Are men who have vasectomies at a greater risk for testicular cancer than those who don’t.

Annotated Bibliographies: Are Men Who Undergo Vasectomy is at Increased Risk of Developing Testicular Cancer?
Background
Vasectomy is the surgical process of male sterilization or permanent contraception. The procedure involves surgical incision of the vas deferens in the testis and ligating the same in such a way, so the sperm is prevented from entering into the semen. Unavailability of sperm in the semen will not cause any pregnancy risk in his female sexual partner because fertilization of ovum is only possible upon fusion with the sperm. The operative procedure takes nearly 30 minutes and may be performed in a physician’s chamber, without the need for hospital admission. Evidence suggests that pregnancy occurs in 0.07% of women whose male sexual partners underwent vasectomy6.
The procedure is normally very safe and effective; however, vasectomy failure may occur in 1-2% cases. The common complications of vasectomy include genito-urinary infection, haematoma, traumatic fistulae, post vasectomy pain, psychological effects and primary progressive aphasia9. The sperm gets deposited within the testis and gives rise to anti-sperm antibodies that cause deposition of immune-complexes6. However, such deposition of immune complexes does not increase the risk of atherosclerosis or heart disease.
On the other hand risk of testicular cancer and prostate cancer are evaluated in various studies and reports suggest that vasectomy does not impose the additional risk of testicular or prostate cancer.

This article will evaluate the notion that “Men Who Undergo Vasectomy is at Increased Risk of Developing Testicular Cancer”. An Annotated Bibliographic approach will be adopted for evaluating the hypothesis. The search strategies involved keywords like “testicular cancer”, “vasectomy”, “risks”, “long term study” in various clinical databases and journals.
Annotated Bibliographies
Study 1
Aware N, Krishnan J, Boustead G, Hanbury D, McNicholas T. Complications of Vasectomy. Ann R Coll Surg Engl. 2005; 87: 406–410.doi:  10.1308/ 003588405X71054
The authors reported a meta-analysis of various studies through internet search based on evidence-based websites. The complications of vasectomy that were reported included genito-urinary infection, haematoma, traumatic fistulae, post vasectomy pain, psychological effects, dementia, trauma, deposition of immune complexes comprised of sperm and anti-sperm antibodies in testis. They further concluded that vasectomy does not lead to either testicular or prostate cancer. On the other hand, vasectomy is related to lower mortality compared to tubular occlusion1.
Since, the study was a meta-analysis and included various scholarly articles reviewing the effects of vasectomy on testicular cancer; it is a reliable evidence to conclude that vasectomy does not increase the risk of testicular function in individuals. This is the most robust study that helps us to confirm that testicular cancer is neither caused by vasectomy or prostatectomy since it is a meta-analysis and includes nearly all reports conducted on vasectomy and testicular cancer. Although the study satisfies there is no need to worry regarding testicular cancer or prostate cancer in association to vasectomy, the study failed to analyze the data after controlling and standardizing for ethnicity, nationality and pre-cancerous/non-cancerous state of the individuals.
Study 2
Cale AR, Farouk M, Prescott RJ, Wallace IW. Does vasectomy accelerate testicular tumour? The importance of testicular examinations before and after vasectomy. BMJ.1990; 10;300(6721):370–370.Doi:10.1007/978-2-8178-0346-3_9
The study was done by the authors to address the factors that caused an increase in testicular cancer in Scottish men. During 1977 to 1987, 3079 individuals attended the only hospital at West Lothian District for a vasectomy. * Individuals amongst them suffered from the testicular tumour within an average of 1.9 years (0.25 years to 4 years) of vasectomy. The authors suggested that vasectomy accelerated the development of a palpable tumour from a carcinoma in situ, and they concluded that palpable tumours are overlooked at the time of vasectomy. They concluded there should be a thorough screening of an individual for palpable tumours or presence of carcinomas through cytological examination of semen, before undertaking a vasectomy in such individuals. However, the authors also suggested that large prospective studies and co-morbid factors like smoking and socio-economic status of individuals must be included in the future analysis, to recommend that vasectomy increases the risk of testicular cancer in Scottish men2.
The study reflected that it would be wise to evaluate the risk-benefits ratio of performing a vasectomy on individuals who already present with palpable tumours or presence of carcinomas. This is because vasectomy may aggravate testicular cancer that is already present before the vasectomy. Individuals who are detected with palpable tumours or testicular cancer should not be encouraged to undergo a vasectomy until otherwise stated. Since the study portrays that palpable tumours and precancerous state are responsible for cancer in the vasectomised individual, such evidence need to substantiated by designing a control arm with the same category of palpable tumours or same pre-cancerous state to nullify the assumptions that vasectomy do not add to the risk of testicular carcinoma.
Study 3
Jorgensson , M, Giwercman, A, & Skakkabaek. (1993)Testicular cancer after vasectomy: Origin from carcinoma in situ of the testis. European Journal of Cancer. 29(7),1062-1064
The study evaluated the hypothesis whether vasectomy increases the chance of germinal testicular cancer. Carcinoma in situ (CIS) of the testis is a pre-invasive lesion which occurs before germinal testicular cancer. CIS is found adjacent to a germinal testicular cancer. CIS is a malignant gonocyte formed during embryogenesis. The authors concluded from the study of testicular tissue in 5 vasectomised patients with testicular cancer that CIS occurs in adjacent tissues of cancer and epididymis. They concluded testicular cancer after vasectomy is caused due to the presence of CIS. However, testicular cancer does not originate from vasectomy3.
The study was again endorsed that testicular cancer is not associated with vasectomy procedure; however, the study did not confirm whether vasectomy precipitates the development of testicular cancer from pre-invasive CIS lesions.
Study 4
Hewitt G, Logan C, Curry R. Does vasectomy cause testicular cancer? BMJ Clinical Research.1990; 300(6729):944-5. doi/10.1111/j.1464-410X.1993.tb16034.x
In this study 330 men who developed testicular cancers in Northern Ireland between1975 to 1990 were interviewed. Their particulars were cross-matched with a sample of 2904 men who underwent vasectomy during the period 1970 and 1985. The expected number of testicular cancer from our assumption was 2. However, only one person reported testicular cancer. The authors concluded that vasectomy did not increase the risk of testicular cancer4.
The above study indicates that risk of the testicular function is rather half compared to all causes of testicular cancer. Hence, it can be speculated that vasectomy does not adds to the risk of testicular cancer and other factors, apart from vasectomy, have a greater risk of causing testicular cancer. The article is helpful in the sense it provides an opportunity to evaluate the comorbid risk factors for testicular cancer either alone or in association to vasectomy. Although the study suggested that risk of testicular cancer is half in patients undergoing a vasectomy, the controls (who did not undergo vasectomy) must be standardized for smoking and other factors.
Study 5
Moller H, Knudsen, L, Lynge E. Risk of Testicular Cancer after Vasectomy: Cohort study
over 73000 men. BMJ. 1994; 309:295.doi: 10.1111/j.1464-410X.2009.08854.x
The study was done through computerized record linkage of individuals belonging to Danish population who underwent vasectomy during the period 1977 to 1989. A cohort of 73197 individuals was recognized through hospital discharges and pathology registers. The overall incidence of testicular, prostate and other cancers was similar to the nationally expected cancer risk for Danish men who did not undergo a vasectomy. Further, the study elucidated that there was no increased incidence of testicular cancer (standard morbidity ratio 1.01 with a confidence interval of 0.79 to 1.28). Even the risk of prostate cancer was not increased (standardised morbidity ratio was 0.98 with 955 confidence interval as 0.84 to 1.14). The conclusion from the study revealed that vasectomy does not cause testicular or prostate cancer and also does not accelerate the growth or diagnosis of pre-existing testicular neoplasms5.
From the above study, it becomes evident that the lower limit of confidence interval was as low as 0.79 which indicates that vasectomy does not increase the chances of testicular cancer and hence vasectomy is a safe procedure because it also does not accelerates or potentiates the growth of testicular neoplasms. This article is helpful in ensuring the safety apprehensions of vasectomy in patients and physicians. However, it should be noted that such conclusion was drawn from the Danish population, and chances for population bias cannot be ruled out. The same protocol may be carried out in multi-centric and multinational settings to substantiate the claims of the study.
Study 6
Rosenberg, L, Palmer, J,Zauber,A,Warshauer,M,Strom,B,Harlap,S & Shapiro,S. (1994). The Relation of Vasectomy to the Risk of Cancer. Am. J. Epidemiol.  140 (5):431-438
The authors reassessed the risk of testicular cancer, prostate cancer, and lung cancer after vasectomy from a surveillance study during 1988 to 1992. The relative risk of testicular cancer was 0.8 (with 95% confidence interval of 0.4 to 1.9). They confirmed that there is little support to prove that vasectomy is associated with the risk of prostate cancer or other cancers (including testicular cancer)6.
The study again assures to find any cause-and-effect relationship between vasectomy and testicular cancer. However, the authors stated that higher relative risks indicated in some cancers may happen due to an upward bias. Similarly, it might be possible that lower relative risks reported ( for example in testicular cancer) may have happened from downward bias.
Study 7
Strader CH, Weiss NS, Darling JR. Vasectomy and the risk of testicular cancer. Am J Epidemiol. 1988; 128(1):56-63.doi:10.2165/00115677-199804020-00001
In this study, 333 adult males belonging to 13 counties of western Washington State who was suffering from testicular cancer during 1977 to 1983 were interviewed by telephone regarding their genital tract conditions that included the history of vasectomy. Further, 729 individuals belonging to the same population were interviewed randomly over the telephone. A higher proportion of testicular cancer was reported in patients who underwent vasectomy compared to controls (relative risk 1.5 with a 955 confidence interval of 1 to 2.2). The testicular cancer was only reported by Catholic men; however the proportion of vasectomy was equal between Catholics and non-Catholics compared to controls. The authors concluded that such difference might have been due to underreporting of testicular cancer in Catholic individuals considered as controls10.
The above study clearly portrays that if the proportion of vasectomy is equal in catholic and non-catholic individuals, reporting of testicular cancer should have been in the similar proportion. However, such was not the case, and only Catholic men reported testicular cancer. Therefore, socio-economic status, food habits and other variables like smoking should be standardized to conclude that vasectomy causes testicular cancer. This article is helpful to identify in further research the risk of testicular cancer in specific ethnic groups, and if vasectomy is found to be the confirmed cause, it should not be performed on that specific population and they should be encouraged for other contraceptive measures for family planning. Apart from that the study was done through the telephonic interview and no real evidence of either suffering from cancer or not suffering from cancer were not validated, which jeopardizes the claim of the study. In future medical documentation must be verified before categorizing individuals as cancerous or noncancerous.
Study 8
Thornhill JA, Butler M, Fitzpatrick JM. Could vasectomy accelerate testicular cancer? The importance of pre-vasectomy examination. Br J Urol. 1987; 59: 367.doi: 10.1111/j.1464-410X.1987.tb04660.x
The authors in this study suggested that increased incidence of testicular cancer does occur in individuals. However, they also concluded that testicular cancers might have been already present in that individual before the person underwent a vasectomy. They could not conclude on a definitive note that vasectomy is the cause of testicular cancer. The authors also concluded the period of detection of testicular cancers were very short and immediately after vasectomy, the relation of vasectomy to testicular cancer is unlikely8.
The study clearly states that cancer of the testis cannot develop in a short period of one to two years after vasectomy is done. Therefore, as the previous study left some doubt that vasectomy aggravates testicular cancer, this study negated such assumptions8. The study is helpful because the earlier apprehensions of vasectomy associated with testicular function can be forsaken. The authors just made an assumption that testicular cancers may have been present in which cancer developed after vasectomy. Once again to prove such claim, future studies must clearly state with evidence whether individuals who underwent vasectomy already had testicular cancers?

Summary
The various studies evaluated through annotated bibliographies reflected that vasectomy is a safe procedure, and apart from minor complications it does not cause or predispose an individual to either testicular or prostate cancer. Such conclusion was drawn from a large database of patients represented in the bibliographies who belonged to different nations, different ethnicity, and different socio-economic status.

Bibliography
Aware N, Krishnan J, Boustead G, Hanbury D, McNicholas T. Complications of Vasectomy. Ann R Coll Surg Engl. 2005; 87: 406–410. doi:  10.1308/ 003588405X71054
Cale AR, Farouk M, Prescott RJ, Wallace IW. Does vasectomy accelerate testicular tumour? Importance of testicular examinations before and after vasectomy. BMJ.1990; 10;300(6721):370–370. Doi:10.1007/978-2-8178-0346-3_9
Jorgensson , M, Giwercman, A, & Skakkabaek. (1993)Testicular cancer after vasectomy: Origin from carcinoma in situ of the testis. European Journal of Cancer. 29(7),1062-1064
Hewitt G, Logan C, Curry R. Does vasectomy cause testicular cancer? BMJ Clinical Research.1990; 300(6729):944-5. doi/10.1111/j.1464-410X.1993.tb16034.x
Moller H, Knudsen, L, Lynge E. Risk of Testicular Cancer after Vasectomy: Cohort study over 73000 men. BMJ. 1994; 309:295.doi: 10.1111/j.1464-410X.2009.08854.x
Moss AR, Osmond D, Bacchetti P, et al. Hormonal risk factors in testicular cancer: a case-control study. Am] Epidemiol 1986;124:39-52. doi:  10.2217/fon.09.116Rosenberg, L, Palmer, J,Zauber,A,Warshauer,M,Strom,B,Harlap,S & Shapiro,S. (1994). The Relation of Vasectomy to the Risk of Cancer. Am. J. Epidemiol.  140 (5):431-438.
Strader CH, Weiss NS, Darling JR. Vasectomy and the risk of testicular cancer. Am J Epidemiol. 1988; 128(1):56-63. doi:10.2165/00115677-199804020-00001
Schwingl, Pamela J; Guess, Harry A (2000). “Safety and effectiveness of vasectomy”. Fertility and Sterility 73 (5): 923–936.doi:10.1016/S0015-0282(00)00482-9
Thornhill JA, Butler M, Fitzpatrick JM. Could vasectomy accelerate testicular cancer? The importance of pre-vasectomy examination. Br J Urol. 1987; 59: 367. doi: 10.1111/j.1464-410X.1987.tb04660.x