Hormonal risk factors in testicular cancer. A case-control study

Sibling relatedness and pubertal development in girls and boys: A population-based cohort study

PURPOSE

To investigate the association between sibling relatedness and pubertal development in girls and boys.

METHODS

This cohort study consisted of 10,657 children from the Puberty Cohort, Denmark. Information on sibling relatedness was obtained by self-report. Information on pubertal markers was obtained half yearly from age 11 and throughout puberty. Mean age difference at attaining pubertal markers was estimated using interval-censored regression models according to sibling relatedness (full, half and/or step siblings; half and/or step siblings; no siblings; relative to full siblings).

RESULTS

Girls with both full, half and/or step siblings (-1.2 (CI 95 %: -2.5; 0.1) months), only half- and/or stepsiblings (-2.2 (CI 95 %: -3.7; -0.7) months), and no siblings (-5.5 (CI 95 %: -8.5; -2.5) months) entered puberty earlier than girls with full siblings. Boys with full, half and/or step siblings (-1.4 (CI 95 %: -2.7; -0.1) months), only half and/or step siblings (-1.2 (CI 95 %: -3.0; 0.6) months), and no siblings (-4.5 (CI 95 %: -8.8; -0.3) months) entered puberty earlier than boys with full siblings.

CONCLUSIONS

Children with sibling relatedness other than full siblings entered puberty earlier than their peers with full siblings even after adjustment for parental cohabitation status, childhood body mass index and childhood internalizing and externalizing symptoms.

Maternal thyroid disease in pregnancy and timing of pubertal development in sons and daughters

OBJECTIVE

To study whether maternal thyroid disease in pregnancy is associated with pubertal timing in sons and daughters.

DESIGN

Cohort study.

SETTING

National birth cohort and health registers.

PATIENT(S)

A total of 15,763 mothers and children from the Danish National Birth Cohort and its Puberty Cohort.

INTERVENTION(S)

Register-based and self-reported information on maternal thyroid diseases during pregnancy (hyperthyroidism, hypothyroidism, benign goiter, or no thyroid disease [reference group]).

MAIN OUTCOME MEASURE(S)

The adjusted mean age difference (months) at attaining several self-reported pubertal milestones collected every 6 months using an interval-censored regression and the average difference in age at attaining all pubertal milestones using the Huber-White robust variance estimation (primary outcome).

RESULT(S)

Sons of mothers with hyperthyroidism had earlier pubertal development (average difference, -2.9 [95% confidence interval (CI), -5.0 to -0.7] months) than unexposed sons. Maternal hypothyroidism was not associated with pubertal development in sons (average difference, -1.2 [95% CI, -5.1 to 2.7] months). We observed nonstatistically significant indications of earlier pubertal development in sons of mothers with benign goiter (average difference, -1.9 [95% CI, -4.6 to 0.9] months). Maternal thyroid disease was not associated with pubertal development in daughters (average difference (months), hyperthyroidism, -0.8 [95% CI, -2.8 to 1.2]; hypothyroidism, 0.3 [95% CI, -3.1 to 3.8]; and benign goiter, 0.7 [95% CI, -2.0 to 3.4]).

CONCLUSION(S)

We found indications of earlier pubertal development in sons of mothers with hyperthyroidism. More research is needed to further investigate the observed sex-specific association.

Heterozygosity of the major histocompatibility complex predicts later self-reported pubertal maturation in men

Individual variation in the age of pubertal onset is linked to physical and mental health, yet the factors underlying this variation are poorly understood. Life history theory predicts that individuals at higher risk of mortality due to extrinsic causes such as infectious disease should sexually mature and reproduce earlier, whereas those at lower risk can delay puberty and continue to invest resources in somatic growth. We examined relationships between a genetic predictor of infectious disease resistance, heterozygosity of the major histocompatibility complex (MHC), referred to as the human leukocyte antigen (HLA) gene in humans, and self-reported pubertal timing. In a combined sample of men from Canada (n = 137) and the United States (n = 43), MHC heterozygosity predicted later self-reported pubertal development. These findings suggest a genetic trade-off between immunocompetence and sexual maturation in human males.

The influence of parental age on timing of puberty: A study in the Danish National Birth Cohort

Aims: Concerns have been raised about the potential negative biological effect of postponed parenthood upon the health of subsequent generations, including reproductive health. This study aimed to estimate if high parental age at birth was associated with accelerated pubertal timing in offspring. Methods: In this large-scale cohort study, 15,819 children born by mothers in the Danish National Birth Cohort from 2000 to 2003 participated in a nationwide puberty cohort (participation rate 71%). Between 2012 and 2018, the children reported half-yearly information on pubertal status using web-based questionnaires from 11 years throughout puberty or 18 years of age. Information on parental age was drawn from nationwide registers. We estimated adjusted mean differences in months for age at attaining the pubertal milestones and pubertal timing overall between the pre-specified parental age groups: 20-29 (reference), 30-34 and advanced parental age groups (35-44 years for mothers and >35 years for fathers). Results: Overall, parental age at birth of the child was not associated with pubertal timing in daughters or sons. For sons of older fathers (>35 years), we observed indications towards slightly earlier pubertal timing in the range of 0.3-2.4 months for nearly all pubertal milestones, but all confidence intervals were wide, and many included the null. Conclusions: We found no strong association between parental age and timing of puberty, and we find it unlikely that the decreasing age in pubertal timing is a result of parental decision to delay childbearing.

Recent pubertal timing trends in Northern Taiwanese children: Comparison with skeletal maturity

BACKGROUND

International studies have reported an early age of onset of puberty in girls and boys. However, the current situation of puberty onset in Taiwanese children is unknown. In this study, the timing of menarche and pubertal change in testicular volume (TV) in Taiwanese children was examined, and bone age (BA) was used as an internal somatic maturity scale and compared with the chronological age (CA) at pubertal timing.

METHODS

Clinical data from October 1, 2010, to March 31, 2018, were retrospectively collected from a general hospital in Taipei. The data of patients who were diagnosed with endocrine/genetic disorders were excluded. Clinical data included CA, timing of menarche, and X-ray images of TV and BA. BA was determined by a senior pediatrician and a senior pediatric radiologist. The reliability and validity of BA readings were tested. Collected data were analyzed statistically.

RESULTS

Overall, TV records of 241 boys and the menarche timing data of 98 girls were collected from 1823 children. CA for menarche was 11.35 ± 1.06 years (mean ± SD), and BA for menarche was 12.95 ± 0.80 years. CA and BA at TV = 15 mL in male puberty was 12.32 ± 1.22 and 13.46 ± 0.68 years, respectively. A stronger correlation was observed between TV and BA than between TV and CA during the pubertal period.

CONCLUSION

The secular trend of earlier puberty timing continues. The decline rate of menarche timing was approximately 0.43 years per decade in the past 30 years. Among boys, an advance of more than 1 year in pubertal timing age was observed over the past 20 years. BA and TV showed high correlation during puberty.

Maternal pre-pregnancy obesity and timing of puberty in sons and daughters: a population-based cohort study

Background

In many countries, an increased prevalence of obesity in pregnancy has coincided with a declining pubertal age. We aimed to explore the potential effect of maternal pre-pregnancy overweight and obesity on timing of puberty in sons and daughters.

Methods

Between 2012 and 2018, 15 819 of 22 439 invited children from the Danish National Birth Cohort, born 2000–03, provided half-yearly information from the age of 11 years on the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne and axillary hair. We estimated adjusted mean monthly differences (with 95% confidence intervals) in age at attaining the pubertal milestones for children exposed to maternal pre-pregnancy obesity [body mass index (BMI) ≥30.0 kg/m²] or overweight (BMI 25.0 to 29.9 kg/m²) with normal weight (BMI 18.5 to 24.9 kg/m²) as reference. In mediation analysis, we explored whether childhood BMI at age 7 years mediated the associations.

Results

Maternal pre-pregnancy obesity was associated with earlier age at attaining most pubertal milestones in sons, and pre-pregnancy overweight and obesity were associated with earlier age at attaining all pubertal milestones in daughters. When combining all pubertal milestones, pre-pregnancy obesity [sons: −1.5 (−2.5, −0.4) months; daughters: −3.2 (−4.2, −2.1) months] and overweight [daughters only: −2.6 (−3.3, −1.8) months] were associated with earlier timing of puberty. The associations in sons were completely mediated by higher childhood BMI and partly so in daughters.

Conclusions

Maternal pre-pregnancy obesity appears to lower timing of puberty through childhood obesity in sons and mainly through other mechanisms in daughters.

Systematic Review and Meta-analysis of Testicular Germ Cell Tumors Following In Utero Exposure to Diethylstilbestrol

Background

Early exposure to estrogen-like compounds has been implicated in the etiology of testicular cancer, but individual level epidemiologic data addressing this hypothesis are scarce. The synthetic estrogen diethylstilbestrol (DES) was administered during pregnancy from 1948 to 1971, but sequelae of in utero exposure have been more extensively characterized in females than in males.

Methods

By systematic review, we sought to identify all epidemiologic research relating testicular cancer to a history of in utero exposure to diethylstilbestrol. Identified studies were critically appraised to assemble a set of nonredundant data in which any in utero exposure to DES was compared between men with incident testicular cancer and cancer-free men. These data were synthesized using random effects meta-analysis to estimate the summary association between in utero DES exposure and testicular cancer.

Results

By meta-analysis of data from the six qualifying studies, the summary odds ratio estimate of the in utero DES-testicular cancer association was 2.98 (95% confidence interval = 1.15 to 7.67).

Conclusions

Results of this comprehensive meta-analysis accord with a threefold increase in testicular cancer risk among men who were exposed in utero to DES, implicating early hormonal exposures in etiology of testicular cancer. Because use of DES ceased in 1971, this work may provide the most comprehensive estimate of this association that will be made.

Role of Viral Infections in Testicular Cancer Etiology: Evidence From a Systematic Review and Meta-Analysis

The most represented histotype of testicular cancer is the testicular germ-cell tumor (TGCT), both seminoma and non-seminoma. The pathogenesis of this cancer is poorly known. A possible causal relationship between viral infections and TGCTs was firstly evoked almost 40 years ago and is still a subject of debate. In the recent past, different authors have argued about a possible role of specific viruses in the development of TGCTs including human papillomavirus (HPV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), Parvovirus B-19, and human immunodeficiency virus (HIV). The aim of this present review was to summarize, for each virus considered, the available evidence on the impact of viral infections on the risk of developing TGCTs. The review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included all observational studies reported in English evaluating the correlations between viral infections (HPV, CMV, EBV, Parvovirus B19, and HIV) and TGCTs. The methodological quality of studies included in the meta-analysis was evaluated using a modified version of the "Newcastle-Ottawa Scale." Meta-analyses were conducted using the "Generic inverse variance" method, where a pooled odds ratio (OR) was determined from the natural logarithm (LN) of the studies' individual OR [LN (OR)] and the 95% CI. A total of 20 studies (on 265,057 patients) were included in the review. Meta-analysis showed an association with TGCTs only for some of the explored viruses. In particular, no association was found for HPV, CMV, and Parvovirus B-19 infection (p = ns). Conversely, EBV and HIV infections were significantly associated with higher risk of developing TGCTs (OR 7.38, 95% CI 1.89-28.75, p = 0.004; OR 1.71, 95% CI 1.51-1.93, p < 0.00001). In conclusion, we found adequate evidence supporting an oncogenic effect of HIV and EBV on the human testis. Conversely, available data on HPV and TGCTs risk are conflicting and further studies are needed to draw firm conclusions. Finally, current evidence does not support an effect of CMV and Parvovirus B-19 on testicular carcinogenesis.

Maternal Smoking During Pregnancy and Timing of Puberty in Sons and Daughters: A Population-Based Cohort Study

Because early puberty has been linked to diseases later in life, identification of modifiable causes of early puberty is of interest. We explored the possible associations between maternal smoking during pregnancy and pubertal development in sons and daughters. Between 2012 and 2017, 15,819 children from the Danish National Birth Cohort, born during 2000-2003, provided half-yearly information on puberty from the age of 11 years. We estimated adjusted age differences (in months) at attaining various pubertal milestones, including Tanner stages, per 10 daily cigarettes smoked in the first trimester of gestation. In sons, exposure to smoking in utero was associated with earlier genital development (Tanner 2, -1.3 months, 95% confidence interval (CI): -2.5, 0.0; Tanner 5, -3.7 months, 95% CI: -5.3, -2.0), pubic hair development (Tanner 2, -1.8 months, 95% CI: -2.9, -0.6; Tanner 5, -2.9 months, 95% CI: -4.2, -1.7), and voice break (-2.4 months, 95% CI: -3.6, -1.3). In daughters, maternal smoking was associated with earlier breast development (Tanner 2, -3.4 months, 95% CI: -5.3, -1.5; Tanner 5, -4.7 months, 95% CI: -6.5, -2.9), pubic hair development stages 3-5 (Tanner 5, -2.5 months, 95% CI: -4.1, -1.0), and menarche (-3.1 months, 95% CI: -4.0, -2.3). Fetal exposure to tobacco smoke might advance timing of puberty in boys and girls.

Timing of puberty in boys and girls: A population-based study

BACKGROUND

A secular trend towards earlier puberty has been observed in girls, while a similar trend has been more uncertain in boys. We estimated current ages at pubertal development in both boys and girls.

METHODS

In this population-based cohort study, 14 759 of 22 439 invited boys and girls born from 2000 to 2003 in the Danish National Birth Cohort gave half-yearly self-reported information on puberty from the age of 11.5 years and throughout puberty. This late start of follow-up limits the estimation of age at onset of puberty but not later pubertal milestones. We estimated mean age at attaining the following pubertal milestones in years with 95% confidence intervals (CI): age at menarche, voice break, first ejaculation of semen and Tanner stages for pubic hair development and breast development or genital development. Further, the difference in mean age at menarche between mothers and daughters was estimated.

RESULTS

In boys, voice break occurred at 13.1 (95% CI 13.0, 13.1) years, first ejaculation of semen occurred at 13.4 (95% CI 13.3, 13.4) years, and Tanner Genital Stage 5 occurred at 15.6 (95% CI 15.5, 15.6) years. In girls, age at menarche occurred at 13.0 (95% CI 13.0, 13.1) years and Tanner Breast Stage 5 occurred at 15.8 (95% CI 15.7, 15.9) years. Daughters had menarche 3.6 (95% CI 3.1, 4.2) months earlier than their mothers had.

CONCLUSION

These data indicate that age at menarche has declined and to some extent support a decline in age at attaining other markers of pubertal development among boys.

Acetaminophen (Paracetamol) Exposure During Pregnancy and Pubertal Development in Boys and Girls From a Nationwide Puberty Cohort

This study explored the association between exposure to acetaminophen during pregnancy and pubertal development using data from 15,822 boys and girls in the longitudinal Puberty Cohort, nested within the Danish National Birth Cohort. Use of acetaminophen was reported 3 times during pregnancy and 6 months postpartum. In total, 54% of mothers indicated use at least once during pregnancy. Between 2012 and 2017, sons and daughters provided information on a wide range of pubertal milestones-including Tanner stages, axillary hair growth, and age at menarche or voice break and first ejaculation-every 6 months from 11 years of age until full sexual maturation. Data were analyzed using a regression model for interval-censored data, providing adjusted mean monthly differences in age at attaining the pubertal milestones according to intrauterine cumulative (weeks) and trimester-specific acetaminophen exposure. Our results suggested a tendency towards slightly earlier attainment of almost all studied markers of female pubertal development with increasing number of weeks of exposure (i.e., about 1.5-3 months earlier age at pubic hair, axillary hair, and acne development comparing unexposed with those prenatally exposed for more than 12 weeks). Male pubertal development had no strong association with acetaminophen exposure.

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

Objectives

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

Materials and methods

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

Results

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

Conclusions

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

Is age at puberty associated with semen quality and reproductive hormones in young adult life?

The evidence is scarce on the association between age at puberty and semen quality. A cohort of 320 Danish men aged 18-21 years enrolled in the "Healthy Habits for Two" birth cohort provided self-reported data on pubertal indicators and delivered semen and blood samples. The results indicated an association between older age at pubertal development and lower semen quality and altered reproductive hormones concentrations as measured in young adult life. Men who had their first nocturnal emission, start of pubic hair growth and first voice break episode when older than 15 years had 37.0%, 45.0% and 32.7% lower sperm concentration; 37.8%, 44.2% and 29.1% lower total sperm count; 7.4%, 13.4% and 15.3% lower testosterone concentration; and 21.3%, 1.5% and 3.7% lower inhibin B concentration, respectively, compared with the men who were younger than 13 years at their first pubertal indicators. Only few of the results were statistically significant, but similar tendencies were seen in several of the reproductive parameters suggesting an association between the timing of pubertal development and reproductive health later in life.

Aging with a traumatic brain injury: Could behavioral morbidities and endocrine symptoms be influenced by microglial priming?

A myriad of factors influence the developmental and aging process and impact health and life span. Mounting evidence indicates that brain injury, even moderate injury, can lead to lifetime of physical and mental health symptoms. Therefore, the purpose of this mini-review is to discuss how recovery from traumatic brain injury (TBI) depends on age-at-injury and how aging with a TBI affects long-term recovery. TBI initiates pathophysiological processes that dismantle circuits in the brain. In response, reparative and restorative processes reorganize circuits to overcome the injury-induced damage. The extent of circuit dismantling and subsequent reorganization depends as much on the initial injury parameters as other contributing factors, such as genetics and age. Age-at-injury influences the way the brain is able to repair itself, as a result of developmental status, extent of cellular senescence, and injury-induced inflammation. Moreover, endocrine dysfunction can occur with TBI. Depending on the age of the individual at the time of injury, endocrine dysfunction may disrupt growth, puberty, influence social behaviors, and possibly alter the inflammatory response. In turn, activation of microglia, the brain's immune cells, after injury may continue to fuel endocrine dysfunction. With age, the immune system develops and microglia become primed to subsequent challenges. Sustained inflammation and microglial activation can continue for weeks to months post-injury. This prolonged inflammation can influence developmental processes, behavioral performance and age-related decline. Overall, brain injury may influence the aging process and expedite glial and neuronal alterations that impact mental health.

Epidemiological Studies and Effects of Environmental Estrogens

Increases in cancer of the testis, breast, and prostate have been noted recently, and these increases have often been attributed to a ubiquitous exposure to endocrine-modulating substances. In an effort to either prove or refute these associations, morbidities of (and mortalities from) certain hormonally responsive organs are reviewed. Cancer of the breast, ovary, uterus, cervix, prostate, and testis were selected for comparison and analysis of trends in incidence and mortality. The incidences of cryptorchidism and hypospadias were selected as birth defects representative of possible effects from in utero exposure to excessive estrogens. Sperm counts and endom etriosis were selected as other possible indicators of environmental estrogen effects. Wide, sometimes orders of magnitude, variability exists between incidences in some indicators between different geographical areas and between ethnic groups. Some explanations unrelated to environmental exposures are apparent, and some observations contradict a universal exposure to the same endocrine-modulating substance. In addition, wide differences in incidences exist among virtually adjacent geographical areas and between ethnic groups living in the same geographic area. The data available at present do not lead to the conclusion that endocrine-modulating substances account for worldwide trends in these epidem iological studies.

Etiology and early pathogenesis of malignant testicular germ cell tumors: towards possibilities for preinvasive diagnosis

Malignant testicular germ cell tumors (TGCT) are the most frequent cancers in Caucasian males (20-40 years) with an 70% increasing incidence the last 20 years, probably due to combined action of (epi)genetic and (micro)environmental factors. It is expected that TGCT have carcinoma in situ(CIS) as their common precursor, originating from an embryonic germ cell blocked in its maturation process. The overall cure rate of TGCT is more than 90%, however, men surviving TGCT can present long-term side effects of systemic cancer treatment. In contrast, men diagnosed and treated for CIS only continue to live without these long-term side effects. Therefore, early detection of CIS has great health benefits, which will require an informative screening method. This review described the etiology and early pathogenesis of TGCT, as well as the possibilities of early detection and future potential of screening men at risk for TGCT. For screening, a well-defined risk profile based on both genetic and environmental risk factors is needed. Since 2009, several genome wide association studies (GWAS) have been published, reporting on single-nucleotide polymorphisms (SNPs) with significant associations in or near the genes KITLG, SPRY4, BAK1, DMRT1, TERT, ATF7IP, HPGDS, MAD1L1, RFWD3, TEX14, and PPM1E, likely to be related to TGCT development. Prenatal, perinatal, and postnatal environmental factors also influence the onset of CIS. A noninvasive early detection method for CIS would be highly beneficial in a clinical setting, for which specific miRNA detection in semen seems to be very promising. Further research is needed to develop a well-defined TGCT risk profile, based on gene-environment interactions, combined with noninvasive detection method for CIS.

Nontesticular cancers in relatives of testicular germ cell tumor (TGCT) patients from multiple-case TGCT families

Testicular germ cell tumors (TGCT) exhibit striking familial aggregation that remains incompletely explained. To improve the phenotypic definition of familial TGCT (FTGCT), we studied an international cohort of multiple-case TGCT families to determine whether first-degree relatives of FTGCT cases are at increased risk of other types of cancer. We identified 1041 first-degree relatives of TGCT cases in 66 multiple-case TGCT families from Norway and 64 from the United States (combined follow-up of 31,556 person-years). We collected data on all cancers (except nonmelanoma skin cancers) reported by the family informant in these relatives, and we attempted to verify all reported cancer diagnoses through medical or cancer registry records. We calculated observed-to-expected (O/E) standardized incidence ratios, together with 95% confidence intervals (CI), for invasive cancers other than TGCT. We found no increase in risk of cancer overall (Norway O/E = 0.8; 95% CI: 0.6–1.1 and United States O/E = 0.9; 95% CI: 0.7–1.3). Site-specific analyses pooled across the two countries revealed a leukemia excess (O/E = 6.5; 95% CI: 3.0–12.3), deficit of female breast cancer (O/E = 0.0; 95% CI: 0.0–0.6) and increased risk of soft tissue sarcoma (O/E = 7.2; 95% CI: 2.0–18.4); in all instances, these results were based on small case numbers and statistically significant only in Norway. While limited by sample size and potential issues relating to completeness of cancer reporting, this study in multiple-case TGCT families does not support the hypothesis that cancers other than testis cancer contribute to the FTGCT phenotype.

Diethylstilboestrol exposure does not reduce testosterone production in human fetal testis xenografts

In rodents, in utero exposure to exogenous estrogens including diethylstilboestrol (DES) results in major suppression of steroidogenesis in fetal testes. Whether similar effects occur in the human fetal testis is equivocal. Based on the results of the rodent studies, we hypothesised that exposure of human fetal testes to DES would result in a reduction in testosterone production. We show, using a xenograft approach, that testosterone production is not reduced in human fetal testis following DES exposure. Human fetal testes (15–19 weeks’ gestation, n = 6) were xenografted into castrate male nude mice which were then treated for 35 days with vehicle or 100 µg/kg DES three times a week. For comparison, similar treatment was applied to pregnant rats from e13.5–e20.5 and effects on fetal testes evaluated at e21.5. Xenograft testosterone production was assessed by measuring host seminal vesicle (SV) weights as an indirect measure over the entire grafting period, and single measurement of serum testosterone at termination. Human fetal testis xenografts showed similar survival in DES and vehicle-exposed hosts. SV weight (44.3 v 26.6 mg, p = 0.01) was significantly increased in DES compared to vehicle-exposed hosts, respectively, indicating an overall increase in xenograft testosterone production over the grafting period, whilst serum testosterone at termination was unchanged. In contrast intra-testicular testosterone levels were reduced by 89%, in fetal rats exposed to DES. In rats, DES effects are mediated via Estrogen Receptor α (ESR1). We determined ESR1 protein and mRNA expression in human and rat fetal testis. ESR1 was expressed in rat, but not in human, fetal Leydig cells. We conclude that human fetal testis exposure to DES does not impair testosterone production as it does in rats, probably because ESR1 is not expressed in human fetal Leydig cells. This indicates that DES exposure is likely to pose minimal risk to masculinization of the human fetus.

Maternal cigarette smoking during pregnancy and pubertal development in sons. A follow-up study of a birth cohort

Epidemiological studies have raised concern about the reproductive consequences of prenatal cigarette smoking exposure, possibly affecting semen quality and onset of pubertal development of the offspring. The aim of this study was to further investigate pubertal development in young men exposed to cigarette smoking in foetal life. In a Danish pregnancy cohort, information on maternal smoking during pregnancy was available from questionnaires administered in 1984-1987, and information on pubertal development, assessed by age at first nocturnal emission, acne, voice break and regular shaving, was obtained from a follow-up questionnaire administered in 2005 to the young men (age: 18-21). We found no significant association between prenatal cigarette smoking exposure and earlier onset of puberty, but we did observe a tendency towards earlier age of first nocturnal emission, acne and voice break, indicating an accelerated age of pubertal development. Men exposed to ≥15 cigarettes/day had 3.1 months (95% CI: -6.4; 0.2) earlier age at acne and 2.2 months (95% CI: -7.3; 3.0) earlier age at first nocturnal emission, 1.2 months (95% CI: -4.6; 2.2) earlier age at voice break, however, 1.3 months (95% CI: -1.6; 4.3) later age at regular shaving, compared with unexposed men. Prenatal cigarette smoking exposure may induce an earlier age at onset of puberty in young men, but larger studies with prospectively collected data on pubertal development are needed to explore this hypothesis further.

Age at puberty and risk of testicular cancer: a meta-analysis

Testicular cancer is one of the most rapidly increasing tumour types but its aetiology is still largely unexplained. Cryptorchidism and familial testicular cancer, established risk factors, explain less than 10% of all cases. Among investigated post-natal factors, early puberty was suggested as a potential risk factor but the topic has been poorly investigated. We undertook a meta-analysis of the effect of age at puberty on testicular cancer risk, attempting at enhancing the homogeneity in the definition of the exposure among studies to obtain valid pooled estimates. Search strategies were conducted in PubMed on December 2011. All markers of puberty onset (age at voice change, age when started shaving and reported age at onset) were considered. We re-categorized age at puberty from all studies into a common three-level variable: younger than peers, same age as peers, older than peers. A total of 391 references were retrieved, of which 12 met the inclusion criteria. Later puberty appeared to be protective. In particular late vs. same age at start shaving gave an OR of 0.84 (95% CI: 0.75-0.95, five studies); late vs. same age at voice change gave an OR of 0.87 (95% CI: 0.75-1.01, five studies); and later age than peers at reported onset of puberty gave an OR of 0.81 (95% CI: 0.73-0.89, eight studies). Early puberty showed no effect on testicular cancer risk. This meta-analysis has found consistent evidence of a decreased risk of testicular cancer in association with later puberty, suggesting that post-natal factors may contribute to testicular cancer risk.

Childhood infections, orchitis and testicular germ cell tumours: a report from the STEED study and a meta-analysis of existing data

Background:

Similarities between the age-specific incidence pattern of testicular germ cell tumours (TGCTs) and the age-specific incidence pattern of cancers of viral origin prompted us to evaluate the relationship between common infections occurring during childhood or young adult life and TGCT using existing data from the US Servicemen's Testicular Tumor Environmental and Endocrine Determinants (STEED) case–control study.

Methods:

TGCT cases diagnosed between 2002 and 2005 (n=767) were matched on age, race and serum draw date to at least one control (n=929).

Results:

None of the infections evaluated were associated with TGCT risk. Further, a meta-analysis of mumps and mumps orchitis or orchitis infection did not support an association with TGCT (mumps pooled odds ratio (OR): 1.03, 95% confidence interval (CI): 0.89–1.20; mumps orchitis or orchitis pooled OR: 1.80, 95% CI: 0.74–4.42).

Conclusion:

Based on our evaluation of childhood and early life infections and meta-analyses of mumps and mumps orchitis and/or orchitis, TGCT does not appear to be associated with common childhood infections.

Cryptorchidism and testicular germ cell tumors: comprehensive meta-analysis reveals that association between these conditions diminished over time and is modified by clinical characteristics

INTRODUCTION

Risk of testicular germ cell tumors (TGCT) is consistently associated with a history of cryptorchidism (CO) in epidemiologic studies. Factors modifying the association may provide insights regarding etiology of TGCT and suggest a basis for individualized care of CO. To identify modifiers of the CO-TGCT association, we conducted a comprehensive, quantitative evaluation of epidemiologic data.

MATERIALS AND METHODS

Human studies cited in PubMed or ISI Web of Science indices through December 2011 and selected unpublished epidemiologic data were reviewed to identify 35 articles and one unpublished dataset with high-quality data on the CO-TGCT association. Association data were extracted as point and 95% confidence interval estimates of odds ratio (OR) or standardized incidence ratio (SIR), or as tabulated data. Values were recorded for each study population, and for subgroups defined by features of study design, CO and TGCT. Extracted data were used to estimate summary risk ratios (sRR) and evaluate heterogeneity of the CO-TGCT association between subgroups.

RESULTS

The overall meta-analysis showed that history of CO is associated with four-fold increased TGCT risk [RR = 4.1(95% CI = 3.6-4.7)]. Subgroup analyses identified five determinants of stronger association: bilateral CO, unilateral CO ipsilateral to TGCT, delayed CO treatment, TGCT diagnosed before 1970, and seminoma histology.

CONCLUSIONS

Modifying factors may provide insight into TGCT etiology and suggest improved approaches to managing CO. Based on available data, CO patients and their parents or caregivers should be made aware of elevated TGCT risk following orchidopexy, regardless of age at repair, unilateral vs. bilateral non-descent, or position of undescended testes.

Retroperitoneal lymph node dissection for metastatic germ cell tumours

INTRODUCTION

In the North Trent Cancer network (NTCN) patients requiring retroperitoneal lymphadenectomy for metastatic testicular cancer have been treated by vascular service since 1990. This paper reviews our experience and considers the case for involvement of vascular surgeons in the management of these tumours.

PATIENTS AND METHODS

Patients referred by the NTCN to the vascular service for retroperitoneal lymphadenectomy between 1990 and 2009 were identified through a germ cell database. Data were supplemented by a review of case notes to record histology, intraoperative and postoperative details.

RESULTS

A total of 64 patients were referred to the vascular service for retroperitoneal lymph node dissection, with a median age of 29 years (16-63 years) and a median follow-up of 4.9 years. Ten patients died: eight from tumour recurrence, one from septicaemia during chemotherapy and one by suicide. Of the 54 who survived, 7 were alive with residual masses and 47 patients were disease-free at the last follow-up. Sixteen patients required vascular procedures: four had aortic repair (fascia), three had aortic replacement (spiral graft), four had inferior vena cava resection, two had iliac artery replacement and two had iliac vein resection.

CONCLUSIONS

Retroperitoneal lymph node dissection often involves mobilisation and/or the resection/replacement of major vessels. We recommend that a vascular surgeon should be a part of testicular germ cell multidisciplinary team.

A systematic review and meta-analysis of perinatal variables in relation to the risk of testicular cancer--experiences of the son

BACKGROUND

We undertook a systematic review and meta-analysis of perinatal variables in relation to testicular cancer risk, with a specific focus upon characteristics of the son.

METHODS

Literature databases Scopus, EMBASE, PubMed and Web of Science were searched using highly sensitive search strategies. Of 5865 references retrieved, 67 articles met the inclusion criteria, each of which was included in at least one perinatal analysis.

RESULTS

Random effects meta-analysis produced the following results for association with testicular cancer risk: birth weight [per kilogram, odds ratio (OR) = 0.94, 95% confidence interval (CI) 0.88-1.01, I(2)= 12%], low birth weight (OR = 1.34, 95% CI 1.08-1.67, I(2)= 51%), high birth weight (OR = 1.05, 95% CI 0.96-1.14, I(2)= 0%), gestational age (per week, OR = 0.95, 95% CI 0.92-0.98, I(2)= 38%; low vs not, OR = 1.31, 95% CI 1.07-1.59, I(2)= 49%), cryptorchidism (OR = 4.30, 95% CI 3.62-5.11, I(2)= 44%), inguinal hernia (OR = 1.63, 95% CI 1.37-1.94, I(2)= 38%) and twinning (OR = 1.22, 95% CI 1.03-1.44, I(2)= 22%). Meta-analyses of the variables birth length, breastfeeding and neonatal jaundice did not provide evidence for an association with testicular cancer risk. When low birth weight was stratified by data ascertainment (record/registry vs self-report), only the category of self-report was indicative of an association. Meta-regression of data ascertainment (record/registry vs self-report) inferred that record-/registry-based studies were less supportive of an association with gestational age (per week = 0.97, 95% CI 0.94-1.00, I(2)( )= 29%; low vs not = 1.08, 95% CI 0.91-1.28, I(2)= 32%).

CONCLUSION

In conclusion, this systematic review and meta-analysis finds evidence that cryptorchidism, inguinal hernia and twinning, and tentative evidence that birth weight and gestational age, are associated with risk of testicular cancer.

Maternal body mass index and risk of testicular cancer in male offspring: a systematic review and meta-analysis

OBJECTIVES

To date a number of studies have examined the association between maternal weight and testicular cancer risk although results have been largely inconsistent. This systematic review and meta-analysis investigated the nature of this association.

METHODS

Search strategies were conducted in Ovid Medline (1950-2009), Embase (1980-2009), Web of Science (1970-2009), and CINAHL (1937-2009) using keywords for maternal weight (BMI) and testicular cancer.

RESULTS

The literature search produced 1689 hits from which 63 papers were extracted. Only 7 studies met the pre-defined criteria. Random effects meta-analyses were conducted. The combined unadjusted OR (95% CI) of testicular cancer in the highest reported category of maternal BMI compared with the moderate maternal BMI was 0.82 (0.65-1.02). The Cochran's Q P value was 0.82 and the corresponding I(2) was 0%, both indicating very little variability among studies. The combined unadjusted OR (95% CI) for testicular cancer risk in the lowest reported category of maternal BMI compared to a moderate maternal BMI category was 0.88 (0.65-1.20). The Cochran's Q P value was 0.05 and the corresponding I(2) was 54%, indicating evidence of statistical heterogeneity. The combined unadjusted OR (95% CI) of testicular cancer risk per unit increase in maternal BMI was 1.01 (0.97-1.06). The Cochran's Q test had a P value of 0.05 and the corresponding I(2) was 55% indicating evidence of statistical heterogeneity.

CONCLUSION

This meta-analysis, which included a small number of studies, showed that a higher maternal weight does not increase the risk of testicular cancer in male offspring. Though an inverse association between high maternal BMI and testicular cancer risk was detected, it was not statistically significant. Further primary studies with adjustment for appropriate confounders are required.

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.

Gender-specific differences in birthweight and the odds of puberty: NHANES III, 1988-94

The association between birthweight and the odds ratio (OR) of pubertal status in girls aged between 8 and 11 and in boys aged between 8 and 12 was examined using the 1988-94 Third National Health and Nutrition Examination Survey (NHANES III). Girls (n = 956), and boys (n = 1199), who had data on birthweight and Tanner staging were included. Maternal-reported birthweight, smoking in pregnancy and other information were provided in a home interview, while Tanner staging to assess pubertal status was part of a medical examination. Multiple logistic regression models were computed for the endpoints of the OR [95% confidence interval (CI)] of being Tanner Stage 2+ vs. 1 or being 2+ vs. 1 in an asynchronous pubertal pathway after adjustment for the complex sampling design of NHANES, age, race, height and body mass index (BMI). Birthweight was not associated with the OR of Tanner stage 2+ among girls; however, boys who were low birthweight (<2500 g) and boys born higher than average birthweight (3500-3999 g) were more likely to be Tanner stage 2+ than 1. Childhood BMI was associated with the OR of having entered puberty among girls, but not boys. In an analysis of asynchronous maturation, girls born at high birthweight (>4000 g) were more likely to have breast development 3+ than girls of normal birthweight, OR = 3.18 [95% CI 1.39, 8.25]. Thus, the birthweight-puberty association varies by gender and by pubertal pathway. Our findings need replication in prospective longitudinal studies, and research to understand the mechanisms underlying the relation of early life exposures to cancer risk.

Endogenous DNA damage and testicular germ cell tumors

Testicular germ cell tumors are comprised of two histologic groups, seminomas and non-seminomas. We postulated that the possible divergent pathogeneses of these histologies may be partially explained by variable levels of net endogenous DNA damage. To test our hypothesis, we conducted a case-case analysis of 51 seminoma and 61 non-seminoma patients using data and specimens from the Familial Testicular Cancer study and the U.S. Radiologic Technologists cohort. A lymphoblastoid cell line was cultured for each patient and the alkaline comet assay was used to determine four parameters: tail DNA, tail length, comet distributed moment (CDM) and Olive tail moment (OTM). Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using logistic regression. Values for tail length, tail DNA, CDM and OTM were modelled as categorical variables using the 50th and 75th percentiles of the seminoma group. Tail DNA was significantly associated with non-seminoma compared with seminoma (OR(50th percentile) = 3.31, 95% CI: 1.00, 10.98; OR(75th percentile) = 3.71, 95% CI: 1.04, 13.20; p for trend = 0.039). OTM exhibited similar, albeit statistically non-significant, risk estimates (OR(50th percentile) = 2.27, 95% CI: 0.75, 6.87; OR(75th percentile) = 2.40, 95% CI: 0.75, 7.71; p for trend = 0.12) whereas tail length and CDM showed no association. In conclusion, the results for tail DNA and OTM indicate that net endogenous levels are higher in patients who develop non-seminoma compared with seminoma. This may partly explain the more aggressive biology and younger age-of-onset of this histologic subgroup compared with the relatively less aggressive, later-onset seminoma.

Etiologic factors in testicular germ-cell tumors

Globally, testicular cancer incidence is highest among men of northern European ancestry and lowest among men of Asian and African descent. Incidence rates have been increasing around the world for at least 50 years, but mortality rates, at least in developed countries, have been declining. While reasons for the decreases in mortality are related to improvements in therapeutic regimens introduced in the late 1970s, reasons for the increase in incidence are less well understood. However, an accumulating body of evidence suggests that testicular cancer arises in fetal life. Perinatal factors, including exposure to endocrine-disrupting chemicals, have been suggested to be related to risk.

Family history of cancer and malignant germ cell tumors in children: a report from the Children's Oncology Group

Family history of testicular cancer is an established risk factor for adult testicular germ cell tumors (GCT). We evaluated the association between family history of cancer and pediatric GCT in a Children's Oncology Group case-control study that included 274 GCT cases (195 female and 79 male) diagnosed < age 15 years and 418 controls frequency matched to cases on sex and age. Family history data were collected through telephone interviews with biological mothers and fathers and unconditional logistic regression was used to evaluate associations with GCT adjusting for potential confounders. A family history of cancer with onset < age 40 years was associated with a reduced risk of GCT among female cases (Odds Ratio (OR) = 0.50, 95% Confidence Interval (CI) 0.28-0.89) and an increased risk among male cases (OR = 2.56, 95% CI 1.02-6.44). Male cases were more likely to report family history of melanoma compared with male controls (OR = 4.65, 95% CI 1.40-15.4). There was an inverse association between family history of ovarian or uterine cancers and GCT in girls (OR = 0.46, 95% CI 0.22-0.96). These sex and cancer site specific associations should be confirmed in additional studies as they may provide clues to the etiology of pediatric GCT.

A systematic review and meta-analysis of perinatal variables in relation to the risk of testicular cancer--experiences of the mother

BACKGROUND

We undertook a systematic review and meta-analysis of perinatal variables in relation to testicular cancer risk, with a specific focus upon characteristics of the mother.

METHODS

EMBASE, PubMed, Scopus and Web of Science databases were searched using sensitive search strategies. Meta-analysis was undertaken using STATA 10.

RESULTS

A total of 5865 references were retrieved, of which 67 met the inclusion criteria and contributed data to at least one perinatal analysis. Random effects meta-analysis found maternal bleeding during pregnancy [odds ratio (OR) 1.33, 95% confidence interval (CI) 1.02-1.73], birth order (primiparous vs not, 1.08, 95% CI 1.01-1.16; second vs first, OR 0.94, 95% CI 0.88-0.99; third vs first, OR 0.91, 95% CI 0.83-1.01; fourth vs first, OR 0.80, 95% CI 0.69-0.94) and sibship size (2 vs 1, OR 0.93, 95% CI 0.75-1.15; 3 vs 1, OR 0.89, 95% CI 0.74-1.07; 4 vs 1, OR 0.75, 95% CI 0.62-0.90) to be associated with testicular cancer risk. Meta-analyses that produced summary estimates which indicated no association included maternal age, maternal nausea, maternal hypertension, pre-eclampsia, breech delivery and caesarean section. Meta-regression provided evidence that continent of study is important in the relationship between caesarean section and testicular cancer (P = 0.035), and a meta-analysis restricted to the three studies from the USA was suggestive of association (OR 1.67, 95% CI 1.07-2.56).

CONCLUSIONS

This systematic review and meta-analysis has found evidence for associations of maternal bleeding, birth order, sibship size and possibly caesarean section with risk of testicular cancer.

Testicular dysgenesis syndrome and the estrogen hypothesis: a quantitative meta-analysis

Male reproductive tract abnormalities such as hypospadias and cryptorchidism, and testicular cancer have been proposed to comprise a common syndrome together with impaired spermatogenesis with a common etiology resulting from the disruption of gonadal development during fetal life, the testicular dysgenesis syndrome (TDS). The only quantitative summary estimate of the link between prenatal exposure to estrogenic agents and testicular cancer was published over 10 years ago; other reviews of the link between estrogenic compounds, other than the potent pharmaceutical estrogen diethylstilbestrol (DES), and TDS end points have remained inconclusive. We conducted a quantitative meta-analysis of the association between the end points related to TDS and prenatal exposure to estrogenic agents. Inclusion in this analysis was based on mechanistic criteria, and the plausibility of an estrogen receptor (ER)-alpha-mediated mode of action was specifically explored. Eight studies were included, investigating the etiology of hypospadias and/or cryptorchidism that had not been identified in previous systematic reviews. Four additional studies of pharmaceutical estrogens yielded a statistically significant updated summary estimate for testicular cancer. Results of the subset analyses point to the existence of unidentified sources of heterogeneity between studies or within the study population.

Risk of cancer in first- and second-degree relatives of testicular germ cell tumor cases and controls

Risk factors for testicular germ cell tumors (TGCT) have not been well identified; however, data suggest that risks of cancer in family members of men with TGCT is elevated. Using family history data from 738 cases and 904 controls enrolled in the U.S. Servicemen's Testicular Tumor Environmental and Endocrine Determinants (STEED) Study from 2002 to 2005, the risk of cancer in first- and second-degree family members of these men was examined. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models, adjusting for reference age of case or control, race/ethnicity of case or control, sex of family member and lineage (maternal vs. paternal). An increased risk of all cancer among first-degree relatives of cases compared to controls was observed (RR = 1.17, 95% CI: 1.01-1.35). There were suggestions of differences in risk when stratifying all relatives by lineage. For maternal relatives, there was a statistically significant increased risk of all cancer (RR = 1.16, 95% CI: 1.04-1.30), digestive tract (RR = 1.52, 95% CI: 1.15-2.00) and male genital organ cancer (RR = 1.70, 95% CI: 1.15-2.51); there was also a suggestion of increased risks of hematopoetic cancers, cancers in the female genital organs and nonmelanoma skin cancer. For paternal relatives, there was a statistically significant association only with decreased risk of lung cancer (RR = 0.69, 95% CI: 0.51-0.94). Thus, this study suggests that there may be aggregation of cancer among families of men diagnosed with TGCT.

Methyltertiary-Butyl Ether: Studies for Potential Human Health Hazards

When methyl tertiary-butyl ether (MTBE) in gasoline was first introduced to reduce vehicle exhaust emissions and comply with the Clean Air Act, in the United States, a pattern of complaints emerged characterised by seven "key symptoms." Later, carefully controlled volunteer studies did not confirm the existence of the specific key symptoms, although one study of self-reported sensitive (SRS) people did suggest that a threshold at about 11-15% MTBE in gasoline may exist for SRSs in total symptom scores. Neurobehavioral and psychophysiological studies on volunteers, including SRSs, found no adverse responses associated with MTBE at likely exposure levels. MTBE is well and rapidly absorbed following oral and inhalation exposures. Cmax values for MTBE are achieved almost immediately after oral dosing and within 2 h of continuous inhalation. It is rapidly eliminated, either by exhalation as unchanged MTBE or by urinary excretion of its less volatile metabolites. Metabolism is more rapid humans than in rats, for both MTBE and tert-butyl alcohol (TBA), its more persistent primary metabolite. The other primary metabolite, formaldehyde, is detoxified at a rate very much greater than its formation from MTBE. MTBE has no specific effects on reproduction or development, or on genetic material. Neurological effects were observed only at very high concentrations. In carcinogenicity studies of MTBE, TBA, and methanol (included as an endogenous precursor of formaldehyde, without the presence of TBA), some increases in tumor incidence have been observed, but consistency of outcome was lacking and even some degree of replication was observed in only three cases, none of which had human relevance: alpha(2u)-globulin nephropathy-related renal tubule cell adenoma in male rats; Leydig-cell adenoma in male rats, but not in mice, which provide the better model of the human disease; and B-cell-derived lymphoma/leukemia of doubtful pathogenesis that arose mainly in lungs of orally dosed female rats. In addition, hepatocellular adenomas were significantly higher in female CD-1 mice and thyroid follicular-cell adenomas were increased in female B6C3F1 mice treated with TBA, but these results lack any independent confirmation, which would have been possible from a number of other studies.

Perinatal factors and the risk of testicular germ cell tumors

Testicular germ cell tumors (TGCT) are the most common cancer among young men in the United States and Western Europe. Prior evidence suggests that TGCT may arise in perinatal life, although few risk factors have yet been identified. To study the etiology of TGCT, the US Servicemen's Testicular Tumor Environmental and Endocrine Determinants (STEED) case-control study enrolled participants and their mothers between 2002 and 2005. Five hundred twenty-seven mothers of cases and 561 mothers of controls provided information on perinatal variables. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95%CI) associated with the candidate risk factors. Analyses were conducted for all TGCT together and for each histologic subgroup (seminoma and nonseminoma) separately. Young maternal age (<20 vs. 20-29 years, OR = 1.51, 95%CI: 1.09-2.10), young paternal age (<25 vs. 25-29 years, OR = 1.45, 95%CI: 1.08-1.94), maternal parity (3 vs. 1, OR = 0.63, 95%CI: 0.44-0.90) and breech birth (OR = 1.92, 95%CI: 1.03-3.56) were associated with risk of TGCT. For seminoma, young maternal age (<20 vs. 20-29 years, OR = 1.67, 95%CI: 1.10-2.54), young paternal age (<25 vs. 25-29 years, OR = 1.53, 95%CI: 1.03-2.27), maternal parity (3 vs. 1, OR = 0.58, 95%CI: 0.35-0.96) and low birth weight (<2,500 g vs. 2,500-4,000 g, OR = 1.82, 95%CI: 1.00-3.30) were risk factors. Nonseminoma was associated with breech birth (OR = 2.44, 95%CI: 1.25-4.78) and Cesarean section (OR = 2.10, 95%CI: 1.25-3.54). These results support the hypothesis that TGCT may originate in very early life.

Testicular cancer and hormonally active agents

Testicular cancer (TC) is a rare form of cancer, accounting for 1% of all new cancer cases in Canadian males. TC is the most common malignancy among young men, aged 25-34 yr old. Over previous decades, the incidence of TC has increased in many Western countries. Countries with a sufficiently long period of cancer registration, such as Denmark, document this trend back to the first half of the 20th century. The etiology of TC remains poorly understood. Most of the established risk factors are likely related to in utero events, including some factors that are purported to be surrogate measures for exposure to endogenous estrogens. The correlation of TC with other testicular abnormalities and with pregnancy factors led to the proposal that these conditions are a constellation of sequelae of impairment of testicular development called testis dysgenesis syndrome. There is some limited evidence suggesting that exposure to pharmacological estrogens may contribute to some cases of TC. There is currently no compelling evidence that exposure to environmental estrogenic or other hormonally active substances is contributing to the rise in TC incidence observed in Western nations over the last several decades; however, this question has not been extensively studied. The (1) rarity of this condition in the population, (2) long lag time between the presumed sensitive period during fetal development and clinical appearance of the condition, and (3) lack of a good animal model to study the progression of the disease have greatly hindered the understanding of environmental influences on TC risk.

Testicular dysgenesis syndrome and the estrogen hypothesis: a quantitative meta-analysis

BACKGROUND

Male reproductive tract abnormalities such as hypospadias and cryptorchidism, and testicular cancer have been proposed to comprise a common syndrome together with impaired spermatogenesis with a common etiology resulting from the disruption of gonadal development during fetal life, the testicular dysgenesis syndrome (TDS). The hypothesis that in utero exposure to estrogenic agents could induce these disorders was first proposed in 1993. The only quantitative summary estimate of the association between prenatal exposure to estrogenic agents and testicular cancer was published over 10 years ago, and other systematic reviews of the association between estrogenic compounds, other than the potent pharmaceutical estrogen diethylstilbestrol (DES), and TDS end points have remained inconclusive.

OBJECTIVES

We conducted a quantitative meta-analysis of the association between the end points related to TDS and prenatal exposure to estrogenic agents. Inclusion in this analysis was based on mechanistic criteria, and the plausibility of an estrogen receptor (ER)-alpha-mediated mode of action was specifically explored.

RESULTS

We included in this meta-analysis eight studies investigating the etiology of hypospadias and/or cryptorchidism that had not been identified in previous systematic reviews. Four additional studies of pharmaceutical estrogens yielded a statistically significant updated summary estimate for testicular cancer.

CONCLUSIONS

The doubling of the risk ratios for all three end points investigated after DES exposure is consistent with a shared etiology and the TDS hypothesis but does not constitute evidence of an estrogenic mode of action. Results of the subset analyses point to the existence of unidentified sources of heterogeneity between studies or within the study population.

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.

Genetic and environmental risk factors for testicular cancer

Germ-cell testicular cancer has a well-characterized descriptive epidemiology, whereas the aetiology remains largely unknown. It is believed that exposures acting prenatally are instrumental to germ-cell cancer development, although no specific exposure has been identified. Several epidemiological studies have investigated a number of indicators of prenatal exposures, such as birth order, gestational duration, birth weight, maternal age and nausea during pregnancy, but results are inconsistent. This paper briefly reviews the current support for genetic and environmental factors in testicular cancer aetiology. In particular, we have summarized the evidence suggesting a strong role of inherited susceptibility, which is probably carried by the effect of several unknown moderate-risk genes. We have illustrated inconsistencies in the previous studies on prenatal factors by estimating the heterogeneity and pooled odds ratios among twelve studies investigating the association between low birth weight and testicular cancer. We have discussed the possibility that puberty is another time window during which environmental factors may increase the risk of testicular cancer. Finally, we have reviewed the results from studies on cryptorchidism and impaired fertility in relation to risk for testicular cancer. In conclusion, we propose that future aetiological studies on testicular cancer should take postnatal exposures acting during puberty into account and, whenever possible, investigate both main effects and interactions among prenatal factors, genetic factors and postnatal factors.

Birth weight and the risk of testicular cancer: A meta-analysis

The high incidence of testicular cancer in young males indicates a potential role of events during early life. Birth weight has been identified as a factor possibly associated with the risk of cancers later in life. To investigate the association between birth weight and testicular cancer, we conducted a Systematic Review and Meta-Analysis of published studies investigating the association between birth weight and testicular cancer. Data were combined using a fixed-effects model. Thirteen epidemiologic studies, published between 1983 and 2004, were included in the analysis, encompassing 5,663 patients with testicular cancer. Men weighing less than 2,500 grams at birth had a higher risk for developing testicular cancer later in life than those with normal birth weight (2,500-4,000 g) (OR = 1.18; 95% confidence interval (CI) 1.01-1.38). A similar trend was found for men with a birth weight above 4,000 g, (OR = 1.12; 95% CI 1.02-1.22). When seminoma and nonseminoma testicular cancer cases were considered separately, low birth weight was a risk factor specifically for seminomas (OR = 1.44; 95% CI 1.11-1.88). A U-shaped association was observed between birth weight and the risk for testicular cancer. The underlying biological mechanisms for this phenomenon remain to be elucidated.

Do testicular seminoma and nonseminoma share the same etiology? Evidence from an age-period-cohort analysis of incidence trends in eight European countries

The incidence of the two main clinical subentities of testicular germ cell cancer (seminoma and nonseminoma) is increasing throughout Europe. Most studies have revealed little variation in risk factors between the two subtypes. This study compared generation-specific trends in eight European countries, hypothesizing that similar temporal pattern by birth cohort implied that seminoma and nonseminoma had a largely comparable etiology. The results are presented using the age-period-cohort model and the nonidentifiability problem highlighted by partitioning the age, period, and cohort effects in terms of their linear and curvature component parts, assuming a priori that cohort effects predominated. Despite uniform overall increases by calendar period, declining rates of nonseminoma but not pure seminoma were observed in the majority of countries during the 1990s. The subtype trends were, however, largely analogous on a birth cohort scale. Notable observations were a decline in rates of both subtypes among recent birth cohorts in Switzerland and a short-term wartime effect in several countries, involving an attenuation of increasing risk of both subtypes in men born in 1940 to 1945. Departures from the steady increases in testicular cancer over time were likely to occur for nonseminomas some years ahead of seminoma on a period scale. The importance of birth cohort coincided with the view that given a short time interval of susceptibility to exposures earlier in life and a biologically constant time to diagnosis, all temporal changes in rate-limiting exposures should appear as generational effects. Trends in seminoma and nonseminoma conform to largely the same temporal patterns on this scale, implying that they share important etiologic factors.

Endocrine-disrupting chemicals and testicular cancer: a case-control study

Environmental factors appear to be important in the etiology of testicular cancer. In this study, the authors identified some risk factors for testicular cancer, paying particular attention to prenatal and early life exposure to endocrine-disrupting chemicals (EDCs). Using a questionnaire, the authors obtained information on male participants' environmental and occupational exposures during adolescence and adulthood. A multivariate logistic regression analysis of 103 cases and 215 controls showed an association between seminoma and nonseminoma and hobby activities that potentially involved the use of EDCs (eg, paints, glues, or solvents). Rural residence during adolescence was associated with all histological types of testicular cancer and with seminoma. No association was found with occupational exposures of the subjects. This study's findings also confirm previously identified risk factors, such as history of cryptorchidism and undescended testicle, high educational level, and low birth weight, and it gives some support to the hypothesis of a possible association between EDC exposures and testicular cancer.