Trends in incidence of testicular cancer in boys and adolescent men

Maternal cigarette smoking during pregnancy and reproductive health in children: a review of epidemiological studies

Maternal cigarette smoking may affect the intrauterine hormonal environment during pregnancy and this early fetal exposure may have detrimental effects on the future trajectory of reproductive health. In this review, we discuss the epidemiological literature on the association between prenatal exposure to maternal cigarette smoking and several aspects of reproductive health. The literature points towards an increased risk of the urogenital malformation cryptorchidism, but a potential protective effect on the risk of hypospadias in sons following prenatal cigarette smoking exposure. Studies on sexual maturation find a tendency towards accelerated pubertal development in exposed boys and girls. In adult life, prenatally exposed men have impaired semen quality compared with unexposed individuals, but an influence on fecundability, that is, the biological ability to reproduce, is less evident. We found no evidence to support an association between prenatal cigarette smoking exposure and testicular cancer. Among adult daughters, research is sparse and inconsistent, but exposure to cigarette smoking in utero may decrease fecundability. In conclusion, prenatal exposure to cigarette smoking may cause some long-term adverse effects on the reproductive health.

Liposome: classification, preparation, and applications

Liposomes, sphere-shaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid-60s. Today, they are a very useful reproduction, reagent, and tool in various scientific disciplines, including mathematics and theoretical physics, biophysics, chemistry, colloid science, biochemistry, and biology. Since then, liposomes have made their way to the market. Among several talented new drug delivery systems, liposomes characterize an advanced technology to deliver active molecules to the site of action, and at present, several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles to 'second-generation liposomes', in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability and regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents.

Environmental epigenetics: prospects for studying epigenetic mediation of exposure-response relationships

Changes in epigenetic marks such as DNA methylation and histone acetylation are associated with a broad range of disease traits, including cancer, asthma, metabolic disorders, and various reproductive conditions. It seems plausible that changes in epigenetic state may be induced by environmental exposures such as malnutrition, tobacco smoke, air pollutants, metals, organic chemicals, other sources of oxidative stress, and the microbiome, particularly if the exposure occurs during key periods of development. Thus, epigenetic changes could represent an important pathway by which environmental factors influence disease risks, both within individuals and across generations. We discuss some of the challenges in studying epigenetic mediation of pathogenesis and describe some unique opportunities for exploring these phenomena.

Trends in incidence and survival of pediatric and adolescent patients with germ cell tumors in the United States, 1975 to 2006

BACKGROUND

Pediatric germ cell tumors (GCTs) are rare and heterogeneous tumors with uncertain etiology. In the current study, data from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program were used to evaluate trends in incidence and survival of GCTs in boys and girls ages ≤19 years. To the authors' knowledge, few studies to date have evaluated trends in pediatric GCTs. Results from these analyses may provide clues to the etiology of GCTs.

METHODS

Frequencies, incidence rates, and 5-year relative survival rates stratified by sex were evaluated overall and by demographic subgroups based on age (birth to 9 years and 10-19 years), race (white, black, and other), and ethnicity (non-Hispanic and Hispanic) as sample size permitted.

RESULTS

In whites, the incidence of GCTs was lower for females than males in the 10-year to 19-year age group (rate ratio [RR], 0.47; 95% confidence interval [95% CI], 0.42-0.53), whereas the rates were similar in the age group for birth to 9 years. In contrast, incidence rates were higher in black females than in black males in both age groups (RR, 2.01 [95%CI, 1.08-3.84] in those ages birth to 9 years; RR, 3.30 [95% CI, 2.13-5.28] in those ages 10-19 years). The incidence of ovarian GCT was significantly higher in Hispanic compared with non-Hispanic girls in the groups aged 10 to 19 years. Incidence rates increased during the study period in boys ages 10 to 19 years (annual percentage change [APC], 1.2; 95% CI, 0.4-2.1) and girls ages birth to 9 years (APC, 1.9; 95% CI, 0.3-2.5).

CONCLUSIONS

The incidence of pediatric GCTs in the United States appears to be increasing only in certain subgroups, suggesting that the etiology is not completely overlapping in all age groups. Differences in incidence patterns by race and ethnicity merit further investigation.

International trends in the incidence of testicular cancer, 1973-2002

BACKGROUND

Whereas testicular cancer incidence rates have been widely reported in populations of Northern European ancestry, rates in other populations have been less frequently examined. In a prior report, global testicular cancer incidence rates and trends for the years 1973 to 1997 were summarized. The current report extends these analyses with an additional 5 years of data from Cancer Incidence in Five Continents.

METHODS

Age-standardized incidence rates over successive 5-year time periods were obtained for populations in the Americas, Asia, Europe, and Oceania.

RESULTS

In general, testicular cancer incidence remained highest in Northern European populations (8.0-9.0 per 100,000) and lowest in Asian and African populations (<1 per 100,000). One notable exception to this pattern, however, was the very high rate reported by the Valdivia, Chile registry (8.8 per 100,000). In many populations, rates rose between 1973 and 2002, although the increases were strongest and most consistent among populations of European ancestry. In certain European populations, such as those of Denmark and of Geneva, Switzerland, some recent plateauing of rates was evident. There was little evidence of increase and possible evidence of a modest decline in rates among east Asian populations. Trends by histology (seminoma and nonseminoma) were generally similar to one another.

CONCLUSIONS

Risk of testicular cancer remains relatively high in Northern European populations and low in Asian and African populations. Similar trends by histology suggest common risk factors. EFFECT: Reasons for increasing rates among Northern Europeans and stable or declining rates among East Asians are unexplained, supporting the need for future etiologic studies.

Monitoring the decreasing trend of testicular cancer mortality in Spain during 2005-2019 through a Bayesian approach

PURPOSE

To assess time trends of testicular cancer (TC) mortality in Spain for period 1985-2019 for age groups 15-74 years old through a Bayesian age-period-cohort (APC) analysis.

METHODS

A Bayesian age-drift model has been fitted to describe trends. Projections for 2005-2019 have been calculated by means of an autoregressive APC model. Prior precision for these parameters has been selected through evaluation of an adaptive precision parameter and 95% credible intervals (95% CRI) have been obtained for each model parameter.

RESULTS

A decrease of -2.41% (95% CRI: -3.65%; -1.13%) per year has been found for TC mortality rates in age groups 15-74 during 1985-2004, whereas mortality showed a lower annual decrease when data was restricted to age groups 15-54 (-1.18%; 95% CRI: -2.60%; -0.31%). During 2005-2019 is expected a decrease of TC mortality of 2.30% per year for men younger than 35, whereas a leveling off for TC mortality rates is expected for men older than 35.

CONCLUSIONS

A Bayesian approach should be recommended to describe and project time trends for those diseases with low number of cases. Through this model it has been assessed that management of TC and advances in therapy led to decreasing trend of TC mortality during the period 1985-2004, whereas a leveling off for these trends can be considered during 2005-2019 among men older than 35.

Time trends in the incidence of testicular cancer in childhood and young adulthood

BACKGROUND

There has been a steep increase in the incidence of adult testicular cancer in many populations, but in spite of numerous studies, the etiology of testicular cancer remains elusive. The time trends of childhood testicular tumors are less clear and have been studied in a few populations. To further evaluate whether or not adult and childhood cancers share trend determinants and whether future adult testicular cancer incidences can be predicted through childhood testicular cancer incidences, their rates were compared.

METHOD

Data on testicular cancer incidence in childhood and in young adulthood were extracted from the IARC Cancer Incidence in the Five Continents Database limited to two 10-year time periods (1967-1976 and from 1987-1996) to allow for truncation-free analyses within the same birth cohort.

RESULTS

Childhood testicular cancer incidence varied 3- to 4-fold, whereas adult testicular cancer incidence varied 10- to 11-fold between the studied populations. No positive correlation between childhood and adulthood incidence of testicular cancer was found.

CONCLUSION

These data indicate that the incidence of testicular cancer in adulthood is influenced by factors, either prenatal or postnatal exposures different than those determining the trends among children.

Sex-specific incidence and temporal trends in solid tumours in young people from Northern England, 1968-2005

BACKGROUND

This study examined sex-specific patterns and temporal trends in the incidence of solid tumours in the Northern Region of England from 1968 to 2005. This updates earlier analyses from the region where sex was not considered in depth. Sex-specific analyses were carried out to determine whether sex differences might provide clues to aetiology.

METHODS

Details of 3576 cases, aged 0-24 years, were obtained from a specialist population-based cancer registry. There were 1843 males (886 aged 0-14 years and 957 aged 15-24 years) and 1733 females (791 aged 0-14 years and 942 aged 15-24 years). Age-standardized incidence rates (per million population) were calculated. Linear regression was used to analyze temporal trends in incidence and annual percentage changes were estimated. Analyses were stratified by sex and by age-group.

RESULTS

There were marked differences in incidence patterns and trends between males and females and also between age-groups. For males central nervous system (CNS) tumours formed the largest proportion of under-15 cases and germ cell tumours was the largest group in the 15-24's, whilst for females CNS tumours dominated in the under-15's and carcinomas in the older group. For 0-14 year olds there were male-specific increases in the incidence of rhabdomyosarcoma (2.4% per annum; 95% CI: 0.2%-4.5%) and non-melanotic skin cancer (9.6%; 95% CI: 0.0%-19.2%) and female-specific increases for sympathetic nervous system tumours (2.2%; 95% CI: 0.4%-3.9%), gonadal germ cell tumours (8.6%; 95% CI: 4.3%-12.9%) and non-gonadal germ cell tumours (5.4%; 95% CI: 2.8%-7.9%). For 15-24 year olds, there were male-specific increases in gonadal germ cell tumours (1.9%; 95% CI: 0.3%-3.4%), non-gonadal germ cell tumours (4.4%; 95% CI: 1.1%-7.7%) and non-melanotic skin cancer (4.7%; 95% CI: 0.5%-8.9%) and female-specific increases for osteosarcoma (3.5%; 95% CI: 0.5%-6.5%), thyroid cancer (2.8%; 95% CI: 0.1%-5.6%) and melanoma (4.6%; 95% CI: 2.2%-7.1%).

CONCLUSION

This study has highlighted notable differences between the sexes in incidence patterns and trends for solid tumours. Some of these sex-specific differences could have been obscured if males and females had been analysed together. Furthermore, they suggest aetiological differences or differential susceptibility to environmental factors between males and females.

Public health implications of altered puberty timing

Changes in puberty timing have implications for the treatment of individual children, for the risk of later adult disease, and for chemical testing and risk assessment for the population. Children with early puberty are at a risk for accelerated skeletal maturation and short adult height, early sexual debut, potential sexual abuse, and psychosocial difficulties. Altered puberty timing is also of concern for the development of reproductive tract cancers later in life. For example, an early age of menarche is a risk factor for breast cancer. A low age at male puberty is associated with an increased risk for testicular cancer according to several, but not all, epidemiologic studies. Girls and, possibly, boys who exhibit premature adrenarche are at a higher risk for developing features of metabolic syndrome, including obesity, type 2 diabetes, and cardiovascular disease later in adulthood. Altered timing of puberty also has implications for behavioral disorders. For example, an early maturation is associated with a greater incidence of conduct and behavior disorders during adolescence. Finally, altered puberty timing is considered an adverse effect in reproductive toxicity risk assessment for chemicals. Recent US legislation has mandated improved chemical testing approaches for protecting children's health and screening for endocrine-disrupting agents, which has led to changes in the US Environmental Protection Agency's risk assessment and toxicity testing guidelines to include puberty-related assessments and to the validation of pubertal male and female rat assays for endocrine screening.

Secular decline in male testosterone and sex hormone binding globulin serum levels in Danish population surveys

CONTEXT

Adverse secular trends in male reproductive health have been reported to be reflected in increased testicular cancer risk and decreased semen quality in more recently born men. These secular trends may also be reflected by changes in Leydig cell function.

OBJECTIVE

The objective of the study was to examine whether an age-independent time trend in male serum testosterone levels exists.

DESIGN AND SETTING

Testosterone and SHBG were analyzed in 5350 male serum samples from four large Danish population surveys conducted in 1982-1983, 1986-1987, 1991-1992, and 1999-2001. Free testosterone levels were calculated. The effects of age, year of birth, and time period on hormone levels were estimated in a general linear statistical model.

MAIN OUTCOME MEASURES

Testosterone, SHBG, and calculated free testosterone levels in Danish men in relation to age, study period, and year of birth were measured.

RESULTS

Serum testosterone levels decreased and SHBG levels increased with increasing age. In addition to this expected age effect, significant secular trends in testosterone and SHBG serum levels were observed in age-matched men with lower levels in the more recently born/studied men. No significant age-independent effect was observed for free testosterone. Adjustment for a concurrent secular increase in body mass index reduced the observed cohort/period-related changes in testosterone, which no longer were significant. The observed cohort/period-related changes in SHBG levels remained significant after adjustment for body mass index.

CONCLUSIONS

The observed age-independent changes in SHBG and testosterone may be explained by an initial change in SHBG levels, which subsequently lead to adjustment of testosterone at a lower level to sustain free testosterone levels.

Testicular Cancer Variations in Time and Space in Europe

OBJECTIVES

Testicular cancer (TC) is the most common malignancy in young men. A review of all published articles on TC incidence revealed an increased incidence in Northern and Central Europe. We extended the analysis to the whole of Europe by using all data available, notably from registries.

METHODS

We performed a PubMed search and selected articles dealing with TC incidence. We obtained additional information from data of European registries through the eight volumes of the Cancer Incidence in Five Continents, IARC Scientific Publications.

RESULTS

Since the Second World War, TC incidence has been increasing in nearly all European countries. It has doubled in several countries, including France, since 1970. We observed that the increase followed a gradient: the highest rate is centred in Denmark and Germany, and decreases progressively in a centrifugal manner.

CONCLUSIONS

TC incidence is increasing throughout Europe, but wide discrepancies exist between the different countries. The reasons for such a phenomenon are still unclear although environmental factors are strongly suspected, which could have an impact on male fertility. From a public health perspective, further research using cases collected through national and regional population-based registers and case-control studies must be strongly encouraged.

Incidence and survival for testicular germ cell tumor in young males: a report from the Northern Region Young Person's Malignant Disease Registry, United Kingdom

The incidence of testicular cancer has increased markedly in most developed countries, although the reasons for this are unclear. In this study, 253 patients with testicular cancer diagnosed younger than 25 years from 1968-1999 were identified from the Northern Region Young Persons' Malignant Disease Registry. The age-standardized incidence rate increased from 0.93 in 1968-1978 to 1.60 per 100,000 in 1990-1999. The increase in incidence was confined to those patients >15 years old, with the rate in younger children remaining very low. The 5-year survival increased significantly from 46% (95% confidence interval [CI] 33% to 58%) to 92% (95% CI 85% to 96%) during 1968-1999 and was significantly higher for seminoma than nonseminoma, 91% (95% CI 78% to 96%) and 77% (95% CI 70% to 82%), respectively. Although increased surveillance and public health campaigns designed to raise awareness of the disease and the advantages of self-examination should continue, further research is required into the etiology of this relatively common cancer among young males.

Ten-year survival and risk of relapse for testicular cancer: A EUROCARE high resolution study

Effective treatments for testicular cancer have been available since the 1970s, yet EUROCARE uncovered marked inter-country survival differences for this disease. To investigate these differences, we reviewed clinical records of 1350 testicular cancer cases diagnosed during 1987-1992 from 13 population-based cancer registries in nine European countries. Patients were followed up for life status and relapse. Ten-year observed survival was estimated by the Kaplan-Meier method. Cox multivariable analyses were performed separately for seminomas and non-seminomas. Overall, 66% of seminomas and 36% of non-seminomas were limited to the testis. Ten-year survival was 63% (Estonia) to 94% (Switzerland, Slovenia) for seminoma; 47% (Estonia) to 90% (Yorkshire, UK, The Netherlands) for non-seminoma. Multivariable analysis adjusted for country, age and stage showed that hazard ratios (HRs) of death differed little between western European registries, and were mainly attributable to differing stage at diagnosis. Significantly higher than reference HRs in Estonia and Poland suggest inadequacy or unavailability of treatments.

Trends in testicular cancer incidence and mortality in 22 European countries: continuing increases in incidence and declines in mortality

This study profiles testicular cancer incidence and mortality across Europe, and the effects of age, period and generational influences, using age-period-cohort modeling. Despite a 5-fold variation in incidence rates, there were consistent mean increases in incidence in each of the 12 European countries studied, ranging from around 6% per annum (Spain and Slovenia) to 1-2% (Norway). In contrast, declines in testicular cancer mortality of 3-6% per annum were observed in the 1980s and 1990s for the majority of the 22 countries studied, particularly in Northern and Western Europe. The mortality trends in several European countries were rather stable (Romania and Bulgaria) or increasing (Portugal and Croatia). Short-term attenuations in increasing cohort-specific risk of incidence were indicated among men born between 1940 and 1945 in 7 European countries. In Switzerland, successive generations born from the mid 1960s may have experienced a steadily declining risk of disease occurrence. While the underlying risk factors responsible remain elusive, the temporal and geographical variability in incidence may point to an epidemic in different phases in different countries-the result of country-specific differences in the prevalence of one or several ubiquitous and highly prevalent environmental determinants of the disease. Advances in treatment have led to major declines in mortality in many European countries from the mid 1970s, which has translated to cohorts of men at successively lower risk of death from the disease. Slower progress in the delivery of optimal care is however evident from the mortality trends in several lower-resource countries in Southern and Eastern Europe. The first beneficiaries of therapy in these populations may be those men born--rather than diagnosed--in the era of major breakthrough in testicular cancer care.

Epidemiology of testicular cancer: An overview

Testicular cancer is a rare disease, accounting for 1.1% of all malignant neoplasms in Canadian males. Despite the low overall incidence of testicular cancer, it is the most common malignancy among young men. The incidence rate of testicular cancer has been increasing since the middle of the 20th century in many western countries. However, the etiology of testicular cancer is not well understood. A search of the peer-reviewed literature was conducted to identify important articles for review and inclusion in this overview of the epidemiology of testicular cancer. Most of the established risk factors are related to early life events, including cryptorchidism, carcinoma in situ and in utero exposure to estrogens. Occupational, lifestyle, socioeconomic and other risk factors have demonstrated mixed associations with testicular cancer. Although there are few established risk factors for testicular cancer, some appear to be related to hormonal balance at various life stages. Lifestyle and occupational exposures occurring later in life may play a role in promoting the disease, although they are not likely involved in cancer initiation. In addition to summarizing the current epidemiologic evidence on risk factors for testicular cancer, we suggest future research directions that may elucidate the etiology of testicular cancer.

International patterns and trends in testis cancer incidence

Although the incidence of testis cancer has risen markedly in many Western populations over the past half-century, it is not clear whether rates in other populations also have increased. To clarify this issue, we examined testis cancer incidence rates over the 25-year time period of 1973-1997 for selected populations around the world. Age-standardized incidence rates for 21 registries in the Americas, Asia, Europe and Oceania over successive 5-year time periods were obtained from volumes 4-8 of Cancer Incidence in Five Continents. Testis cancer rates rose between 1973 and 1997 in most populations worldwide, although the increases were strongest and most consistent among populations of European ancestry. Rates appear to be leveling off in some populations. The increases in testis cancer remain unexplained, although changes in the prevalence of important risk factors for this disease may be responsible.

Increasing incidence of testicular cancer worldwide: a review

PURPOSE

Testicular cancer (TC) is the most common malignancy in 20 to 34-year-old men. Numerous publications have shown an increase in the incidence of testis cancer in the last 40 years with substantial differences among countries. We evaluated worldwide variations in testicular cancer incidence and compared trends in different regions in the world.

MATERIALS AND METHODS

We reviewed 441 studies provided by a MEDLINE search using the key words testis/testicular, cancer/tumor and incidence that were published between 1980 and 2002. From these articles we selected only those devoted to testis cancer incidence and of them only the most recent studies from each country or region. Nevertheless, articles using the same data base but providing new and additional information, for example differences among ethnic groups or controversial explanations for trends, were also retained. We selected 30 articles and analyzed their methodological approach and main results.

RESULTS

Worldwide we observed a clear trend toward an increased TC incidence in the last 30 years in the majority of industrialized countries in North America, Europe and Oceania. Nevertheless, surprising differences in incidence rates were seen between neighboring countries (Finland 2.5/100,000 cases versus Denmark 9.2/100,000) as well as among regions of the same country (2.8 to 7.9/100,000 according to various regional French registers). In addition, substantial differences in the TC incidence and trends were observed among ethnic groups. The increase in the TC incidence was significantly associated with a birth cohort effect in the United States and in European countries. To date except for cryptorchidism no evident TC risk factor has been clearly demonstrated, although the environmental hypothesis with a key role of endocrine disrupters has been put forward by several groups.

CONCLUSIONS

Such a recent increase in the TC rate in most industrialized countries should lead urologists and andrologists to give more attention to testicular cancer symptoms in adolescents and young adults. In a public health perspective further research using cases collected through national and regional population based registers and case-control studies must be strongly encouraged if we wish to be able to assess future trends in TC incidence rates and also identify risk factors.

Current perspectives in cancer proteomics

Proteome technology has been used widely in cancer research and is a useful tool for the identification of new cancer markers and treatment-related changes in cancer. This article details the use of proteome technology in cancer research, and laboratory-based and clinical cancer research studies are described. New developments in proteome technology that enable higher sample-throughput are evaluated and methods for enhancing conventional proteome analysis (based on two-dimensional electrophoresis) discussed. The need to couple laboratory-based proteomics research with clinically relevant models of the disease is also considered, as this remains the next main challenge of cancer-related proteome research.

Clues to the aetiological heterogeneity of testicular seminomas and non-seminomas: time trends and age-period-cohort effects

BACKGROUND

Most previous epidemiological studies have treated testicular cancer as a single entity. However, some investigators suggest that testicular seminomas and non-seminomas may have different risk profiles. We examine the time trends in incidence of the two main histological types separately.

METHODS

From 1970 through 1995, 7296 cases of testicular cancer were registered in the Canadian provinces of Ontario, Saskatchewan and British Columbia. In addition to analyses of the secular trends by age group and birth cohort, an age-period-cohort (APC) model with standard Poisson assumptions was fitted to the data to assess the time effects.

RESULTS

The age-adjusted incidence rate for seminomas increased by 53%, from 1.5 per 100 000 males in 1970-1971 to 2.3 per 100 000 males in 1994-1995. Non-seminomas increased by 91%, from 1.1 to 2.1 per 100 000 males over the same period. Non-seminomas were more frequent at young ages whereas seminomas dominated in older ages. In contrast to seminomas, non-seminomas occurred predominantly among adolescent men (15-19 years), with a fourfold increase between 1970-1971 and 1994-1995. Age-period-cohort modelling showed that the increase in the risk of both seminomas and non-seminomas followed a birth cohort pattern, but with differences in birth cohorts in addition to significantly distinct age patterns.

CONCLUSIONS

Our findings support the hypothesis postulating aetiological heterogeneity in the development of seminomas and non-seminomas. We suggest that epidemiological studies of testicular cancer treat seminomas and non-seminomas separately.

Incidence of testicular germ-cell malignancies in England and Wales: trends in children compared with adults

The incidence of testicular cancer has been increasing markedly in most industrialised countries. This rise is known to have affected young adults, but it is less clear whether it has affected other age groups, particularly children. We used data from the National Cancer Registry file at the Office of National Statistics (ONS) and the National Registry of Childhood Tumours to examine trends in testicular germ-cell malignancies overall in England and Wales from 1962 to 1990 and in children from 1962 to 1995. The incidence of testicular cancer at all ages rose by 3.4% (95% CI 3.3-3.6%) per annum from 1962 to 1990. A similar rise in the incidence of germ-cell malignancies occurred during the years for which histological information was available in the ONS files, 1971-1989 (3.4%; 3.1-3.6%), to which both seminomas and non-seminomas contributed equally. The incidence of non-seminomas in adults rose in men under age 55 years and declined in older men, whereas there were increases in the incidence of seminomas in both young and older men. Cohort analysis at young ages showed a marked rise in the risk of germ-cell malignancies up to the cohort born in 1955-1959 but no further rise for those born subsequently. The rise in the incidence of these tumours in young adults was paralleled by a similar trend, although less marked, in children aged under 15 years (1.3% per annum; 0.2-2.5%). The increase in risk for children in this very large data set alongside the rise in young adults is compatible with the hypothesis that childhood and adult testicular germ-cell malignancies may have some common risk factors, presumably pre-natal.

Birth cohort effects underlying the increasing testicular cancer incidence in Canada

PURPOSE

To examine the pattern of testicular cancer incidence by age, time period and birth cohort since 1969 in Canada.

METHODS

In addition to analyses of the secular trends by age group and birth cohort separately, an age-period-cohort model and the submodels with standard Poisson assumptions were fitted to the data.

RESULTS

The overall age-adjusted incidence of testicular cancer increased in Canada, from 2.8 per 100,000 males in 1969-71 to 4.2 in 1991-93. The younger age groups showed much higher absolute incidence rates in the recent period compared with those in the early period. Age-period-cohort modelling of data restricted to males aged 20-84 years suggested that the observed increase in testicular cancer could be largely attributed to a birth cohort effect. A steady increase in risk was observed among men born since 1945; those born between 1959 and 1968 were 2.0 (95% CI, 1.5-2.6) times as likely to develop testicular cancer as those born between 1904 and 1913.

CONCLUSION

The risk of testicular cancer has increased over time and changing exposure to environmental factors early in life may be responsible for this.

Testicular and paratesticular tumours in children: 30 years' experience

BACKGROUND

Testicular or paratesticular tumours in children are rare, making it difficult to achieve the best management for these life-threatening diseases. The aim of this study is to review patients during a 30-year period with these tumours and assess clinical aspects to improve management.

METHODS

The records of 68 patients from 1967 to 1996 were reviewed with respect to age at diagnosis, affected sites, presentation, clinical diagnosis, operation, pathology and prognosis.

RESULTS

The most common presentation was a painless scrotal mass (84%). The most common testicular tumour was mature teratoma (n = 27) followed by yolk sac tumour (n = 17). Thirteen patients had paratesticular rhabdomyosarcoma. Two teratocarcinomas, three leydig cell tumours, two sertoli cell tumours, one granulosa cell tumour, one fibroma, one gonadoblastoma, and one secondary tumour from acute myeloid leukaemia were found also. Testis-sparing surgery was performed in 21 of 33 patients with benign tumours (27 teratoma, three leydig cell tumours, two sertoli cell tumours, one fibroma), which caused no recurrence. Only two patients with rhabdomyosarcoma and one with mixed germ cell tumour died of their disease.

CONCLUSION

Recent combined therapy with surgery and chemotherapy against primary testicular and paratesticular tumours has improved prognosis. Testis-sparing surgery should be considered for benign tumours.

Detection of human endogenous retrovirus type K-specific transcripts in testicular parenchyma and testicular germ cell tumors of adolescents and adults: clinical and biological implications

Testicular germ cell tumors (TGCTs) of adolescents and adults have been shown to contain proteins of the human endogenous retrovirus type K family. In a recent study, expression of these retroviral sequences was confirmed using in situ hybridization, which also showed expression in carcinoma in situ, the precursor of all TGCTs. Because of the clinical significance of a test for early diagnosis of TGCTs, we studied whether expression of human endogenous retrovirus type K genes could be an informative parameter. Therefore, we investigated TGCTs of various histologies and testicular parenchyma with and without carcinoma in situ using reverse transcription-polymerase chain reaction for expression of the gag, env, and prt genes. The gag and prt genes were expressed in all samples tested. The env transcripts were not found in TGCTs showing somatic differentiation only but could be detected in most normal testicular parenchyma samples. Therefore, detection of human endogenous retrovirus type K transcripts cannot be used for early diagnosis of TGCTs. Simultaneous expression of multiple gag sequences was found both in normal parenchyma and TGCTs, and we demonstrated that expression of gag sequences with an extra G, necessary to generate a functional protein, was not limited to TGCTs.

The platelet-derived growth factor alpha-receptor 1.5 kb transcript: target for molecular detection of testicular germ cell tumours of adolescents and adults

An accurate and relatively simple method to detect testicular germ cell tumours of adolescents and adults (TGCTs) could be useful for early detection and may help to avoid unnecessary orchidectomies. We report a highly sensitive reverse-transcription polymerase chain reaction assay for the 1.5 kb transcript of the platelet-derived growth factor-alpha receptor for molecular diagnosis of TGCTs. As a simulation of the clinical application of the assay the approach was applied on through-cut-biopsies from orchidectomy specimens. In a series of 31 specimens, the 1.5 kb transcript was detected in all samples containing either carcinoma in situ, or an invasive TGCT, with mature teratoma as only exception. No expression was detected in normal parenchyma. On the basis of the through-cut-biopsies the assay shows a sensitivity of 0.87 and a specificity of 1.00. The positive and negative predictive values of the test are 1.00 and 1.00. For carcinoma in situ alone these values are 0.86, 1.00, 1.00, and 0.80, respectively. The figures at least equal the results obtained with the most sensitive morphological/enzyme-histochemical study of duplicate biopsies. We conclude that the 1.5 kb transcript of the platelet-derived growth factor-alpha receptor is a useful molecular marker for TGCTs, and therefore of interest in a clinical setting.

Increasing incidence of testicular cancer--birth cohort effects

The incidence of testicular cancer is rising in most Western populations. A collaborative study between nine population-based cancer registries in countries around the Baltic Sea was utilized in order to analyze in detail geographic variations and temporal trends in the occurrence of testicular cancer. There were 34,309 cases registered up until 1989 starting in Denmark in 1942 and most recently in Latvia in 1977. From the descriptive epidemiology it was obvious that there was a substantial variation in the age-standardized incidence amounting to about a 10-fold difference between the different countries ranging from 0.8 per 100,000 person-years in Lithuania to 7.6 per 100,000 person-years in Denmark. Previous studies have indicated that this increase is due to birth cohort effects. A more detailed analysis was therefore performed in those six countries with a sufficiently long period of cancer registration; Poland, former East Germany, Norway, Finland, Denmark and Sweden. This analysis showed that birth cohort is a more important determinant of testicular cancer risk than year of diagnosis. In Poland, former East Germany and Finland, there was an increasing risk for all birth cohorts. Among men born in Denmark, Norway or Sweden between 1930 and 1945, this increasing trend in risk was interrupted in these birth cohorts but followed thereafter by an uninterrupted increase by birth cohort. In conclusion, life time exposure to environmental factors which are associated with the incidence of testicular cancer appear to be more related to birth cohort than to year of diagnosis. Because testicular cancer typically occurs at an early age, major etiological factors therefore need to operate early in life, perhaps even in utero.

Trends in sex-ratio, testicular cancer and male reproductive hazards: are they connected?

In the last few decades, the male proportion of newborn babies has been decreasing in several populations. The changes are very small and without practical importance per se, but the underlying biological mechanisms are not known. In the same period, testicular cancer incidence has increased, and there has been indications of decreasing sperm counts in men in several populations. The available knowledge on factors that influence the sex-ratio in humans supports the idea that an excess of girls in the offspring of a man may be an indicator of reproductive hazards. Data from a Danish case-control study show strong associations between testicular cancer, low fertility and a low M:F sex-ratio in the offspring. It is proposed as a hypothesis that there may exist common aetiological factors for testicular cancer, low fertility and low offspring sex-ratio, and that a search for the causal factors involved may focus on agents that can act prenatally to disrupt the normal development and differentiation of the male reproductive organs.

Methylation similarities of two CpG sites within exon 5 of human H19 between normal tissues and testicular germ cell tumours of adolescents and adults, without correlation with allelic and total level of expression

Testicular germ cell tumours (TGCTs) of adolescents and adults morphologically mimic different stages of embryogenesis. Established cell lines of these cancers are used as informative models to study early development. We found that, in contrast to normal development, TGCTs show a consistent biallelic expression of imprinted genes, including H19, irrespective of histology. Methylation of particular cytosine residues of H19 correlates with inhibition of expression, which has not been studied in TGCTs thus far. We investigated the methylation status of two CpG sites within the 3' region of H19 (exon 5: positions 3321 and 3324) both in normal tissues as well as in TGCTs. To obtain quantitative data of these specific sites, the ligation-mediated polymerase chain reaction technique, instead of Southern blot analysis, was applied. The results were compared with the allelic status and the total level of expression of this gene. Additionally, the undifferentiated cells and differentiated derivatives of the TGCT-derived cell line NT2-D1 were analysed. While peripheral blood showed no H19 expression and complete methylation, a heterogeneous but consistent pattern of methylation and level of expression was found in the other normal tissues, without a correlation between the two. The separate histological entities of TGCTs resembled the pattern of their nonmalignant tissues. While the CpG sites remained completely methylated in NT2-D1, H19 expression was induced upon differentiation. These data indicate that methylation of the CpG sites within exon 5 of H19 is tissue dependent, without regulating allelic status and/or total level of expression. Of special note is the finding that, also regarding methylation of these particular sites of H19, TGCTs mimic their non-malignant counterparts, in spite of their consistent biallelic expression.

Risks of testicular cancer and cryptorchidism in relation to socio-economic status and related factors: case-control studies in Denmark

To explore risk factors for testicular cancer and cryptorchidism, 2 parallel case-control studies were conducted in Denmark. The testicular-cancer study was population-based and included 514 cases and 720 controls. The cryptorchidism study included 387 cases and 416 controls and was based on 2 hospital series of men treated for cryptorchidism and a control group sampled among residents in the Copenhagen area. The 2037 men were interviewed by telephone, and self-administered questionnaires were sent to their mothers. A strong association was seen between low social class and cryptorchidism, with sons of unskilled workers having a 3-fold higher risk of cryptorchidism than sons of self-employed men. Testicular cancer was only moderately associated with high-social-class indicators, and only with such indicators pertaining to the mother. Both testicular cancer and cryptorchidism tended to occur more frequently in first-born men and in sons of older women but these associations were not statistically significant. Late puberty was associated with reduced risk of testicular cancer. The effect of age at puberty may be due both to advanced age at diagnosis and to the existence of common determinants of age at puberty and testicular cancer. Men who had been treated for cryptorchidism entered puberty later than other men, possibly because of impaired hormonal function of the testes. There was no indication of increased risk of testicular cancer or cryptorchidism in sons of mothers who smoked around the time of conception or during the pregnancy.