Dietary risk factors for testicular carcinoma

Testicular cancer mortality in Latin America and the Caribbean: trend analysis from 1997 to 2019

BACKGROUND

In the last decades, an increasing incidence of testicular cancer has been observed in several countries worldwide. Although mortality rates have been variable in many countries, little information is available from Latin America and the Caribbean (LAC). Therefore, we examined mortality trends of testicular cancer in the last two decades.

METHODS

Age-standardized mortality rates (ASMR) of testicular cancer per 100,000 men-years were estimated using the World Health Organization mortality database from 1997 to 2019. We examined the mortality trends and computed annual percent change (APC) for all ages and the following age groups, 15-29, 30-44, 15-44, and ≥ 45 years.

RESULTS

Ten countries had mortality rates greater than 0.43 per 100,000 men, with the highest rates for Chile, Mexico, and Argentina. Significant increases in mortality rates were observed in Argentina, Brazil Colombia, and Mexico in all ages, and < 45 years, while Colombia, Ecuador, Mexico, and Peru reported significant downward trends in males aged ≥ 45 years. Only Chile showed significant decreases for all ages and age groups studied.

CONCLUSION

Mortality by testicular cancer increased among LAC countries in males of all ages and across age groups. A reduction in mortality rates was observed only in Chilean males of all ages and in men ≥ 45 years in several countries. Strengthening of early detection among symptomatic males may decrease the mortality by this neoplasm.

Risk Factors for Testicular Cancer: Environment, Genes and Infections-Is It All?

The incidence of testicular cancer is steadily increasing over the past several decades in different developed countries. If on one side better diagnosis and treatment have shone a light on this disease, on the other side, differently from other malignant diseases, few risk factors have been identified. The reasons for the increase in testicular cancer are however unknown while risk factors are still poorly understood. Several studies have suggested that exposure to various factors in adolescence as well as in adulthood could be linked to the development of testicular cancer. Nevertheless, the role of environment, infections, and occupational exposure are undoubtedly associated with an increase or a decrease in this risk. The aim of this narrative review is to summarize the most recent evidence regarding the risk factors associated with testicular cancer, starting from the most commonly evaluated (cryptorchidism, family history, infections) to the newer identified and hypothesized risk factors.

Trend analysis and regional tumor incidence in Germany for testicular cancer between 2003 and 2014

BACKGROUND

Testicular germ cell tumor (TGCT) is one the most common solid tumors in men between the age of 15 and 35 with an overall incidence rate of 1-1.5 %. Epidemiologic studies have demonstrated different incidence patterns in western civilized countries with overall rising incidence trends.

OBJECTIVE

To analyze differences in regional tumor incidence rates for TGCT and perform a trend analysis for TGCT between 2003 and 2014 in Germany.

MATERIAL AND METHODS

TGCT cases in Germany which were diagnosed between 2003 and 2014 were provided by the Robert-Koch-Institute, Berlin. For statistical analysis, cluster and spatial scan tests according to Kulldorff were used for cases with seminoma and non-seminoma. Results are presented in administrative districts and graphically illustrated. We performed a trend-analysis in order to evaluate age-adjusted incidence trends in Germany. Tests were two-sided with a level of significance of α=0.05.

RESULTS

In total we included 35,066 patients. Overall, 22,634 cases had newly diagnosed seminoma and 12,432 were diagnosed as non-seminoma. Maximum incidence of seminoma and non-seminoma was observed for age-group 38-40 years and 26-28 years, respectively. No second peak for the incidences of seminoma and non-seminoma with respect to age were observed. Cluster analysis revealed areas with high and low incidence rates as well as slightly different spatial distribution in Germany between seminoma and nonseminoma. Furthermore, there was no significant increase in age-adjusted incidence rates over the reviewed time period in both cohorts.

DISCUSSION

In this study differences in reginal tumor incidence rates for seminoma and non-seminoma are reported with both tumor entities revealing distinct clusters. Furthermore, tumor incidence trends for seminoma and nonseminoma between 2003 and 2014 were stable which might indicate the beginning of a plateau phase for TGCT incidence rates in Germany.

CONCLUSION

In this analysis we were able to identify regions with significantly higher tumor incidence rates for both seminoma and non-seminoma which were specific for these two subtypes. Furthermore, trend analysis revealed a steady incidence rate for testicular cancer in Germany.

Incident testicular cancer in relation to using marijuana and smoking tobacco: A systematic review and meta-analysis of epidemiologic studies

BACKGROUND

Recent epidemiologic studies identified credible associations between marijuana smoking and risk of nonseminomatous testicular germ cell tumors (TGCTs), but did not distinguish exposure to cannabinoid compounds from exposure to other constituents of smoke.

METHODS

We implemented a systematic review of scholarly literature followed by random effects meta-analysis to quantitatively synthesize published data relating incident TGCT to each of 2 exposure histories: ever using marijuana, and ever smoking tobacco.

RESULTS

We identified four epidemiologic studies of marijuana use and 12 of tobacco smoking. Summary data concur with earlier reports of a specific association of marijuana use with nonseminoma, summary odds ratio [sOR] = 1.71 (95% confidence interval [CI] 1.12-2.60), and identify a positive association, sOR = 1.18 (95% CI 1.05-1.33), between tobacco smoking and all TGCT.

CONCLUSIONS

Available data accord with positive associations between incident TGCT and each exposure, implicating both cannabinoid compounds and other constituents of smoke. Etiologic interpretation awaits epidemiologic studies that assess associations between tobacco smoking and nonseminomatous TGCT, investigating not only these exposures but also both co-use of tobacco and marijuana and smoke-free sources of cannabinoids, while adequately evaluating potential confounding among all of these exposures.

MECHANISMS IN ENDOCRINOLOGY: Estrogens in consumer milk: is there a risk to human reproductive health?

Possible effects of xenoestrogens on human health, in particular on male reproductive health, have attracted considerable attention in recent years. Cow's milk was suggested in numerous publications as one of possible sources of xenoestrogens that could affect human health. Although milk has undoubtedly many beneficial health effects and could even have a role in reducing incidence of some cancers, concerns were raised about presumably high levels of estrogens in cow's milk. In intensive farming, concentrations of estrogens in milk are higher due to long milking periods that today extend long into the pregnancy, when concentrations of estrogens in the cow's body rise. Numerous studies examined potential effects of milk on reproductive health and endocrine-related cancers in both experimental studies with laboratory animals, and in human epidemiological studies. In the present review article, we compiled a review of recently published literature about the content of estrogens in cow's milk and potential health effects, in particular on reproductive system, in humans. Although results of published studies are not unequivocal, it seems that there is stronger evidence suggesting that amounts of estrogens in cow's milk are too low to cause health effects in humans.

Dairy Consumption and Risk of Testicular Cancer: A Systematic Review

Dairy consumption has been studied extensively in terms of its relationship with testicular cancer (TC), yet this relationship remains unclear. In this systematic review, we aimed to answer whether TC development is associated with (a) high amounts of dairy product consumption, (b) the type of dairy product consumed, (c) increasing levels of dairy product consumption, and (d) dairy consumption during certain periods during the lifecourse. Following a systematic review of the literature, eight studies (all case-control studies) were included in our review. The included studies varied in terms of the dairy product(s) investigated (milk, cheese, cream, butter, and yoghurt) as well as the type of exposure to dairy consumption (e.g., high vs. low exposure, dose-response, and timing during lifecourse). We found that there was no strong evidence that high levels of dairy consumption are associated with risk of TC, conflicting evidence of a dose-response relationship, inconsistent evidence on whether certain types of dairy are more strongly associated with TC than others, and conflicting evidence that exposure during certain life-course periods affects TC risk more than other periods. There is no consistent evidence to support the premise that dairy product consumption is associated with the risk of TC development.

Time trends and occupational variation in the incidence of testicular cancer in the Nordic countries

OBJECTIVE

To describe the trends and occupational variation in the incidence of testicular cancer in the Nordic countries utilising national cancer registries, NORDCAN (NORDCAN project/database presents the incidence, mortality, prevalence and survival from >50 cancers in the Nordic countries) and NOCCA (Nordic Occupational Cancer) databases.

PATIENTS AND METHODS

We obtained the incidence data of testicular cancer for 5-year periods from 1960-1964 to 2000-2014 and for 5-year age-groups from the NORDCAN database. Morphological data on incident cases of seminoma and non-seminoma were obtained from national cancer registries. Age-standardised incidence rates (ASR) were calculated per 100 000 person-years (World Standard). Regression analysis was used to evaluate the annual change in the incidence of testicular cancer in each of the Nordic countries. The risk of testicular cancer in different professions was described based on NOCCA information and expressed as standardised incidence ratios (SIRs).

RESULTS

During 2010-2014 the ASR for testicular cancer varied from 11.3 in Norway to 5.8 in Finland. Until 1998, the incidence was highest in Denmark. There has not been an increase in Denmark and Iceland since the 1990s, whilst the incidence is still strongly increasing in Norway, Sweden, and Finland. There were no remarkable changes in the ratio of seminoma and non-seminoma incidences during the past 50 years. There was no increase in the incidences in children and those of pension age. The highest significant excess risks of testicular seminoma were found in physicians (SIR 1.48, 95% confidence interval [CI] 1.07-1.99), artistic workers (SIR 1.47, 95% CI 1.06-1.99) and religious workers etc. (SIR 1.33, 95% CI 1.14-1.56). The lowest SIRs of testicular seminoma were seen amongst cooks and stewards (SIR 0.56, 95% CI 0.29-0.98), and forestry workers (SIR 0.64, 95% CI 0.47-0.86). The occupational category of administrators was the only one with a significantly elevated SIR for testicular non-seminoma (SIR 1.21, 95% CI 1.04-1.42). The only SIRs significantly <1.0 were seen amongst engine operators (SIR 0.60, 95% CI 0.41-0.84) and public safety workers (SIR 0.67, 95% CI 0.43-0.99).

CONCLUSIONS

There have always been differences in the incidence of testicular cancer between the Nordic countries. There is also some divergence in the incidences in different age groups and in the trends of the incidence. The effect of occupation-related factors on incidence of testicular cancer is only moderate. Our study describes the differences, but provides no explanation for this variation.

Environmental Factors Affecting Growth and Occurrence of Testicular Cancer in Childhood: An Overview of the Current Epidemiological Evidence

Testicular cancer (TC) is the most frequently occurring malignancy among adolescents and young men aged 15–34 years. Although incidence of TC has been growing over the past 40 years in several western countries, the explanations for this increase still remain uncertain. It has been postulated that early life exposure to numerous occupational and environmental estrogenic chemicals, such as endocrine-disrupting chemicals (EDCs), may play a contributing role in the etiology of TC, but the subject is still open to additional investigation. Recently, it has also been suggested that prenatal and postnatal environmental exposures associated with child growth and development might also be involved in TC progression. This review of current epidemiological studies (2000–2015) aims to identify environmental factors associated with TC, with a particular focus on infancy and childhood factors that could constitute a risk for disease development. It may also contribute towards recognizing gaps in knowledge and recent research requirements for TC, and to point out possible interactions between child growth and development in relation to prenatal and postnatal environmental exposures.

Consumption of alcoholic beverages in adolescence and adulthood and risk of testicular germ cell tumor

The etiology of testicular germ cell tumor (TGCT) remains obscure and accumulating evidence suggests that postnatal environmental or lifestyle factors may play a role. To investigate whether consumption of alcoholic beverages during adolescence or adulthood is associated with TGCT risk, we analyzed data from a USA population-based case-control study of 540 18-44 year-old TGCT cases and 1,280 age-matched controls. Participants were queried separately about consumption of beer, wine and liquor during grades 7-8, grades 9-12 and the 5 years before reference date (date of diagnosis for cases and corresponding date for controls). We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association of TGCT risk with alcoholic beverage consumption during the different periods, both total and by specific beverage types and separately for seminomas and nonseminomas. Compared with nondrinkers in the 5 years before reference date, the OR (95% CI) for 1-6, 7-13 and ≥14 drinks per week were 1.20 (0.85, 1.69), 1.23 (0.81, 1.85) and 1.56 (1.03, 2.37), respectively (p-trend = 0.04). The corresponding results for alcohol consumption in grades 9-12 were 1.39 (1.06, 1.82), 1.07 (0.72, 1.60), 1.53 (1.01, 2.31) (p-trend = 0.05). Alcohol consumption in grades 7-8 was uncommon and no statistically significant associations with TGCT were observed. Associations with alcohol consumption in the 5 years before reference date appeared stronger for nonseminomas than for seminomas, but the differences were not statistically significant (p≥0.10). Associations were similar across different alcoholic beverage types. Consumption of alcoholic beverages may be associated with an increased TGCT risk.

Germ Cell Testicular Cancer Incidence, Latitude and Sunlight Associations in the United States and Australia

International patterns suggest germ cell testicular cancer (GCTC) incidence may be lower in lower latitudes. To investigate this possibility, we examined GCTC incidence by latitude (population centroid in 2000) for men ≥15 years within two reasonably homogeneous countries, the United States and Australia. In the United States, we examined age-adjusted incidence/latitude trends using data from states (2001-2010) and local-area registries (1980-2011). In Australia, we evaluated incidence/latitude trends in 61 Statistical Divisions (2000-2009). In U.S. White men (68 566 cases), state incidences increased by latitude, rising 5.74% (4.45-7.05%) per 5°North latitude increment. Similar trends were found for seminoma and nonseminoma subtypes (P < 0.001). In U.S. Black men (2256 cases), the association was also seen (4.9%; 0.2-9.7%). In local U.S. data, similar increases in incidence with latitude were present in each of the last three decades. In Australia (6042 cases), the incidence increased by 4.43% (95% CI: 1.54-7.39%) per 5°South, and trends for subtypes were similar. Thus, we found that incidence of GCTC in both White and Black men increased significantly with distance from the equator, approximately 1% per degree within the range of latitudes studied.

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.

Adaptation to Lactose in Lactase Non Persistent People: Effects on Intolerance and the Relationship between Dairy Food Consumption and Evalution of Diseases

Dairy foods contain complex nutrients which interact with the host. Yet, evolution of lactase persistence has divided the human species into those that can or cannot digest lactose in adulthood. Such a ubiquitous trait has differential effects on humanity. The literature is reviewed to explore how the divide affects lactose handling by lactase non persistent persons. There are two basic differences in digesters. Firstly, maldigesters consume less dairy foods, and secondly, excess lactose is digested by colonic microflora. Lactose intolerance in maldigesters may occur with random lactose ingestion. However, lactose intolerance without maldigestion tends to detract from gaining a clear understanding of the mechanisms of symptoms formation and leads to confusion with regards to dairy food consumption. The main consequence of intolerance is withholding dairy foods. However, regular dairy food consumption by lactase non persistent people could lead to colonic adaptation by the microbiome. This process may mimic a prebiotic effect and allows lactase non persistent people to consume more dairy foods enhancing a favorable microbiome. This process then could lead to alterations in outcome of diseases in response to dairy foods in lactose maldigesters. The evidence that lactose is a selective human prebiotic is reviewed and current links between dairy foods and some diseases are discussed within this context. Colonic adaptation has not been adequately studied, especially with modern microbiological techniques.

Exposure to polychlorinated biphenyls and hexachlorobenzene, semen quality and testicular cancer risk

PURPOSE

We carried out a case-control study to investigate the possible role of occupational and environmental exposure to endocrine disruptors in the onset of testicular cancer (TC).

METHODS

We evaluated 125 TC patients and 103 controls. Seminal fluid examination and organochlorine analysis were performed in all subjects. Cases and controls were also interviewed using a structured questionnaire to collect demographic information, residence, andrological medical history and dietary information.

RESULTS

We found that a higher level of reproductive tract birth defects was associated with a higher risk of TC. With regard to diet, cases reported a higher consumption of milk and dairy products than controls. Overall, there was a statistically significant increase in TC risk in cases with detectable values of total polychlorinated organic compounds against controls (14.4 vs. 1.0 %; p < 0.001). TC patients with detectable levels of organochlorines had lower mean semen parameters than those with undetectable levels, although this difference was not statistically significant.

CONCLUSION

The International Agency for Research on Cancer recently included dioxin-like polychlorinated biphenyls (PCBs) in Group 1 of known human carcinogens. Our study confirmed and identified various risk factors for testicular cancer: cryptorchidism, consumption of milk and dairy products, parents' occupation and serum concentration of hexachlorobenzene and PCBs and, for the first time, we showed the correlation between semen quality and the serum concentration of these pollutants.

Ten-year experience with testicular cancer at a tertiary care hospital in a resource-limited setting: a single centre experience in Tanzania

BACKGROUND

Testicular cancers constitute major therapeutic challenges in resource-limited countries and still carry poor outcomes. There is a paucity of published data regarding testicular cancer in Tanzania, and Bugando Medical Centre in particular. This study describes the clinicopathological pattern, treatment outcome and challenges in the management of testicular cancer in our local setting.

METHODS

This was a retrospective study including all patients who had had histopathologically confirmed testicular cancer at Bugando Medical Centre between February 2004 and January 2014.

RESULTS

A total of 56 testicular cancer patients were enrolled in the study, representing 0.9% of all malignancies. The median age of patients at presentation was 28 years, with a peak incidence in the 21-to-30-year age group. A family history of testicular cancer was reported in four (5.4%) patients. A history of cryptorchidism was reported in six (10.7%) patients. Most patients (57.1%) presented late with an advanced stage of cancer. Testicular swelling was the main complaint in 48 (85.7%) patients. The right testis was involved in 67.9% of cases. Lymph node and distant metastases were documented in 10 (17.9%) and 12 (21.4%) patients, respectively. Histologically, 80.4% of patients had germ cell cancers, with seminoma accounting for 62.2% of cases. The most common surgical procedure was inguinal orchidectomy (77.4%). Adjuvant chemotherapy and radiotherapy were used in six (11.1%) and four (7.4%) patients, respectively. Eight (14.3%) patients died. The main predictors of mortality (P<0.001) were patient's age (>65 years), late presentation (>6 months), stage of disease, and presence of metastasis at time of diagnosis. The mean follow-up period was 22 months. At the end of five years, only 18 (37.5%) patients were available for follow-up and the overall 5-year survival rate was 22.2%. The main predictors of 5-year survival rate (P<0.001) were patients' age, stage of disease, and presence of lymph node and distant metastases.

CONCLUSIONS

Testicular cancers, though rare in our setting, still carries a poor prognosis. Late presentation, poverty, paucity of resources and the high cost of newer imaging and treatment modalities are major challenges to management. Better health funding and education regarding testicular self-examination is essential.

Increasing incidence of testicular cancer in the United States and Europe between 1992 and 2009

PURPOSE

Increasing in incidence, testicular cancer is the most commonly diagnosed cancer in young men in the USA and in Europe. We sought to determine contemporary trends in testicular cancer incidence in the USA and Europe.

METHODS

Testicular cancer incidence data covering the USA and Europe were extracted from the SEER-13 (SEER*Stat 8.0.1) and the EUREG databases, respectively. Trends were determined using JoinPoint 3.5.3.

RESULTS

Testicular germ cell tumor (TGCT) incidence among US males >15 years increased from 1992 (5.7/100,000) to 2009 (6.8/100,000) with a significant annual percentage change (APC: 1.1%, p < 0.001). Seminomas were 29% of all TGCTs in 15-26 year-olds, increasing to 78% in those 40+ years of age. TGCT rates were highest in White men (1992: 7.5/100,000; 2009: 8.6/100,000) followed by Hispanic men (1992: 4.0/100,000; 2009: 6.3/100,000) and lowest among Asian (1992: 2.0/100,000; 2009: 2.8/100,000) and Black men (1992: 0.7/100,000; 2009: 1.7/100,000). Significantly increasing incidence rates were observed in White men (APC: 1.2%, p < 0.001) and most prominently in Hispanic men, especially from 2002 to 2009 (APC: 5.6%, p < 0.01). Incidence of testicular cancer increased in 15 of 19 (79%) European countries analyzed (p < 0.05). Denmark (13.4/100,000 man-years), Switzerland (12.7/100,000 man-years), and Norway (12.7/100,000 man-years) exhibited the highest age-standardized rates, while Spain had the greatest APC (APC = 5.5, 95% CI 3.9-7.0%, p < 0.001).

CONCLUSIONS

Between 1992 and 2009, testicular cancer incidence in the USA and Europe continued to increase, most notably in US Hispanic, Northern European, Spanish, and younger and older populations.

Adolescent and adult risk factors for testicular cancer

The incidence of testicular cancer has been increasing over the past several decades in many developed countries. The reasons for the increases are unknown because the risk factors for the disease are poorly understood. Some research suggests that in utero exposures, or those in early childhood, are likely to be important in determining an individual's level of risk. However, other research suggests that exposure to various factors in adolescence and adulthood is also linked to the development of testicular cancer. Of these, two adult occupational exposures-fire fighting and aircraft maintenance--and one environmental exposure (to organochlorine pesticides) are likely to be associated with increased risk of developing testicular cancer. By contrast, seven of the identified factors--diet, types of physical activity, military service, police work as well as exposure to ionizing radiation, electricity and acrylamide--are unlikely to increase the risk of developing testicular cancer. Finally, seven further exposures--to heat, polyvinyl chloride, nonionizing radiation, heavy metals, agricultural work, pesticides and polychlorinated biphenyls as well as marijuana use--require further study to determine their association with testicular cancer.

Ethnic and socioeconomic trends in testicular cancer incidence in New Zealand

Ethnic differences in testicular cancer incidence within countries are often sizeable, with white populations consistently having the highest ethnic-specific rates. Many studies have found that high socioeconomic status is a risk factor for testicular cancer. The objectives of this article are to test whether trends in testicular cancer incidence have varied by ethnicity and socioeconomic position in New Zealand between 1981 and 2004. Five cohorts of the entire New Zealand population for 1981-1986, 1986-1991, 1991-1996, 1996-2001 and 2001-2004 were created, and probabilistically linked to cancer registry records, allowing direct determination of ethnic and household income trends in testicular cancer incidence. There were more than 2,000 cases of testicular cancer over the study period. We found increasing rates of testicular cancer for all ethnic and income groups since 1990s. Maori had higher rates, and Pacific and Asian lower rates than European/other men with rate ratios pooled over time of 1.51 (95% CI 1.31-1.74), 0.40 (95% CI 0.26-0.61) and 0.54 (95% CI 0.31-0.94), respectively. Overall, men with low incomes had higher risk of testicular cancer than those with high incomes (pooled rate ratio for lowest to highest income groups = 1.23; 95% CI 1.05-1.44). There was no strong evidence that disparities in testicular cancer incidence have varied by ethnicity or household income over time. Given the lack of understanding of the etiology of testicular cancer, the unusual patterns identified in the New Zealand context may provide some etiological clues for future novel research.

Epidemiology of testicular cancer

Testicular cancer is of interest and importance because its incidence has been increasing in most countries over the past four decades. Although it remains an uncommon malignancy overall accounting for 1-2% of all tumours in men, testicular cancer is the most common malignancy in young men. There is marked geographical variation in the incidence of testicular cancer, with the highest incidence among men in Nordic countries and lowest incidence among men in the Middle East and Asia. The association between some risk factors, including cryptorchidism, a previous history of testicular cancer and a family history of testicular cancer, and the incidence of testicular cancer has been widely reported. We reviewed published reports and present the evidence to support or refute the association between the well-established and the less well-established risk factors and the incidence of testicular cancer.

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.

Molecular and cell biology of testicular germ cell tumors

Although testicular germ cell tumors (TGCTs) are relatively uncommon, they are particularly important as they tend to affect children and young men, representing the most common tumor in male aged from 20 to 40years. TGCTs are a heterogeneous group of tumors, with specific peculiarities reflecting on epidemiologic distribution and clinic-pathological features. TGCTs show a high-cure rates in both seminomas and nonseminomas and represent the model of a curable neoplasia: sensitive serum tumor markers, accurate prognostic classification, contribute to a high effectiveness of cancer therapy. However, up to 30% of patients diagnosed with metastatic nonseminomas do not achieve a durable remission, and in metastatic teratomas cisplatin-based treatment resistance has been observed. These different prognostic and therapeutic features of TGCTs highlight the need for a better understanding of the molecular biology of TGCT, that could help to improve disease management and to tailor aggressiveness of treatment to the severity of the prognosis.

Is increased body mass index associated with the incidence of testicular germ cell cancer?

PURPOSE

Epidemiological and ecological evidences suggest a positive association of overweight and obesity with the risk of testicular germ cell cancer (GCC). Previous controlled trials reported conflicting results. The present study aimed to analyse the putative association of overweight with GCC risk in a large patient sample and to summarize previous data.

METHODS

A total of 8,498 GCC patients were enrolled in a nationwide multicentric case control study. Self-reported body dimensions were recorded for calculation of the body mass index (BMI; kg/m(2)). For comparison, 2,070 age-matched male probands of the latest German National Health Survey (NHS) were employed. Patients and controls were categorized according to age as follows: 18-29, 30-39, and 40-49 years, respectively, and according to BMI, as follows: <18.5; 18.5 to <25; 25 to <30; >30 kg/m(2), respectively. Frequencies of BMI-categories in the three age groups were tabulated and compared statistically. The literature was searched for previous controlled trials regarding BMI and GCC risk.

RESULTS

The median BMI of all GCC patients is 24.69 kg/m(2). Overall comparison of frequencies of BMI categories of cases and controls did not reveal any significant difference. However, in young men (18-29 years) BMI categories 25 to <30 kg/m(2) and >30 kg/m(2) were significantly more frequent in GCC patients than in controls (p < 0.00001). Nineteen previous studies were identified in the literature, one of which being clearly in accordance with the present hypothesis, one being antithetical while the remaining studies were inconclusive in various aspects.

CONCLUSION

The results of this population-based study lend support to two hypotheses regarding the pathogenesis of GCC: First, as high-calorie nutrition is the most important reason for increased BMI, it appears conceivable that nutritional factors are involved in the pathogenesis of GCC. Second, as nonseminoma is the most prevalent histological subtype among younger patients, the association of increased BMI with incidence of GCC in this particular subgroup may point to divergent pathogenetic pathways of nonseminoma and seminoma, respectively.

Tallness is associated with risk of testicular cancer: evidence for the nutrition hypothesis

The pathogenesis of testicular germ cell tumours (GCTs) is potentially influenced by high-energy nutrition during infancy. As adult height is a proxy for childhood nutrition, we investigated the role of nutrition in GCT pathogenesis by comparing stature of patients with healthy men. In a matched case–control study, 6415 patients with GCT were compared with healthy army conscripts (1:6 matching modus) with regard to height (cm) and body mass index (BMI; kg/m²). Statistical analysis involved tabulation of descriptive height measures and BMI. Conditional logistic regression models were used to quantify the association of GCT with height, with odds ratios (OR) adjusted for BMI. The literature was searched for studies on stature in GCT patients. Body size is significantly associated with risk of GCT, very tall men (>195 cm) having a GCT risk of OR=3.35 (95% confidence intervals (CI): 2.88–3.90; adjusted). Short stature is protective (OR=0.798; 95% CI: 0.68–0.93). Both histologic subgroups are associated with tallness. Of 16 previous reports, 7 were confirmative, 5 had null and 4 equivocal results. The association of stature with GCT risk accords with the nutrition hypothesis of GCT. This study expands the current view of GCT tumorigenesis by suggesting that high-calorie intake in childhood promotes GCT precursors originating in utero.

Genes, chromosomes and the development of testicular germ cell tumors of adolescents and adults

Testicular germ cell tumors (TGCTs) of adults and adolescents are thought to be derived from primordial germ cells or gonocytes. TGCTs develop postpuberty from precursor lesions known as intratubular germ cell neoplasia undifferentiated. The tumors can be divided into two groups based on their histology and clinical behavior; seminomas resemble primordial germ cells or gonocytes and nonseminomas resemble embryonic or extraembryonic tissues at various stages of differentiation. The most undifferentiated form of nonseminoma, embryonal carcinoma, resembles embryonic stem cells in terms of morphology and expression profiling, both mRNAs and microRNAs. Evidence supports both environmental factors and genetic predisposition underlying the development of TGCTs. Various models of development have been proposed and are discussed. In TGCTs, gain of material from the short arm of chromosome 12 is invariable: genes from this region include the proto-oncogene KRAS, which has activating mutations in approximately 10% of tumors or is frequently overexpressed. A number of different approaches to increase the understanding of the development and progression of TGCTs have highlighted the involvement of KIT, RAS/RAF/MAPK, STAT, and PI3K/AKT signaling. We review the role of these signaling pathways in this process and the potential influence of environmental factors in the development of TGCTs.

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.

Risk factors for ovarian cancer: an overview with emphasis on hormonal factors

Ovarian cancer is the fifth most frequently occurring cancer among women and leading cause of gynecological cancer deaths in North America. Although the etiology of ovarian cancer is not clear, certain factors are implicated in the etiology of this disease, such as ovulation, gonadotropic and steroid hormones, germ cell depletion, oncogenes and tumor suppressor genes, growth factors, cytokines, and environmental agents. Family history of breast or ovarian cancer is a prominent risk factor for ovarian cancer, with 5-10% of ovarian cancers due to heritable risk. Reproductive factors such as age at menopause and infertility contribute to greater risk of ovarian cancer, whereas pregnancy, tubal ligation, and hysterectomy reduce risk. Oral contraceptive (OC) use has clearly been shown to be protective against ovarian cancer. In contrast, large epidemiologic studies found hormone replacement therapy (HRT) to be a greater risk factor for ovarian cancer. The marked influence of hormones and reproductive factors on ovarian cancer suggests that endocrine disrupters may impact risk; however, there is a notable lack of research in this area. Lifestyle factors such as cigarette smoking, obesity, and diet may affect ovarian cancer risk. Exposure to certain environmental agents such as talc, pesticides, and herbicides may increase risk of ovarian cancer; however, these studies are limited. Further research is needed to strengthen the database of information from which an assessment of environmental and toxicological risk factors for ovarian cancer can be made.

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.

Testicular cancer and male infertility

PURPOSE OF REVIEW

Testicular cancer and infertility affect a similar age group of patients and have common biologic, epidemiologic, and environmental backgrounds. In this review, we provide current literature on links between infertility and testicular cancer, and new developments in the management of testicular cancer aimed at improving quality of life in men with testicular cancer.

RECENT FINDINGS

In-utero environmental exposure to endocrine disruptors modulates the genetically determined fate of primitive gonad and results in testicular dysgenesis syndrome, which may result in infertility and testicular cancer. Excellent response of testicular cancer to radiation and chemotherapy results in over 90% of survival and quality of life--fertility and sexual function--is of significant concern to patients and clinicians. The testicular-sparing management of testicular masses emerges as a sound alternative to radical orchiectomy and allows for preservation of spermatogenesis and hormonal function, and at the same time achieving similar survival rates. Secondary malignancies, pulmonary, and cardiovascular complications are recognized as late complications of treatment for testicular cancer.

SUMMARY

Better understanding of common mechanisms involved in infertility and testicular cancer, and scientifically driven evidence-based treatment options should improve quality of life in young men faced with this potentially life-threatening disease.

Adolescent Milk Fat and Galactose Consumption and Testicular Germ Cell Cancer

Recent case-control studies suggested that dairy product consumption is an important risk factor for testicular cancer. We examined the association between consumption of dairy products, especially milk, milk fat, and galactose, and testicular cancer in a population-based case-control study including 269 case and 797 controls (response proportions of 76% and 46%, respectively). Dietary history was assessed by food frequency questions for the index persons and through their mothers including diet 1 year before interview and diet at age 17 years. We used conditional logistic regression to calculate odds ratios as estimates of the relative risk (RR), 95% confidence intervals (95% CI), and to control for social status and height. The RR of testicular cancer was 1.37 (95% CI, 1.12-1.68) per additional 20 servings of milk per month (each 200 mL) in adolescence. This elevated overall risk was mainly due to an increased risk for seminoma (RR, 1.66; 95% CI, 1.30-2.12) per additional 20 milk servings per month. The RR for seminoma was 1.30 (95% CI, 1.15-1.48) for each additional 200 g milk fat per month and was 2.01 (95% CI, 1.41-2.86) for each additional 200 g galactose per month during adolescence. Our results suggest that milk fat and/or galactose may explain the association between milk and dairy product consumption and seminomatous testicular cancer.

Serum cholesterol and testicular cancer incidence in 45,000 men followed for 25 years

In a 25-year follow-up study of 44 864 men with measured serum cholesterol levels, the testicular cancer hazard ratios for the serum cholesterol categories 5.7–6.9 and ⩾7.0 mmol l⁻¹vs the reference category (<5.7 mmol l⁻¹) were 1.3 and 4.5, respectively; P-value for trend=0.005. This highly significant association suggests that high-serum cholesterol is a risk factor for testicular cancer.

Germ cell tumors

PURPOSE OF REVIEW

This review provides an overview of some of the recent pre-clinical and clinical developments in germ cell tumors.

RECENT FINDINGS

Recent epidemiological studies highlight the variations in the geographic and ethnic distribution of germ cell tumors and the changing incidence of seminoma versus nonseminoma in the population. Additional studies are continuing to identify risk factors for germ cell tumors. Expression profiling, both at the gene and protein levels, is beginning to identify, at the molecular level, some of the factors associated not only with germ cell pluripotency but also with the different histologic subtypes of germ cell tumors. Work in the area of identifying potentially new serum tumor markers in germ cell tumor, as well as the role of the traditional tumor markers in predicting outcome to therapy is ongoing. Data is emerging on the role of positron emission tomography in evaluating residual lesions in seminoma. Evolving data on chemotherapy, radiation, and surgery further complements and clarifies information on these treatment modalities, and their potential toxicities, in the management of germ cell tumors.

SUMMARY

Ongoing preclinical and epidemiological studies highlight the complexities underlying germ cell tumor pathogenesis. With enhanced understanding of some of these processes, treatments, particularly for advanced stages, will continue to evolve.

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.

Testicular Cancer Incidence in Eight Northern European Countries: Secular and Recent Trends

Objective: Striking geographic variation and marked increasing secular trends characterize the incidence of testicular cancer. However, it is not known whether these patterns have attenuated in recent years and whether they are similar for seminomas and nonseminomas, the two main histologic groups of testicular cancer.

Method: Cancer registry data, including 27,030 testicular cancer cases, were obtained from Denmark, Estonia, Finland, Latvia, Lithuania, Norway, Poland, and Sweden. Between 57 (Denmark) and 9 (Poland) years of registration were covered. Country-specific temporal trends were estimated, with focus on the last decade and seminomas and nonseminomas. Data from the Nordic countries were further analyzed using an age-period-cohort approach.

Results: Age-standardized incidence rates increased annually by 2.6% to 4.9% during the study period, with marginal differences between seminomas and nonseminomas. In the last decade, the increasing trend attenuated only in Denmark (annual change, −0.3%; 95% confidence interval, −1.5 to 0.9). In 1995, the highest and the lowest age-standardized incidence rates (per 105) were 15.2 in Denmark and 2.1 in Lithuania. Incidence rates (i.e., for all cancers and for seminomas and nonseminomas, separately) depended chiefly on birth cohort rather than on calendar period of diagnosis (although both birth cohort and period determined the Danish incidence rates).

Conclusions: Testicular cancer incidence is still increasing, with the exception of Denmark, and a large geographic difference exists. The increasing trend is mainly a birth cohort phenomenon also in recent cohorts. Temporal trends for seminomas and nonseminomas are similar, which suggests that they share important causal factors.

Lignin-Stimulated Reduction of Oxidative DNA Lesions in Testicular Cells and Lymphocytes of Sprague-Dawley Rats In Vitro and Ex Vivo

Lignin biopolymers constitute 30% of plant biomass and belong to the most abundant organic polymers on earth. We showed previously that this important component of dietary fiber exhibited a protective effect against the overall DNA damage induced by H2O2 or N-methyl-N'-nitro-N-nitrosoguanidine in hamster lung cells and human foreskin cells cultured in vitro. The objective of the present work was to examine DNA-protective effects of lignin in rat testicular cells and rat peripheral blood lymphocytes using in vitro and ex vivo experiments. H2O2 and visible light-excited methylene blue (MB) were used as DNA-damaging agents. Testicular cells were chosen because the germinal epithelium of testes is one of the most proliferately active tissues potentially susceptible to DNA-damaging effects. As a second target peripheral blood lymphocytes were chosen because dietary lignin or its metabolites circulate in the animal organism probably through the blood system. For the in vitro experiments, isolated cells were preincubated with lignin for 2 h before treatment with one of the oxidative agents. In ex vivo experiments, the cells were exposed to H2O2 or visible light-excited MB after isolation from rats fed either a common diet or a lignin-supplemented diet. The water-soluble, sulfur-free lignin used in experiments was obtained by fractionation of hardwood hydrolysate. The level of direct single-strand DNA breaks in H2O2-treated cells was measured by the classical comet assay, and the level of oxidative DNA lesions in visible light-treated cells was measured by a modified comet assay. We found that lignin reduced DNA lesions induced by H2O2 or visible light-excited MB both in vitro and ex vivo. The major conclusion of our study is that lignin polymer obtained by fractionation of hardwood hydrolysate manifested a specific type of antimutagenic effect.

Clinical epidemiology of testicular germ cell tumors

Clinical epidemiology is sometimes called the basic science of clinical medicine. In terms of the pathogenesis of testicular germ cell tumors (GCTs), clinical epidemiology analyzes suspected risk factors. The present review highlights the risk factors established so far and briefly summarizes those factors currently under investigation. In analogy to the methods of evidence based medicine, this review attributes levels of evidence to each of the putative risk factors. Level I represents highest quality of evidence while level V denotes the lowest level. So far, undescended testis (UDT), contralateral testicular GCT and familial testis cancer are established risk factors attaining high levels of evidence (levels I-III a). In a meta-analysis of 21 studies exploring the association of UDT with GCT risk, an over-all relative risk (RR) of 4.8 (95% confidence interval 4.0-5.7) was found. Contralateral testicular GCT involves a roughly 25-fold increased RR of GCT, while familial testis cancer constitutes a RR of 3-10. Infertility, testicular atrophy, and twin-ship represent risk factors with lesser levels of evidence (level III a). There is also some evidence for HIV infection being a predisposing factor for GCT (level IV a). Scrotal trauma is probably not associated with GCT risk. The estrogen excess theory implies high estrogen levels during the first trimester of pregnancy. As a consequence, primordial germ cells lose track of the normal developmental line and transform into premalignant cells that later become testicular intraepithelial neoplasia (TIN), the precursor of full-blown testicular GCT. Surrogate parameters for high gestational estrogen levels are investigated in case control studies. Such factors are maternal age >30 years, first-born, low birth weight, maternal breast cancer, high sex-ratio of siblings. So far, the sum of evidence is promising but still conflicting (especially for level III b). Another novel theory is the childhood nutrition hypothesis. This concept postulates a modulating or "catalyzing" effect by high dietary intake during childhood on the pathogenesis of testicular GCT. A surrogate parameter of early childhood nutrition is adult height. So far, 12 controlled studies have looked to the possible association of attained height and GCT risk of which six demonstrated a significant association. Thus, the sum of evidence corresponds to level III b. This concept is appealing because it would explain several hitherto unexplained epidemiological features of GCT.