Cancer risk in first- and second-degree relatives of men with poor semen quality

Describing patterns of familial cancer risk in subfertile men using population pedigree data

STUDY QUESTION

Can we simultaneously assess risk for multiple cancers to identify familial multicancer patterns in families of azoospermic and severely oligozoospermic men?

SUMMARY ANSWER

Distinct familial cancer patterns were observed in the azoospermia and severe oligozoospermia cohorts, suggesting heterogeneity in familial cancer risk by both type of subfertility and within subfertility type.

WHAT IS KNOWN ALREADY

Subfertile men and their relatives show increased risk for certain cancers including testicular, thyroid, and pediatric.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort of subfertile men (N = 786) was identified and matched to fertile population controls (N = 5674). Family members out to third-degree relatives were identified for both subfertile men and fertile population controls (N = 337 754). The study period was 1966-2017. Individuals were censored at death or loss to follow-up, loss to follow-up occurred if they left Utah during the study period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Azoospermic (0 × 106/mL) and severely oligozoospermic (<1.5 × 106/mL) men were identified in the Subfertility Health and Assisted Reproduction and the Environment cohort (SHARE). Subfertile men were age- and sex-matched 5:1 to fertile population controls and family members out to third-degree relatives were identified using the Utah Population Database (UPDB). Cancer diagnoses were identified through the Utah Cancer Registry. Families containing ≥10 members with ≥1 year of follow-up 1966-2017 were included (azoospermic: N = 426 families, 21 361 individuals; oligozoospermic: N = 360 families, 18 818 individuals). Unsupervised clustering based on standardized incidence ratios for 34 cancer phenotypes in the families was used to identify familial multicancer patterns; azoospermia and severe oligospermia families were assessed separately.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to control families, significant increases in cancer risks were observed in the azoospermia cohort for five cancer types: bone and joint cancers hazard ratio (HR) = 2.56 (95% CI = 1.48-4.42), soft tissue cancers HR = 1.56 (95% CI = 1.01-2.39), uterine cancers HR = 1.27 (95% CI = 1.03-1.56), Hodgkin lymphomas HR = 1.60 (95% CI = 1.07-2.39), and thyroid cancer HR = 1.54 (95% CI = 1.21-1.97). Among severe oligozoospermia families, increased risk was seen for three cancer types: colon cancer HR = 1.16 (95% CI = 1.01-1.32), bone and joint cancers HR = 2.43 (95% CI = 1.30-4.54), and testis cancer HR = 2.34 (95% CI = 1.60-3.42) along with a significant decrease in esophageal cancer risk HR = 0.39 (95% CI = 0.16-0.97). Thirteen clusters of familial multicancer patterns were identified in families of azoospermic men, 66% of families in the azoospermia cohort showed population-level cancer risks, however, the remaining 12 clusters showed elevated risk for 2-7 cancer types. Several of the clusters with elevated cancer risks also showed increased odds of cancer diagnoses at young ages with six clusters showing increased odds of adolescent and young adult (AYA) diagnosis [odds ratio (OR) = 1.96-2.88] and two clusters showing increased odds of pediatric cancer diagnosis (OR = 3.64-12.63). Within the severe oligozoospermia cohort, 12 distinct familial multicancer clusters were identified. All 12 clusters showed elevated risk for 1-3 cancer types. An increase in odds of cancer diagnoses at young ages was also seen in five of the severe oligozoospermia familial multicancer clusters, three clusters showed increased odds of AYA diagnosis (OR = 2.19-2.78) with an additional two clusters showing increased odds of a pediatric diagnosis (OR = 3.84-9.32).

LIMITATIONS, REASONS FOR CAUTION

Although this study has many strengths, including population data for family structure, cancer diagnoses and subfertility, there are limitations. First, semen measures are not available for the sample of fertile men. Second, there is no information on medical comorbidities or lifestyle risk factors such as smoking status, BMI, or environmental exposures. Third, all of the subfertile men included in this study were seen at a fertility clinic for evaluation. These men were therefore a subset of the overall population experiencing fertility problems and likely represent those with the socioeconomic means for evaluation by a physician.

WIDER IMPLICATIONS OF THE FINDINGS

This analysis leveraged unique population-level data resources, SHARE and the UPDB, to describe novel multicancer clusters among the families of azoospermic and severely oligozoospermic men. Distinct overall multicancer risk and familial multicancer patterns were observed in the azoospermia and severe oligozoospermia cohorts, suggesting heterogeneity in cancer risk by type of subfertility and within subfertility type. Describing families with similar cancer risk patterns provides a new avenue to increase homogeneity for focused gene discovery and environmental risk factor studies. Such discoveries will lead to more accurate risk predictions and improved counseling for patients and their families.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by GEMS: Genomic approach to connecting Elevated germline Mutation rates with male infertility and Somatic health (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): R01 HD106112). The authors have no conflicts of interest relevant to this work.

TRIAL REGISTRATION NUMBER

N/A.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Reproduction as a window for health in men

Male factor infertility is widely considered a harbinger for a man's general health. Failure of reproduction often accompanies other underlying processes, with growing evidence suggesting that a diagnosis of infertility increases the likelihood of developing future cardiac, metabolic, and oncologic diseases. The goal of this review is to provide a comprehensive overview of the research on male fertility as a marker for current and future health. A multidisciplinary approach is essential, and there is growing consensus that the male fertility evaluation offers an opportunity to better men's wellness beyond their immediate reproductive ambitions.

Male Infertility and the Risk of Developing Testicular Cancer: A Critical Contemporary Literature Review

Background and Objectives: The relationship between male infertility (MI) and testicular cancer (TC) is bilateral. On one hand, it is well-established that patients diagnosed with TC have a high risk of pre- and post-treatment infertility. On the other hand, the risk of developing TC in male infertile patients is not clearly defined. The objective of this review is to analyze the histopathological, etiological, and epidemiological associations between MI and the risk of developing testicular cancer. This review aims to provide further insights and offer a guide for assessing the risk factors for TC in infertile men. Materials and Methods: A comprehensive literature search was conducted to identify relevant studies discussing the relationship between MI and the risk of developing TC. Results: The incidence rates of germ cell neoplasia in situ (GCNIS) appear to be high in infertile men, particularly in those with low sperm counts. Most epidemiological studies have found a statistically significant risk of developing TC among infertile men compared to the general or fertile male populations. The concept of Testicular Dysgenesis Syndrome provides an explanatory model for the common etiology of MI, TC, cryptorchidism, and hypospadias. Clinical findings such as a history of cryptorchidism could increase the risk of developing TC in infertile men. Scrotal ultrasound evaluation for testis lesions and microlithiasis is important in infertile men. Sperm analysis parameters can be useful in assessing the risk of TC among infertile men. In the future, sperm and serum microRNAs (miRNAs) may be utilized for the non-invasive early diagnosis of TC and GCNIS in infertile men. Conclusions: MI is indeed a risk factor for developing testicular cancer, as demonstrated by various studies. All infertile men should undergo a risk assessment using clinical examination, ultrasound, and semen parameters to evaluate their risk of TC.

Seasonal variation in semen quality is not associated with fecundity in the Utah Population Database

We determine whether a suspected seasonal variability in semen quality affect subsequent live birth rates. This is a retrospective, cohort analysis of men who provided semen analyses as part of fertility workup through a large andrology lab between 1996 and 2013 and corresponding birth rates using the Utah Population Database (UPDB). Semen parameters were analysed including total motile count (TMC), total sperm count, sperm concentration and progressive motility. Corresponding live births reflect those born in the state of Utah and were derived from birth certificate data available in the UPDB. Descriptive statistics were reported along with linear regression analysis with mixed effected models to test for an interaction between seasonal variation in semen quality and birth rates, accounting for age at the time of the semen analysis and abstinence time. A total of 11,929 patients and 14,765 semen samples were included. Only 3597 men (39% of men) had one or more values outside the World Health Organization reference range for their semen parameters. Linear regression demonstrated a consistent U-shaped relationship between TMC, total sperm count, and sperm concentration and season, with spring and winter yielding the highest values with a decline in the summer and fall. 7319 of these males had recorded live births for a total of 13,502 live births during the study period after a median follow-up of 7.2 years (IQR: 3.9-11.0). We did not find a significant interaction between specific semen parameters for a specific season and subsequent live births. Semen quality was the highest in the spring and winter, however there was no interaction between seasonal variability in semen quality and subsequent births. This is one of the largest studies describing seasonal variation in semen quality in humans.

Lower female partner live birth rate in male cancer survivors: An age-matched cohort analysis of the Utah Population Database

We determine the time to first live birth for female partners of males after a cancer diagnosis. Our group performed a retrospective, population-based, age-matched cohort study of Utah male residents diagnosed with cancer at age 18 years or later between 1956 and 2013 (exposed) matched to male Utah residents without cancer diagnosis (unexposed). Using stratified Cox proportional hazard models, we adjusted for race, ethnicity and number of live births prior to cancer diagnosis, to estimate the effect of time to a partner live birth following cancer diagnosis. Our study cohort included 19,303 men diagnosed with cancer (exposed) and 93,608 age-matched men without cancer diagnoses (unexposed). Exposed men were less likely to have a live birth prior to first cancer diagnosis (60.7% vs. 65.4%, p < 0.001) and after first cancer diagnosis (10.9% vs. 12.2%, p < 0.001) compared to unexposed men. Exposed men had a fertility hazard rate that was 31% lower after cancer diagnosis date than unexposed men (HR: 0.69; 95% CI: 0.65-0.72). This was most profound for men aged 18-30 years (HR: 0.59, 95% CI: 0.55-0.63). Male cancer survivors have a 31% lower female partner live birth rate after cancer diagnosis. These findings are important for patient counselling regarding fertility preservation at the time of cancer diagnosis.

Shared genetics between nonobstructive azoospermia and primary ovarian insufficiency

OBJECTIVE

Primary ovarian insufficiency (POI) and Non-obstructive azoospermia (NOA) both represent disease states of early, and often complete, failure of gametogenesis. Because oogenesis and spermatogenesis share the same conserved steps in meiosis I, it is possible that inherited defects in meiosis I could lead to shared causes of both POI and NOA. Currently, known genes that contribute to both POI and NOA are limited. In this review article, we provide a systematic review of genetic mutations in which both POI and NOA phenotypes exist.

EVIDENCE REVIEW

A PubMed literature review was conducted from January 1, 2000 through October 2020. We included all studies that demonstrated human cases of POI or NOA due to a specific genetic mutation either within the same family or in separate families.

RESULTS

We identified 33 papers that encompassed 10 genes of interest with mutations implicated in both NOA and POI. The genes were all involved in processes of meiosis I.

CONCLUSION

Mutations in genes involved in processes of meiosis I may cause both NOA and POI. Identifying these unique phenotypes among shared genotypes leads to biologic plausibility that the key error occurs early in gametogenesis with an etiology shared among both male and female offspring. From a clinical standpoint, this shared relationship may help us better understand and identify individuals at high risk for gonadal failure within families and suggests that clinicians obtain history for opposite sex family members when approaching a new diagnosis of POI or NOA.

Non-obstructive azoospermia: current and future perspectives

Infertility affects 1 in 6 couples, and male factor infertility has been implicated as a cause in 50% of cases. Azoospermia is defined as the absence of spermatozoa in the ejaculate and is considered the most extreme form of male factor infertility. Historically, these men were considered sterile but, with the advent of testicular sperm extraction and assisted reproductive technologies, men with azoospermia are able to biologically father their own children. Non-obstructive azoospermia (NOA) occurs when there is an impairment to spermatogenesis. This review describes the contemporary management of NOA and discusses the role of hormone stimulation therapy, surgical and embryological factors, and novel technologies such as proteomics, genomics, and artificial intelligence systems in the diagnosis and treatment of men with NOA. Moreover, we highlight that men with NOA represent a vulnerable population with an increased risk of developing cancer and cardiovascular comorbodities.

Lower total motile count is associated with smaller historic intergenerational family size: a pedigree analysis from the Utah Population Database

PURPOSE

To describe the association between contemporary total motile count (TMC), a measure of male factor infertility, and historic intergenerational family size.

METHODS

This is a retrospective, population-based, cohort study of men who underwent semen analysis for infertility workup at University of Utah, with at least a single measure of TMC, who were linked to extensive genealogical data. Two thousand one hundred eighty-two pedigree branches of men with a measure of TMC within the UPDB were identified. We identified the average number of generations and offspring within each generation. Conditional logistic regression models were used to assess the association between the risk of having a TMC in the 5th or 25th percentile and intergenerational family size. Generalized estimating equations (GEE) were used to assess the association between interval-level TMC and the number of ancestral offspring.

RESULTS

We found no association between intergenerational size and TMC within the 5th percentile (TMC < 4 million; RR = 0.97, 95% CI 0.93-1.01) or the 25th percentile (TMC < 62 million; RR = 1.00, 95% CI 0.97-1.03). When TMC was analyzed as a continuous variable, we found that lower TMC is associated with smaller intergenerational family size. For every additional child in their ancestral pedigree, we observed an increase in TMC of 1.88 million (p = 0.03). Men in the top quartile for intergenerational family size had a TMC that was 48 million higher than men in the bottom quartile (p = 0.047).

CONCLUSIONS

We found an association between TMC and ancestral family size, suggesting that lower TMC is associated with smaller intergenerational family size.

2021 European Thyroid Association Guideline on Thyroid Disorders prior to and during Assisted Reproduction

Severe thyroid dysfunction may lead to menstrual disorders and subfertility. Fertility problems may persist even after restoring normal thyroid function, and then an assisted reproductive technology (ART) may be a solution. Prior to an ART treatment, ovarian stimulation is performed, leading to high oestradiol levels, which may lead to hypothyroidism in women with thyroid autoimmunity (TAI), necessitating levothyroxine (LT4) supplements before pregnancy. Moreover, women with the polycystic ovarian syndrome and idiopathic subfertility have a higher prevalence of TAI. Women with hypothyroidism treated with LT4 prior to ART should have a serum TSH level <2.5 mIU/L. Subfertile women with hyperthyroidism planning an ART procedure should be informed of the increased risk of maternal and foetal complications, and euthyroidism should be restored and maintained for several months prior to an ART treatment. Fertilisation rates and embryo quality may be impaired in women with TSH >4.0 mIU/L and improved with LT4 therapy. In meta-analyses that mainly included women with TSH levels >4.0 mIU/L, LT4 treatment increased live birth rates, but that was not the case in 2 recent interventional studies in euthyroid women with TAI. The importance of the increased use of intracytoplasmic sperm injection as a type of ART on pregnancy outcomes in women with TAI deserves more investigation. For all of the above reasons, women of subfertile couples should be screened routinely for the presence of thyroid disorders.

Thyroid disorders and pathospermia in the ART clinic patients

OBJECTIVE

Over the past decade, a decrease in the semen quality in men of reproductive age, along with an increase in the incidence of thyroid diseases among young patients have been clearly noticed. The study was designed to determine various forms of pathospermia in the ART clinic patients with thyroid disorders.

MATERIALS AND METHODS

168 men of reproductive age in infertile marriage were examined. Men with male infertility factor associated with erectile dysfunction and normospermia (9 patients, 5.3%) were excluded. The study included 159 men and the patients were divided into three groups: the 1^st study group consisted of men with non-obstructive azoospermia - 11 men (6.9%); the 2^nd study group included men with other forms of pathospermia - 38 men (23.9%) and the control group consisted of men in infertile marriage with normospermia - 110 men (69.2%). All patients had anthropometric measurements, laboratory tests, thyroid and testicular ultrasonography. Spermogram was analyzed in accordance with the WHO classification, 5^th revision, 2010.

RESULTS

Among all examined men with pathospermia (n = 49 patients), 51.02% had various thyroid disorders, while it was firstly verified in 34.7% men. In 45.5% patients with non-obstructive azoospermia, previously undiagnosed nodular goiter with normal values of thyroid-stimulating hormone and free thyroxine were found, and a significant correlation between nodular goiter and the presence of azoospermia was revealed: r = 0.610, p = .01.

CONCLUSION.

Men with various forms of pathospermia and patients of the ART clinic had higher risks of thyroid disorders than in general population that could possibly affect fertility. Patients of the ART clinic with non-obstructive azoospermia are at risk for nodular thyroid disorders, even with normal values of thyroid function tests, and require thyroid ultrasonography.

Male Infertility and Somatic Health

Somatic health is associated with male infertility; potential links between infertility and health may arise from genetic, developmental, and lifestyle factors. Studies have explored possible connections between male infertility and oncologic, cardiovascular, metabolic, chronic, and autoimmune diseases. Male infertility also may be a predictor of hospitalization and mortality. Additional research is required to elucidate the mechanisms by which male infertility affects overall health.

New insights to guide patient care: the bidirectional relationship between male infertility and male health

Male reproduction is a complex process, and numerous medical conditions have the potential to alter spermatogenesis. In addition, male factor infertility may be a biomarker for future health. In the present review, we discuss the current literature regarding the association between systemic diseases and fertility, which may impact clinical outcomes or semen parameters. A number of conditions that have systemic consequences were identified, including genetic (e.g., cystic fibrosis, DNA mismatch repair alterations), obesity, psychological stress, exogenous testosterone, and a variety of common medications. As such, the infertility evaluation may offer an opportunity for health counseling beyond the discussion of reproductive goals. Moreover, male infertility has been suggested as a marker of future health, given that poor semen parameters and a diagnosis of male infertility are associated with an increased risk of hypogonadism, cardiometabolic disease, cancer, and even mortality. Therefore, male fertility requires multidisciplinary expertise for evaluation, treatment, and counseling.

Harnessing the full potential of reproductive genetics and epigenetics for male infertility in the era of "big data"

The complexity of male reproductive impairment has hampered characterization of the underlying genetic causes of male infertility. However, in the last 20 years, more powerful and affordable tools to interrogate the genetic and epigenetic determinants of male infertility have accelerated the number of new discoveries in the characterization of male infertility. With this explosion of new data, integration in a systems-based approach-including complete phenotypic information-to male infertility is imperative. We briefly review the current understanding of genetic and epigenetic causes of male infertility and how findings may be translated into a practical component for the diagnosis and treatment of male infertility.

Mortality in 43,598 men with infertility - a Swedish nationwide population-based cohort study

Background

Previous studies indicate a higher risk of comorbidity in men with infertility; however, research on mortality is scarce and the few studies that do exist have rarely differentiated between infertility and infertility-related diagnoses.

Objective

To examine mortality in men with an infertility or infertility-related diagnosis.

Design, setting, and participants

Population-based cohort study of men born in 1944–1992 in Sweden. We used Cox regression estimated hazard ratios (HRs) for infertility while adjusting for number of children, education, year of birth, country of birth, diabetes, hypertension, liver disease and end-stage renal disease. In all, 43,598 men with a diagnosis of infertility and 57,733 men with an infertility-related diagnosis were compared with 2,762,254 men (reference group) without such diagnoses.

Outcome measures

All-cause and cause-specific mortality at age 20 to 69 years.

Results and limitations

The 2,863,585 men in the study were followed for a median time of 22.0 years. During follow-up, 439 men with a diagnosis of infertility died, corresponding to a crude incidence rate of 1.56 deaths per 1,000 person-years. These figures can be compared with 1,400 deaths in men with an infertility-related diagnosis (1.96 deaths/1,000 person-years) and 99,463 deaths in reference individuals (2.17 deaths/1,000 person-years). Overall, men with a diagnosis of infertility did not have a higher risk of death (adjusted [a]HR=0.98; 95% confidence interval [95% CI]=0.89–1.08), but had a higher risk of death before age 30 (20–29 years) (aHR=3.26; 95% CI=2.42–4.41). This early excess mortality was largely explained by cancer diagnosed before infertility. Having an infertility-related diagnosis was associated with death (aHR=1.23; 95% CI=1.17–1.30). Limitations include the lack of general screening for infertility in Sweden and the lack of information on semen parameters.

Conclusion

Men with a diagnosis of infertility are not at a higher risk of death than the general population, although having a diagnosis related to infertility may be linked to a higher risk of death.

Patient summary

Men with a diagnosis of infertility do not seem to have a higher risk of death though an infertility-related diagnosis in men is associated with the risk of death.

Recent advances in understanding and managing male infertility

Infertility is a prevalent condition affecting an estimated 70 million people globally. The World Health Organization estimates that 9% of couples worldwide struggle with fertility issues and that male factor contributes to 50% of the issues. Male infertility has a variety of causes, ranging from genetic mutations to lifestyle choices to medical illnesses or medications. Recent studies examining DNA fragmentation, capacitation, and advanced paternal age have shed light on previously unknown topics. The role of conventional male reproductive surgeries aimed at improving or addressing male factor infertility, such as varicocelectomy and testicular sperm extraction, have recently been studied in an attempt to expand their narrow indications. Despite advances in the understanding of male infertility, idiopathic sperm abnormalities still account for about 30% of male infertility. With current and future efforts examining the molecular and genetic factors responsible for spermatogenesis and fertilization, we may be better able to understand etiologies of male factor infertility and thus improve outcomes for our patients.

gr/gr deletion predisposes to testicular germ cell tumour independently from altered spermatogenesis: results from the largest European study

The association between impaired spermatogenesis and TGCT has stimulated research on shared genetic factors. Y chromosome-linked partial AZFc deletions predispose to oligozoospermia and were also studied in TGCT patients with controversial results. In the largest study reporting the association between gr/gr deletion and TGCT, sperm parameters were unknown. Hence, it remains to be established whether this genetic defect truly represents a common genetic link between TGCT and impaired sperm production. Our aim was to explore the role of the following Y chromosome-linked factors in the predisposition to TGCT: (i) gr/gr deletion in subjects with known sperm parameters; (ii) other partial AZFc deletions and, for the first time, the role of partial AZFc duplications; (iii) DAZ gene dosage variation. 497 TGCT patients and 2030 controls from two Mediterranean populations with full semen/andrological characterization were analyzed through a series of molecular genetic techniques. Our most interesting finding concerns the gr/gr deletion and DAZ gene dosage variation (i.e., DAZ copy number is different from the reference sequence), both conferring TGCT susceptibility. In particular, the highest risk was observed when normozoospermic TGCT and normozoospermic controls were compared (OR = 3.7; 95% CI = 1.5-9.1; p = 0.006 for gr/gr deletion and OR = 1.8; 95% CI = 1.1-3.0; p = 0.013 for DAZ gene dosage alteration). We report in the largest European study population the predisposing effect of gr/gr deletion to TGCT as an independent risk factor from impaired spermatogenesis. Our finding implies regular tumour screening/follow-up in male family members of TGCT patients with gr/gr deletion and in infertile gr/gr deletion carriers.

Urologic conditions associated with malignancy

INTRODUCTION

Recent advances in cancer research have highlighted the role of genetics in malignancy. Genetic dysregulation of core cellular functions similarly influences benign conditions. These common genetic factors have led researchers to identify an association between certain urologic conditions and malignancy. The objective of this review is to evaluate the literature linking benign urologic conditions including male infertility, Peyronie's disease, cryptorchidism, and hypospadias, to malignancy.

METHODS

A search of PubMed was performed using the following search terms and their combinations: male infertility, female infertility, cancer, malignancy, mortality, male urologic conditions, azoospermia, Peyronie's disease, cryptorchidism, hypospadias, and genetics. Studies were assessed for quality and included or excluded based on study design and relevance to the topic of urologic conditions and malignancy.

RESULTS

A total of 52 studies were evaluated, of which 38 were included. Associations between male infertility and testicular cancer, prostate cancer, and other cancers including melanoma, bladder cancer, and thyroid cancer were examined. Several genetic alterations were found to be common in the pathogenesis of both male infertility and carcinogenesis. Associations between female infertility and breast, ovarian, and endometrial cancer are also assessed, as are the relationships between Peyronie's disease, cryptorchidism, and hypospadias and malignancy.

CONCLUSIONS

Recent work has identified associations between a number of malignancies and benign urologic conditions including male infertility, Peyronie's disease, cryptorchidism, and hypospadias. Molecular and genetic mechanisms have been proposed, but no definitive causal relationships have been identified to date. Future work will continue to better define the links between malignancy and benign urologic conditions and ultimately facilitate risk stratification, screening, and treatment of affected men.

Genetic intersection of male infertility and cancer

Recent epidemiological studies have identified an association between male factor infertility and increased cancer risk, however, the underlying etiology for the shared risk has not been investigated. It is likely that much of the association between the two disease states can be attributed to underlying genetic lesions. In this article we review the reported associations between cancer and spermatogenic defects, and through database searches we identify candidate genes and gene classes that could explain some of the observed shared genetic risk. We discuss the importance of fully characterizing the genetic basis for the relationship between cancer and male factor infertility and propose future studies to that end.

Testicular cancer

Testicular cancer is the most common malignancy among men between 14 and 44 years of age, and its incidence has risen over the past two decades in Western countries. Both genetic and environmental factors contribute to the development of testicular cancer, for which cryptorchidism is the most common risk factor. Progress has been made in our understanding of the disease since the initial description of carcinoma in situ of the testis in 1972 (now referred to as germ cell neoplasia in situ), which has led to improved treatment options. The combination of surgery and cisplatin-based chemotherapy has resulted in a cure rate of >90% in patients with testicular cancer, although some patients become refractory to chemotherapy or have a late relapse; an improved understanding of the molecular determinants underlying tumour sensitivity and resistance may lead to the development of novel therapies for these patients. This Primer provides an overview of the biology, epidemiology, diagnosis and current treatment guidelines for testicular cancer, with a focus on germ cell tumours. We also outline areas for future research and what to expect in the next decade for testicular cancer.

Limitations and opportunities in male fertility databases

Over the last several years, the male component of reproduction has begun to gain clinical momentum. The medical literature has traditionally focused on infertility from the female perspective, but recent publications have demonstrated that male infertility is an important marker of overall health for infertile men as well as their family members. In order to perform large-scale, quality research related to male infertility, comprehensive databases are necessary. Currently, research in male infertility is limited by the fact that there is not a centralized, comprehensive database specifically designed to collect patient information related to male fertility. A database of this nature exists for female infertility research in the form of the Society for Assisted Reproductive Technology (SART) clinical summary report and the National ART Surveillance System (NASS) published by the Centers for Disease Control (CDC). This review outlines the strengths and weaknesses of several male fertility data sources, including the National Survey of Family Growth, the Reproductive Medicine Network, the Andrology Research Consortium (ARC), the Truven Health MarketScan^® databases, the Utah Population Database, and data available from the Ober Lab related to the Hutterites. While each of these sources has been instrumental in the creation of meaningful research within the field of male fertility, a need remains for the creation of a centralized database for use in future male fertility research. The ideal database would consist of vast amounts of patient data which link individuals and couples to biologic specimens as well as data from family members, designed with parameters specifically purposed for male fertility research. The use of electronic medical records (EMR) systems such as Epic may play a role in the development of such a database going forward. At present, although some information is available through current databases, researchers must utilize suboptimal data sources to perform studies.