Oncologic outcomes of patients with incidental prostate cancer who underwent RARC: a comparison between nerve sparing and non-nerve sparing approach

BACKGROUND

Incidental Prostate cancer (iPCa) is a relatively common finding during histopathological evaluation of radical cystectomy (RC) specimens. To reduce the high impact of RC on erectile function, several sexual-preserving techniques have been proposed. The aim of this study was to evaluate and compare the oncologic outcomes of patients with iPCa who underwent nerve spring and no-nerve sparing robot-assisted radical cystectomy (RARC).

METHODS

The clinicopathologic data of male patients who underwent RARC at our institution between 2006 and 2016 were retrospectively analysed. Patients with iPCa at definitive pathological examinations were stratified in two groups, according to the preservation of the neurovascular bundles (nerve sparing vs no nerve sparing). Significant PCa was defined as any Gleason score ≥ 3 + 4. Biochemical recurrence (BR) was defined as a sustained PSA level > 0.2 ng/mL on two or more consecutive appraisals. BR rate was assessed only in patients with incidental prostate cancer and at least 2 years of follow-up. Differences in categorical and continuous variables were analysed using the chi-squared test and the Mann-Withney U test, respectively. Biochemical recurrence curves were generated using the Kaplan-Meier method and compared with the Log-rank test.

RESULTS

Overall, 343 male patients underwent RARC for bladder cancer within the study period. Nerve-sparing surgery was performed in 143 patients (41%), of these 110 had at least 2 years of follow up after surgery. Patients who underwent nerve-sparing surgery were significantly younger (p < 0.001). Clinically significant PCa was found in 24% of patients. No significant differences regarding preoperative PSA value (p = 0.3), PCa pathological stage (p = 0.5), Gleason score (p = 0.3) and positive surgical margin rates (p = 0.3) were found between the two groups. After a median follow-up of 51 months only one patient, in the no-nerve-sparing group had developed a biochemical recurrence (p = 0.4).

CONCLUSIONS

In our series most of the iPca detected in RC specimens can be considered as insignificant with a low rate of BR (0.9%). Nerve-sparing RARC is a safe procedure which did not affect oncological outcomes of patients with iPCa.

SPCG-15: a prospective randomized study comparing primary radical prostatectomy and primary radiotherapy plus androgen deprivation therapy for locally advanced prostate cancer

OBJECTIVE

To describe study design and procedures for a prospective randomized trial investigating whether radical prostatectomy (RP) ± radiation improves cause-specific survival in comparison with primary radiation treatment (RT) and androgen deprivation treatment (ADT) in patients with locally advanced prostate cancer (LAPC).

MATERIALS AND METHODS

SPCG-15 is a prospective, multi-centre, open randomized phase III trial. Patients are randomized to either standard (RT + ADT) or experimental (RP with extended pelvic lymph-node dissection and with addition of adjuvant or salvage RT and/or ADT if deemed necessary) treatment. Each centre follows guidelines regarding the timing and dosing of postoperative RT and adjuvant treatment such as ADT The primary endpoint is cause-specific survival. Secondary endpoints include metastasis-free and overall survival, quality-of-life, functional outcomes and health-services requirements. Each subject will be followed up for a minimum of 10 years.

RESULTS

Twenty-three centres in Denmark, Finland, Norway and Sweden, well established in performing RP and RT for prostate cancer participated. Each country's sites were coordinated by national coordinating investigators and sub-investigators for urology and oncology. Almost 400 men have been randomized of the stipulated 1200, with an increasing rate of accrual.

CONCLUSIONS

The SPCG-15 trial aims to compare the two curatively intended techniques supplying new knowledge to support future decisions in treatment strategies for patients with LAPC The Scandinavian healthcare context is well suited for performing multi-centre long-term prospective randomized clinical trials. Similar care protocols and a history of entirely tax-funded healthcare facilitate joint trials.

External validation of models predicting the individual risk of metachronous peritoneal carcinomatosis from colon and rectal cancer

AIM

To externally validate previously published predictive models of the risk of developing metachronous peritoneal carcinomatosis (PC) after resection of nonmetastatic colon or rectal cancer and to update the predictive model for colon cancer by adding new prognostic predictors.

METHOD

Data from all patients with Stage I-III colorectal cancer identified from a population-based database in Stockholm between 2008 and 2010 were used. We assessed the concordance between the predicted and observed probabilities of PC and utilized proportional-hazard regression to update the predictive model for colon cancer.

RESULTS

When applied to the new validation dataset (n = 2011), the colon and rectal cancer risk-score models predicted metachronous PC with a concordance index of 79% and 67%, respectively. After adding the subclasses of pT3 and pT4 stage and mucinous tumour to the colon cancer model, the concordance index increased to 82%.

CONCLUSION

In validation of external and recent cohorts, the predictive accuracy was strong in colon cancer and moderate in rectal cancer patients. The model can be used to identify high-risk patients for planned second-look laparoscopy/laparotomy for possible subsequent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

Selective intraoperative cholangiography and risk of bile duct injury during cholecystectomy

Background

Whether intraoperative cholangiography can prevent iatrogenic bile duct injury during cholecystectomy remains controversial.

Methods

Data from the national Swedish Registry for Gallstone Surgery, GallRiks (May 2005 to December 2010), were analysed for evidence of iatrogenic bile duct injury during cholecystectomy. Patient- and procedure-related risk factors for bile duct injury with a focus on the rate of intended intraoperative cholangiography were analysed using multivariable logistic regression.

Results

A total of 51 041 cholecystectomies and 747 bile duct injuries (1·5 per cent) were identified; 9008 patients (17·6 per cent) were diagnosed with acute cholecystitis. No preventive effect of intraoperative cholangiography was seen in uncomplicated gallstone disease (odds ratio (OR) 0·97, 95 per cent c.i. 0·74 to 1·25). Operating in the presence (OR 1·23, 1·03 to 1·47) or a history (OR 1·34, 1·10 to 1·64) of acute cholecystitis, and open surgery (OR 1·56, 1·26 to 1·94), were identified as significant risk factors for bile duct injury. The intention to perform intraoperative cholangiography was associated with a reduced risk of bile duct injury in patients with concurrent (OR 0·44, 0·30 to 0·63) or a history of (OR 0·59, 0·35 to 1·00) acute cholecystitis.

Conclusion

Any proposed protective effect of intraoperative cholangiography was restricted to patients with (or a history of) acute cholecystitis.

Individualized prediction of risk of metachronous peritoneal carcinomatosis from colorectal cancer

AIM

The purpose of the study was to develop a tool for predicting the individual risk of metachronous peritoneal carcinomatosis after surgery for non-metastatic colorectal cancer.

METHOD

Independent predictors for metachronous colorectal carcinomatosis have previously been identified using a population-based database. Predictive models for colon and rectal cancer were developed from these data. The predictive models were based on multivariable Cox proportional hazard regression and were internally validated with bootstrapping. Performance was assessed by the concordance index and calibration plots.

RESULTS

In all, 8044 patients who underwent abdominal resection of colorectal cancer Stage I-III were included. The colon and rectal cancer risk score models predicted metachronous peritoneal carcinomatosis with a concordance index of 80% and 78%, respectively. Factors in the models included age, pathological pT stage, pN stage, number of examined lymph nodes (0-11, 12+), type of surgery (emergency/elective), completeness of cancer resection (R0/R1/R2), adjuvant chemotherapy (yes/no), preoperative radiotherapy and tumour location.

CONCLUSION

The proposed predictive models showed high internal validity and enabled individualized prediction of peritoneal recurrence of colorectal cancer. The models may help in the planning of treatment and follow-up of patients. However, external validation is warranted to assess generalizability of the predicted absolute risks.

Long-term valacyclovir suppressive treatment after herpes simplex virus type 2 meningitis: a double-blind, randomized controlled trial

BACKGROUND

Herpes simplex virus type 2 (HSV-2) is a common cause of acute and recurrent aseptic meningitis. Our aim was to determine the impact of antiviral suppression on recurrence of meningitis and to delineate the full spectrum of neurological complications.

METHODS

One hundred and one patients with acute primary or recurrent HSV-2 meningitis were assigned to placebo (n = 51) or 0.5 g of valacyclovir twice daily (n = 50) for 1 year after initial treatment with 1 g of valacyclovir 3 times daily for 1 week in a prospective, placebo-controlled, multicenter trial. The primary outcome was time until recurrence of meningitis. The patients were followed up for 2 years.

RESULTS

The first year, no significant difference was found between the valacyclovir and placebo groups. The second year, without study drugs, the risk of recurrence of verified and probable HSV-2 meningitis was significantly higher among patients exposed to valacyclovir (hazard ratio, 3.29 [95% confidence interval, 10.06-10.21]). One-third of the patients experienced 1-4 meningitis episodes during the study period. A considerable morbidity rate, comprising symptoms from the central, peripheral, and autonomous nervous system, was found in both groups.

CONCLUSIONS

Suppressive treatment with 0.5 g of valacyclovir twice daily was not shown to prohibit recurrent meningitis and cannot be recommended for this purpose after HSV meningitis in general. Protection against mucocutaneous lesions was observed, but the dosage was probably inappropriate for the prevention of HSV activation in the central nervous system. The higher frequency of meningitis, after cessation of active drug, could be interpreted as a rebound phenomenon.

Soluble urokinase plasminogen activator receptor as a prognostic marker in men participating in prostate cancer screening

BACKGROUND

The urokinase plasminogen activator (uPA) system is involved in tissue remodelling processes and is up-regulated in many types of malignancies. We investigated whether serum levels of different forms of soluble uPA receptor (suPAR) are associated with survival and in particular with prostate cancer and cardiovascular disease mortality.

METHODS

Using time-resolved fluorescence immunoassays, we measured intact suPAR [suPAR(I-III)] and intact plus cleaved suPAR [suPAR(I-III) + suPAR(II-III)] and thus calculated the amount of suPAR(II-III) in serum samples from 375 men participating in a prostate cancer screening trial. A total of 312 men were free of prostate cancer and 63 men had prostate cancer diagnosed at the time of screening. The cohort was followed for 15 years. We assessed survival using Kaplan-Meier estimation and Cox proportional hazards regression.

RESULTS

The mean age at blood sampling was 64 years. In total, 152 men died during follow-up. SuPAR(I-III) and suPAR(II-III) were significantly positively associated with mortality (P = 0.001 and P < 0.0001, respectively). In a Cox regression model adjusting for age and prostate cancer status, an increase in suPAR(I-III) and suPAR(II-III) by 1-unit (ln-scale) was associated with a hazard ratio (HR) of 2.26 [95% confidence interval (CI) 1.17-4.35] and 2.53 (95% CI 1.56-4.10), respectively. There was a trend towards an increased risk of death from prostate cancer in screening-detected prostate cancer patients with increased values of either suPAR form. However, this difference was not significant and the association disappeared after adjusting for age, tumour stage, tumour grade and prostate-specific antigen. Being in the highest quartile of any of the suPAR forms was associated with a highly significant increased risk of cardiovascular death, with HR adjusted for age of 3.27 (95% CI 1.38-7.73) for suPAR(I-III) quartile 4 versus quartile 1. Conclusions.  High concentrations of serum suPAR(I-III) and suPAR(II-III) were associated with poor overall survival. The association was particularly strong for death from cardiovascular disease. No similar association was found for prostate cancer after adjustment for other prognostic factors.

Rates of orchiopexies in Sweden: 1977-1991

Cryptorchidism is a known risk factor for testicular cancer and the secular increase in testicular cancer incidence might have been paralleled by a similar increase in cryptorchidism. Data on trends in prevalence of cryptorchidism are however conflicting and decreases have recently been reported. To analyse Swedish trends in rates of orchiopexy, we used the Swedish Hospital Discharge Register to identify all cases of orchiopexy carried out for cryptorchidism between 1977 and 1991, that is, before the era of outpatient orchiopexies in Sweden. Observed trends were analysed in 5-year age groups. The estimated average annual per cent changes (EAPCs) and the years in which the EAPC significantly changed were estimated using Joinpoint Regression. Finally, we estimated the cumulative incidence of orchiopexy by birth cohort. Among boys aged less than 10, the orchiopexy rate started to decrease in the early 1980s. EAPCs were -2.88 (95% confidence interval (CI): -5.48, -0.21) among boys aged 5-9 and -6.63 among those aged 0-4 (95% CI: -8.84, -4.37). Among subjects aged at least 10, the rate decreased over the whole study period. Although the use of orchiopexy rates to measure prevalence of cryptorchidism has limitations, our findings may suggest that cryptorchidism prevalence decreased in Sweden starting from the early 1980s.

Preterm birth, birth weight, and subsequent risk of female breast cancer

We have previously found an increased risk of breast cancer among women born preterm. To confirm or refute the results, an enlarged study was conducted. The results from this study do not confirm the initial findings and suggest that preterm birth can be ruled out as a risk factor for breast cancer.

No association between human parvovirus B19 and testicular germ cell cancer

The incidence of testicular germ cell cancer, which is the most common cancer among young male adults, is increasing. The aetiology remains unknown, although a virus has been proposed. A previous study has shown a high prevalence of human parvovirus B19 (B19) DNA in the testes of patients with testicular germ cell tumours (85%) and suggested that B19 may play a role in tumour development. To address this question of causality, seroreactivity to B19 was studied among cases (n=80) and controls (n=241) using serum samples drawn before the onset of disease, in addition to an elucidation of the frequency of virus DNA in a retrospectively collected 2-year testicular carcinoma series. No association was found between B19 seropositivity and the risk of testicular cancer (odds ratio=1.03; 95% confidence interval=0.60-1.77) nor was there any dose-response relation (P for trend=0.53). This study did, however, confirm the observation that B19 DNA can be detected in testicular carcinoma tissue, as 4 of 24 cases were found to be positive, while no B19 DNA could be detected in the control cases. It is speculated that this finding may be due to susceptibility of the carcinoma cells to B19 virus owing to high-level expression of the viral receptor glycosphingolipid (Gb4) and possible other putative cellular factors resulting in a localized persistence initiated after the development of cancer.

Perinatal determinants of germ-cell testicular cancer in relation to histological subtypes

We aimed to investigate the role of perinatal determinants on the risk for germ-cell testicular cancer, with respect to the aetiological heterogeneity between seminomas and non-seminomas. A case-control study of 628 case patients with testicular cancer (308 seminomas and 320 non-seminomas) and 2309 individually matched controls was nested within a cohort of boys born from 1920 to 1980 in two Swedish regions (Uppsala-Orebro Health Care Region and Stockholm). Cases were diagnosed from 1958 to 1998 and were identified through the Swedish National Cancer Registry. Perinatal information on cases and controls was collected through charts available at maternity wards. Gestational duration, categorised in three categories (<37, 37-41, >41 weeks), was negatively associated with the risk for testicular cancer (P value for linear trend=0.008). A protective effect of long gestational duration and an increased risk for high birth weight were found for seminomas. Non-seminomas were associated with short gestational duration, particularly among those with low birth order (odds ratio: 3.02, 95% confidence intervals: 1.53-5.97) and high maternal age (odds ratio: 2.33, 95% confidence intervals: 1.19-4.55). No significant differences were found in tests for heterogeneity between the two histological groups. Our data support the hypothesis that intrauterine environment affects the risk for germ-cell testicular cancer. Seminomas and non-seminomas seemed to have similar risk patterns, although they are not entirely congruent.

Early life exposure to oestrogen and testicular cancer risk: evidence against an aetiological hypothesis

British Journal of Cancer (2002) 86, 1363–1364. DOI: 10.1038/sj/bjc/6600246www.bjcancer.com

© 2002 Cancer Research UK

Sickness in pregnancy and sex of child

We report a female predominance among the offspring of mothers with hyperemesis gravidarum.

Epstein-Barr virus and cytomegalovirus in relation to testicular-cancer risk: a nested case-control study

An infectious etiology of testicular cancer has been suggested. We have evaluated seroreactivity against cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in relation to testicular-cancer risk in a case-control study, nested within a cohort of prospectively collected serum specimens from 293,692 individuals. For each of 81 cases of testicular cancer identified, 3 controls were randomly selected from the cohort. Serum IgG antibody titers against CMV and EBV were determined using enzyme-linked immunosorbent assays (ELISAs) and immunofluorescence methods. Odds ratios (OR) were obtained from conditional logistic-regression models. No association was found between CMV positivity and testicular cancer overall (OR = 1.08; 95% confidence interval 0.60-1.94); risk for testicular seminoma was increased among CMV seropositive [OR = 1.70 (0.80-3.59)], whereas seropositivity was associated with decreased risk for testicular non-seminoma [OR = 0.54 (0.19-1.56)] (p for heterogeneity, 0.09). For EBV, the risk for testicular cancer was increased among individuals seropositive for viral capsid antigen (VCA) [OR = 2.74 (0.62-12.12)]. The results lend some support to the hypothesis of an infectious etiology, and we propose that future studies should take into account age at infection.

Risk factor patterns for cryptorchidism and hypospadias

To evaluate the hypothesis of a common etiology for cryptorchidism and hypospadias, we conducted two case-control studies nested in a nationwide cohort in Sweden, using record linkage between the Inpatient and Birth Registries. Cases were 2,782 and 1,220 boys operated for cryptorchidism or hypospadias, respectively. Five matched controls per case were randomly selected. Pregnancy and perinatal data were prospectively recorded in the Birth Registry. Data were modeled through conditional logistic regression. Both cryptorchidism (odds ratio (OR) = 2.22) and hypospadias (OR = 2.75) were positively associated with other congenital malformations and inversely with maternal parity (OR = 0.77 and 0.52, respectively, for parity 4+ compared with primiparae). There is evidence that being born small-for-gestational-age and before the 33rd gestational week have a greater-than-additive effect with respect to both cryptorchidism (OR = 6.19 vs 1.72 expected) and hypospadias (OR = 4.39 vs 2.60 expected) compared with non-small-for-gestational-age boys born at term. Hypospadias was positively associated with severe preeclampsia (OR = 2.11). We conclude that the etiologies of the two conditions are partly shared.

Epstein-Barr virus and cytomegalovirus in relation to testicular-cancer risk: a nested case-control study

An infectious etiology of testicular cancer has been suggested. We have evaluated seroreactivity against cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in relation to testicular-cancer risk in a case-control study, nested within a cohort of prospectively collected serum specimens from 293,692 individuals. For each of 81 cases of testicular cancer identified, 3 controls were randomly selected from the cohort. Serum IgG antibody titers against CMV and EBV were determined using enzyme-linked immunosorbent assays (ELISAs) and immunofluorescence methods. Odds ratios (OR) were obtained from conditional logistic-regression models. No association was found between CMV positivity and testicular cancer overall (OR = 1.08; 95% confidence interval 0.60-1.94); risk for testicular seminoma was increased among CMV seropositive [OR = 1.70 (0.80-3.59)], whereas seropositivity was associated with decreased risk for testicular non-seminoma [OR = 0.54 (0.19-1.56)] (p for heterogeneity, 0.09). For EBV, the risk for testicular cancer was increased among individuals seropositive for viral capsid antigen (VCA) [OR = 2.74 (0.62-12.12)]. The results lend some support to the hypothesis of an infectious etiology, and we propose that future studies should take into account age at infection.

Human fertility does not decline: evidence from Sweden

OBJECTIVE

To assess changes in human fertility over time.

DESIGN

Time-trend analyses and age-period-cohort modeling.

SETTING

Sweden, 1983-1993.

PATIENT(S)

All primiparous women aged > or =20 years during the study period. There were 401,653 women who were identified through the nationwide Medical Birth Register.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Risk of subfertility, defined as > or =1 year of involuntary childlessness.

RESULT(S)

Subfertility problems decreased dramatically over successive maternal birth cohorts. Further, the risk of subfertility increased with age and decreased with increasing formal education.

CONCLUSION(S)

A decrease in male fertility cannot be ruled out on the basis of these results, but if present, it is minor and totally outweighed by other favorable developments. As the main explanation for our findings, we propose a decrease in the prevalence of secondary subfertility as a result of the eradication of gonorrhea.

Increasing incidence of testicular cancer--birth cohort effects

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

Testicular nonseminoma and seminoma in relation to perinatal characteristics

BACKGROUND

Testicular cancer incidence peaks during the third decade of life, and an increasing trend in the occurrence of this disease has been seen in many countries. Few risk factors have been established for testicular cancer, but evidence suggests that causal factors operate early in life, perhaps even in utero.

PURPOSE

We performed a case-control study to evaluate specific perinatal characteristics as risk factors for the two main histopathologic types of testicular cancer: seminomas and nonseminomas.

METHODS

Two hundred thirty-two case patients with invasive testicular cancer and 904 individually matched control subjects (all singleton births), nested in a cohort of men born at 10 hospitals in Sweden from 1920 through 1978, were included in the study. Perinatal information about the study subjects and their parents was obtained from birth records. For the mothers, information was recorded concerning age at menarche, marital status, parity, age at delivery, maternal weight at delivery and at first visit to a maternal-care center, education and/or profession, and any medical problems encountered during pregnancy or after delivery. For the fathers, information was obtained concerning age at delivery and education and/or profession. For the study subjects, information was recorded about the following: gestational age, birth length and weight, placental weight, method of delivery (normal, cesarean section, or with forceps or vacuum extractor), medical problems during hospital stay, presence of jaundice, method of feeding at discharge, and duration of hospital stay after birth. Individuals diagnosed with testicular cancer were identified through the Swedish National Cancer Registry and the Uppsala Regional Cancer Registry. The data were analyzed by use of conditional logistic regression modeling.

RESULTS

When testicular cancer was modeled as a single entity, significantly elevated risks were associated with neonatal jaundice (adjusted odds ratio [OR] = 2.30; 95% confidence interval [CI] = 1.07-4.94) and with either low (< 2500 g) or high (> or = 4000 g) birth weight (OR = 2.59; 95% CI = 1.05-6.38 and OR = 1.58; 95% CI = 1.10-2.29, respectively). When seminomas and nonseminomas were analyzed separately, high maternal socioeconomic status (OR = 2.54; 95% CI = 1.05-6.12), neonatal jaundice (OR = 3.96; 95% CI = 1.47-10.69), and low birth weight (OR = 7.62; 95% CI = 1.59-36.60) were associated with nonseminomas, whereas high placental weight (OR = 3.50; 95% CI = 0.97-12.62) suggested increased risk for seminomas.

CONCLUSIONS AND IMPLICATIONS

Perinatal exposures appear to influence the risk of testicular cancer, and seminomas and nonseminomas may have somewhat different risk profiles. Future epidemiologic studies should consider the possibility of etiologic heterogeneity in the development of seminomas and nonseminomas.

Increase in testicular cancer incidence in six European countries: a birth cohort phenomenon

BACKGROUND

For unknown reasons, the age-standardized incidence of testicular cancer has shown a rapid increase in virtually all countries (mostly Western) studied. For populations with a sufficiently long period of cancer registration, this development can be traced back to the first half of this century.

PURPOSE

By evaluating data from six countries with long periods of cancer registration (Denmark, Norway, Sweden, the former German Democratic Republic [East Germany], Finland, and Poland), we sought to determine whether the increase in testicular cancer risk follows a birth cohort pattern and, if so, to quantify and compare any birth cohort effects.

METHODS

A total of 30,908 incident cases of testicular cancer, diagnosed from 1945 through 1989 in men who were 20-84 years of age, were identified in population-based cancer registries in the six countries. In addition to performing simple trend analyses, we fitted several Poisson regression models (with the explanatory variables age, time period [calendar time], and birth cohort) to the data. Individual models were estimated by the maximum likelihood method.

RESULTS

The age-standardized incidence of testicular cancer was found to vary among the six populations and, on the basis of total registration data, increased annually at rates ranging from 2.3% (in Sweden) to 5.2% (in East Germany). A comparison of several regression models indicated that birth cohort was a stronger determinant of testicular cancer risk than was calendar time for all six populations. Within each population, little variation in testicular cancer risk was observed for men born between 1880 and 1920; thereafter, the risk began to increase. Among men born in Denmark, Norway, and Sweden between 1930 and 1945 (the period encompassing the Second World War), the increasing trend in risk was interrupted (i.e., a leveling in risk occurred). After 1945, an uninterrupted increase in risk was observed for all six populations. With men born around 1905 as the reference group, the relative risk of testicular cancer for those born around 1965 varied from 3.9 (95% confidence interval [CI] = 2.7-5.6) in Sweden to 11.4 (95% CI = 8.3-15.5) in East Germany.

CONCLUSIONS AND IMPLICATIONS

The increasing trend in testicular cancer risk observed for these six populations follows a birth cohort pattern. This distinct risk pattern provides a framework for the identification of specific etiologic factors.