used to identify the cohort studies that reported the association of vasectomy with prostate cancer risk from 1980 to January 2015. Based on a random effects model, the RR and 95% CI were used to assess the combined risk. In total, 10 cohort studies involving more than 7027 cases and 429914 participants were included. There was no significant relationship between vasectomy and prostate cancer risk, the pooled RR (95%CI) was 1.11[0.98, 1.27] (P = 0.109). In subgroup-analysis, the relationship between vasectomy and prostate cancer risk was not significantly modified by the length of follow-up and population distribution except Americans. Omission of any single study had little effect on the pooled risk estimate. Little evidence of publication bias was found. In conclusion, our meta-analysis suggests that vasectomy is not associated with the increased risk of prostate cancer. More studies based on other populations including the Chinese are needed.

Update on vasectomy protocol

Vasectomy is a commonly practiced form of male contraception with over half a million procedures performed annually. Among urologists who perform the procedure, there is considerable variation in pre-procedure patient counseling, vasectomy technique, and post-procedure practices regarding confirmation of sterility. We report an overview of the vasectomy literature published within the past year with a focus on guidelines that have been recently published by two major organizations, the American Urological Association (AUA) and the European Association of Urology (EAU).

Vasectomy: AUA guideline

PURPOSE

The purpose of this guideline is to provide guidance to clinicians who offer vasectomy services.

MATERIALS AND METHODS

A systematic review of the literature using the search dates January 1949-August 2011 was conducted to identify peer-reviewed publications relevant to vasectomy. The search identified almost 2,000 titles and abstracts. Application of inclusion/exclusion criteria yielded an evidence base of 275 articles. Evidence-based practices for vasectomy were defined when evidence was available. When evidence was insufficient or absent, expert opinion-based practices were defined by Panel consensus. The Panel sought to define the minimum and necessary concepts for pre-vasectomy counseling; optimum methods for anesthesia, vas isolation, vas occlusion and post-vasectomy follow up; and rates of complications of vasectomy. This guideline was peer reviewed by 55 independent experts during the guideline development process.

RESULTS

Vas isolation should be performed using a minimally-invasive vasectomy technique such as the no-scalpel vasectomy technique. Vas occlusion should be performed by any one of four techniques that are associated with occlusive failure rates consistently below 1%. These are mucosal cautery of both ends of the divided vas without ligation or clips (1) with or (2) without fascial interposition; (3) open testicular end of the divided vas with MC of abdominal end with FI and without ligation or clips; and (4) non-divisional extended electrocautery. Patients may stop using other methods of contraception when one uncentrifuged fresh semen specimen shows azoospermia or ≤ 100,000 non-motile sperm/mL.

CONCLUSIONS

Vasectomy should be considered for permanent contraception much more frequently than is the current practice in the U.S. and many other nations. The full text of this guideline is available to the public at http://www.auanet.org/content/media/vasectomy.pdf.

Putative health risks associated with vasectomy

Vasectomy is widely regarded as a safe method of contraception, but over the years there have been many reports suggesting putative health risks associated with the procedure. Concerns over the possible association of vasectomy with a number of medical conditions, including cardiovascular disease, testicular cancer, prostate cancer, psychologic distress, and a variety of immune complex-mediated disease processes have been reported. Most recently, a manuscript from the neurology literature has described an association between vasectomy and primary progressive aphasia, a rare variety of frontotemporal dementia. This article reviews the literature surrounding each of these purported health concerns. Because the ultimate findings have important ramifications for both informed consent of vasectomy patients and for public health, the reported health risks in question should be critically evaluated.

Sterilization in the United States

Unintended pregnancies are expensive for patients and for society in terms of medical costs, the cost of caring for more children, and the cost to personal and professional goals. Sterilization is the most common contraceptive method utilized by couples in the United States. Given technological advances over the past few decades, male and female surgical sterilization has become a safe, convenient, easy, and highly effective birth control method for the long term. This article reviews current male and female sterilization options.

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.

Canadian Contraception Consensus

This document has been archived because it contains outdated information. It should not be consulted for clinical use, but for historical research only. Please visit the journal website for the most recent guidelines.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

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 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.

Use of large medical databases to study associations between diseases

We describe the use of a dataset of statistical medical records, the Oxford Record Linkage Study (ORLS), to identify diseases which occur together more commonly (association), or less commonly (dissociation), than their individual frequencies in the population would predict. We investigated some conditions known or suspected to enhance the subsequent risk of cancer, some conditions thought to be linked with schizophrenia, and some associations between conditions with a known autoimmune component. Diseases may occur in combination more often (or less often) than expected by chance because one predisposes to (or protects against) another or because they share environmental and/or genetic mechanisms in common. The investigation of such associations can yield important information for clinicians interested in potential disease sequelae, for epidemiologists trying to understand disease aetiology, and for geneticists attempting to determine the genetic basis of variation in disease course among individuals. We suggest that, through the use of datasets like the ORLS, it will be possible to 'map' comprehensively the phenomic expression of co-occurring diseases.

Safety and effectiveness of vasectomy

OBJECTIVE

To recommend further research on vasectomy based on a systematic review of the effectiveness and safety of vasectomy.

DESIGN

A systematic MEDLINE review of the literature on the safety and effectiveness of vasectomy between 1964 and 1998.

MAIN OUTCOME MEASURE(S)

Early failure rates are <1%; however, effectiveness and complications vary with experience of surgeons and surgical technique. Early complications, including hematoma, infection, sperm granulomas, epididymitis-orchitis, and congestive epididymitis, occur in 1%-6% of men undergoing vasectomy. Incidence of epididymal pain is poorly documented. Animal and human data indicate that vasectomy does not increase atherosclerosis and that increases in circulating immune complexes after vasectomy are transient in men with vasectomies. The weight of the evidence regarding prostate and testicular cancer suggests that men with vasectomy are not at increased risk of these cancers.

CONCLUSION(S)

Publications to date continue to support the conclusion that vasectomy is a highly effective form of contraception. Future studies should include evaluations of the long-term effectiveness of vasectomy, evaluating criteria for postvasectomy discontinuation of alternative contraception for use in settings where semen analysis is not practical, and characterizing complications including chronic epididymal pain syndrome.

Sterilization and its consequences

The purpose of this review is to analyze critically the two techniques of sterilization (bilateral tubal ligation [BTL] and vasectomy) so that a physician may provide informed consent about methods of sterilization. A MEDLINE search and extensive review of published literature dating back to 1966 was undertaken to compare preoperative counseling, operative procedures, postoperative complications, procedure-related costs, psychosocial consequences, and feasibility of reversal between BTL and a vasectomy. Compared with a vasectomy, BTL is 20 times more likely to have major complications, 10 to 37 times more likely to fail, and cost three times as much. Moreover, the procedure-related mortality, although rare, is 12 times higher with sterilization of the woman than of the man. Despite these advantages, 300,000 more BTLs were done in 1987 than vasectomies. In 1987, there were 976,000 sterilizations (65 percent BTLs and 35 percent vasectomies) with an overall cost of $1.8 billion. Over $260 million could have been saved if equal numbers of vasectomies and BTLs had been performed, or more than $800 million if 80 percent had been vasectomies, as was the case in 1971. The safest, most efficacious, and least expensive method of sterilization is vasectomy. For these reasons, physicians should recommend vasectomy when providing counseling on sterilization, despite the popularity of BTL.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to predict the failure rates and likelihood of successful reversal of tubal ligation and vasectomy; to recall the difference in cost between the two sterilization procedures, and to describe the short-term and long-term complications associated with each of the two methods of sterilization.

The association between vasectomy and prostate cancer: a systematic review of the literature

OBJECTIVE

To evaluate the possible association between vasectomy and prostate cancer.

DESIGN

Systematic review of the literature.

PATIENT(S)

Fourteen original studies published between January 1985 and December 1996 that addressed the association between vasectomy and prostate cancer.

MAIN OUTCOME MEASURE(S)

The strength of the association was estimated with the use of a meta-analysis (DerSimonian and Laird method). A sensitivity analysis was conducted to assess the impact of different sources of heterogeneity.

RESULT(S)

Fourteen original papers were reviewed (5 cohort and 9 case-control studies). Relative risks ranged between 0.44 (95% confidence interval [CI] = 0.1-4.0) and 6.70 (95% CI = 2.1-21.6). The overall relative risk (DerSimonian and Laird estimate) was 1.23 (95% CI = 1.01-1.49). The sensitivity analysis showed that this measure was very sensitive to the study base, the type of design used, and the possibility of bias. Further, the funnel plot demonstrated the probable existence of publication bias.

CONCLUSION(S)

No causal association was found between vasectomy and prostate cancer. Individuals who have undergone vasectomy are not at high risk for the development of prostate cancer.

The Quality of Surgical Care Project: a model to evaluate surgical outcomes in Western Australia using population-based record linkage

BACKGROUND

The aim of this study is to establish a model to evaluate surgical outcomes and, where indicated, recommend changes to improve the quality of surgical care in Western Australia (WA). Open resection for aneurysm of the abdominal aorta was the first procedure evaluated and the results are reported in an accompanying paper.

METHODS

The Quality of Surgical Care Project (QSCP) is conducted under the aegis of the Royal Australasian College of Surgeons (RACS) in WA, and brings together a multidisciplinary team of surgeons, public health researchers and health service administrators. The Western Australia Health Services Research Linked Database (the WA Linked Database) is used to provide linked chains of patients records residing in the state health department from the following sources: hospital morbidity data system, birth and death records, mental health services data, cancer registrations and midwives' notifications. This links 16 years of population-based patient records from 1980, including all public and private hospital admissions and re-admissions. The Quality of Surgical Care Project was established to use and to correlate the data from the WA Linked Database.

RESULTS

The result is a powerful database for a contained population that is available for scientific analysis by a multidisciplinary team of clinical epidemiologists, surgeons and health service managers. Users will have the ability to establish benchmark standards for the outcomes of surgical procedures in WA for use in quality improvement programmes run by the College and will facilitate self-directed performance auditing activities as a commitment to greater community accountability.

CONCLUSIONS

The Quality of Surgical Care Project provides a potential model of benefits to be realized by both the medical profession and the community through multidisciplinary collaboration supported by adequate information. Although migration from WA is relatively low, future linkage to the state electoral roll will allow correction for any population change.

Is vasectomy harmful to health?

Since the late 1960s, vasectomy has been a popular and widely used form of contraceptive in Britain for couples who do not want to have any more children. However, throughout the past decade there has been considerable concern about the safety of this procedure. This paper reviews the current opinion on the possible health considerations associated with this operation and shows that the latest news is mostly reassuring.

A case-control study of cancer of the prostate in Somerset and east Devon

A case-control study in Somerset and east Devon was undertaken to investigate possible risk factors for prostatic cancer. A total of 159 cases, diagnosed at Taunton. Yeovil and Exeter hospitals between May 1989 and May 1991, were identified prospectively and interviewed with a structured questionnaire. A total of 161 men diagnosed with benign prostatic hypertrophy and 164 non-urological hospital controls were given identical questionnaires. The questionnaire covered a wide range of factors identified from previous studies, but the central hypotheses for this study related to diet (fat and green vegetables), sexual activity and farming as an occupation. This study found no association between farming and risk of prostatic cancer (odds ratio = 0.74, 95% confidence interval 0.46-1.18), nor with sexual activity as measured by number of sexual partners (chi-squared test for trend P = 0.52). A history of sexually transmitted disease was not significantly associated with prostatic cancer, but the numbers involved were very small and the odds ratio of 2.06 (0.38-11.2) is consistent with the hypothesis. A range of questions aimed at eliciting dietary fat intake produced no significant associations, although meat consumption showed increasing risk with increasing consumption (test for trend P = 0.005). Increased consumption of leafy green vegetables was associated with lower risk, but not significantly so (test for trend P = 0.16). As expected with so many factors investigated, some statistically significant associations were found, although these can only be viewed as hypothesis generating in this context. These included apparent protective effects of circumcision and high fish consumption.

How is individual risk for prostate cancer assessed?

A man's risk of developing prostate cancer is influenced by both genetic and nongenetic factors. Genetic factors are particularly important at younger ages, and the attributable risk of strong genetic factors could be as high as 43% among men less than 55 years of age; however, only about 9% of all cases may be directly attributable to a family history of prostate cancer. Race appears to be an important determinant of risk; African-American men are at high risk, whereas men of oriental ancestry are at lower risk. The bases of these racial differences remain obscure but may be related to hormonal differences. Modifiable risk factors are most important from a public health perspective. Diet or closely related factors appear to hold the most promise for prevention, although the precise factors are unknown. The strongest evidence indicates that some component of animal fat intake appears to act as a promoter of prostate cancer. Other dietary factors, including vitamin D, vitamin E, and beta-carotene and lycopene, may confer protection, but these require more study. Many but not all studies that have examined long-term effects of vasectomy suggest that this procedure may increase risk of prostate cancer, but whether this association is causal is not established. Occupational factors, smoking, and physical activity level do not appear to be major determinants of prostate cancer risk.

Male contraception

With the powerful tools of molecular investigation, the last decade has witnessed the most remarkable scientific advance in our history, yet no new leads for male contraception have been forthcoming. All the likely methods of male contraception discussed above were derived from relatively 'old' physiological principles or serendipitous observations. The increasing gap between fundamental research (in the control of mammalian spermatogenesis) and the lack of clinical application are a testament to the low public funding priority afforded to male reproduction and the unwillingness of the pharmaceutical industry to invest in male reproductive research and development. Yet amidst such an unfavourable setting and with very limited support, it is heartening to note that the prospects of introducing a new systemic method for male contraception into the market by the end of this millenium has been greatly enhanced. Thus the results of recent studies have confirmed the contraceptive efficacy of sex steroid-induced oligozoospermia and unexpectedly revealed an ethnically distinct pattern of susceptibility to the hormonal suppression of spermatogenesis. Thus, Asian men are more responsive than are caucasian, and long-acting testosterone esters now being tested in that most densely populated part of the world may well hasten the large-scale application of this method. This is probably the most effective way to correct the misconceptions that men are unwilling or disinterested in sharing in family planning options with their partners. Together with the increased acceptance of novel non-surgical and reversible methods of vas deferens occlusion and the availability of improved non-latex condoms, the currently unfulfilled contraceptive needs of millions of men can be increasingly met in future years. The consequent increase in overall contraceptive prevalence could well make the telling difference between demographic catastrophe and maintaining good quality existence. Politicians, scientists and industrialists need to wake up to their responsibilities and the opportunities offered by this untapped resource and market potential.

The epidemiology of non-seminomatous germ cell tumours in the west of Scotland 1975-89

A total of 438 males resident in the six West of Scotland Health Board areas were notified to the cancer registry with a diagnosis of teratoma between 1 January 1975 and 31 December 1989. Non-registration was between 2% and 3.4%; a further 44 cases were ascertained through independent listings in the major tertiary referral centres. There were four (1%) duplicate registrations and 16 (4%) were incorrect on the basis of pathology (three) or residence (13). Of these, most (26) were registered with alternative diagnoses and eight were registered on the pre-1985 manual system. The positive correlation between socioeconomic status and incidence was confirmed by linking residential postcode at diagnosis to the Carstairs and Morris Deprivation Index. There was an increasing incidence, both overall and for men aged 15-44 years, with doubling times of 20 and 25 years respectively. The increase was confined to men resident in the more deprived postcode sectors; the incidence rate among men from the most affluent areas remained unchanged throughout the period of study.

[Formation of a cohort of opiate addicts through linkage of confidential records]

The need to combine several files in order to create a cohort of opiate addicts, sufficiently large for the analysis of its mortality, requires use of the probabilistic method of record linkage. This study is a preliminary phase in which two sub-files of the Hospital del Mar (Barcelona) Register of toxicological emergencies are linked. This phase served to adapt probabilistic record linkage to our files, develop computer programs, define agreement criteria, and evaluate the validity and performance of the method. In order to safeguard confidentiality, identification variables were limited to sex, birth date and three initial letters from each surname. The automated probabilistic linkage was seen to be feasible, valid and efficient; in contrast to deterministic approaches, sensitivities and specificities above 95% were obtained with visual reviewing of under 5% of the records. Difficulties encountered during the process are discussed.

Risk of testicular cancer after vasectomy: cohort study of over 73,000 men

OBJECTIVE

To confirm or refute reports that vasectomy may increase the risk of cancers of the testis and prostate.

DESIGN

Computerised record linkage study of cohort of men with vasectomy and comparison of cancer rates with those in the whole Danish population; manual check of all records of patients with testicular and prostate cancer diagnosed within the first year of follow up.

SETTING

Denmark 1977-89.

SUBJECTS

Cohort of 73,917 men identified in hospital discharge and pathology registers as having had a vasectomy for any reason during 1977-89.

MAIN OUTCOME MEASURES

Observed incidences of testicular, prostate, and other cancers up to the end of 1989.

RESULTS

The overall pattern of cancer incidence in the study cohort was similar to that expected nationally. No increased incidence in testicular cancer was observed (70 cases; standardised morbidity ratio 1.01 (95% confidence interval 0.79 to 1.28)). The incidence during the first year of follow up was also close to that expected (nine cases; standardised morbidity ratio 0.80 (0.36 to 1.51)). The incidence of prostate cancer was not increased (165 cases; standardised morbidity ratio 0.98 (0.84 to 1.14)).

CONCLUSIONS

The incidence of testicular cancer in men with vasectomy is no higher than in other men. Vasectomy does not cause testicular cancer and does not accelerate the growth or diagnosis of pre-existing testicular neoplasms. Data concerning a causal relation between vasectomy and prostate cancer were inconclusive.

Vasectomy and vasectomy reversal

Vasectomy remains the safest method of birth control and there is much to commend it in the setting of a stable family relationship. However, some aspects of this operation have been wrongly presented in an attempt to widen its popularity and increase public acceptance. A simple procedure it may be but it is not totally free of complications; sometimes the operation has to be repeated and rarely it may reverse spontaneously even after the most stringent precautions. The family planning officer who counsels a prospective candidate and the surgeon who undertakes the procedure must ensure that these facts are understood by the patient with crystal clarity and that this fact is duly recorded on a signed and witnessed permission slip. Any organization which includes vasectomy in its programme of family planning should include advice and referral for vasectomy reversal in exactly the same way that the pill may be stopped or a coil can be removed. Fertility can be successfully restored by vasovasostomy in 50% of men who wish to have their vasectomies reversed, which often is due to a change in circumstances beyond their direct control.

Vasectomy and prostate cancer

Numerous epidemiologic studies of vasectomized men have been conducted over the last decade. The majority of the reports have been reassuring with regard to possible long-term health consequences following male sterilization. In February 1993, two articles suggesting a relationship between vasectomy and prostate cancer appeared in the literature. Following publication of these studies, the United States National Institutes of Health (NIH) organized a meeting of experts to review the most recent literature on vasectomy and prostate cancer. After considering the evidence from the aforementioned studies and the preliminary findings of three unpublished studies, the NIH panel concluded that there was insufficient evidence of a real association between vasectomy and prostate cancer. This article reviews current information concerning the relationship, and recommends that providers continue to provide vasectomy as a contraceptive option. The research community should continue to investigate the possibility of a relationship between vasectomy and prostate cancer.