Uptake of doublet therapy for de novo metastatic castration sensitive prostate cancer: a population-based drug utilisation study in Sweden.

BACKGROUND: Randomised controlled trials have demonstrated prolonged survival with new upfront treatments in addition to standard androgen deprivation therapy (ADT) in men with de novo metastatic castration-sensitive prostate cancer. We describe patient characteristics, time trends and regional differences in uptake of these new treatment strategies in clinical practice. MATERIAL AND METHODS: This descriptive study consisted of men registered in the National Prostate Cancer Register of Sweden from 1 January 2018 to 31 March 2022 with de novo metastatic castration-sensitive prostate cancer defined by the presence of metastases on imaging at the time of diagnosis. Life expectancy was calculated based on age, Charlson Comorbidity Index and a Drug Comorbidity Index. RESULTS: Within 6 months from diagnosis, 57% (1,677/2,959) of men with de novo metastatic castration-sensitive prostate cancer and more than 3 years of life expectancy had received docetaxel, abiraterone, enzalutamide, apalutamide and/or radiotherapy. Over time, there was a 2-fold increase in uptake of any added treatment, mainly driven by a 6-fold increase in use of abiraterone, enzalutamide or apalutamide, with little change in use of other treatments. CONCLUSIONS: Slightly more than half of men diagnosed with de novo metastatic castration-sensitive prostate cancer and a life expectancy of at least 3 years received additions to standard ADT as recommended by national guidelines in 2019-2022 in Sweden. There was a 2-fold increase in use of these treatments during the study period; however, efforts to further increase adherence to guidelines are warranted.

Time difference in retrieving clinical information in Patient-overview Prostate Cancer compared to electronic health records.

BACKGROUND: Patients with advanced prostate cancer (PCa) typically undergo numerous lines of treatment leading to large amounts of information in Electronic Health Records (EHRs). The Patient-overview Prostate Cancer (PPC) presents clinical information in a graphical overview. The aim of this study was to measure time spent on retrieving clinical information in PPC compared to EHRs, to assess if retrieved data was correct and to explore usability of PPC. MATERIAL AND METHODS: Oncologists, urologists and nurses in three hospitals in Sweden were timed when filling out questionnaires about patients using PPC and two different EHRs; Melior and COSMIC. Time and number of errors were analysed using linear mixed models (LMMs). Usability of PPC was measured with the System Usability Scale. RESULTS: The LMM showed a significantly shorter time to retrieve information in PPC compared to EHRs. The estimated time to complete one questionnaire was 8 minutes (95% CI = 6-10, p < 0.001) in PPC compared to 25 minutes in Melior and 21 minutes in COSMIC. Compared to PPC, the estimated time difference was 17 minutes longer in Melior (95% CI = 14-20, p < 0.001) and 13 minutes longer in COSMIC (95% CI = 10-17, p < 0.001). The LMM showed significantly fewer errors in PPC compared to Melior. No significant difference in the number of errors was found between PPC and COSMIC. The usability of PPC was rated as excellent by oncologists, urologists and nurses. CONCLUSION: A graphical overview of a patient's medical history, as in PPC, gives health staff rapid access to relevant information with a high degree of usability.

The Value of Real-World Data in Understanding Prostate Cancer Risk and Improving Clinical Care: Examples from Swedish Registries.

Real-world data (RWD), that is, data from sources other than controlled clinical trials, play an increasingly important role in medical research. The development of quality clinical registers, increasing access to administrative data sources, growing computing power and data linkage capacities have contributed to greater availability of RWD. Evidence derived from RWD increases our understanding of prostate cancer (PCa) aetiology, natural history and effective management. While randomised controlled trials offer the best level of evidence for establishing the efficacy of medical interventions and making causal inferences, studies using RWD offer complementary evidence about the effectiveness, long-term outcomes and safety of interventions in real-world settings. RWD provide the only means of addressing questions about risk factors and exposures that cannot be "controlled", or when assessing rare outcomes. This review provides examples of the value of RWD for generating evidence about PCa, focusing on studies using data from a quality clinical register, namely the National Prostate Cancer Register (NPCR) Sweden, with longitudinal data on advanced PCa in Patient-overview Prostate Cancer (PPC) and data linkages to other sources in Prostate Cancer data Base Sweden (PCBaSe).

Set-up and preliminary results from the Patient-overview Prostate Cancer. Longitudinal registration of treatment of advanced prostate cancer in the National Prostate Cancer Register of Sweden.

Introduction: Novel drugs have been shown to prolong life in men with metastatic prostate cancer (PCa) and castration resistant Pca (CRPC). The aim of Patient-overview Prostate cancer (PPC) is to register and report these treatments and their effect.Material and methods: In PPC, a new part of the National Prostate Cancer Register of Sweden data on start and stop of treatments, imaging, prostate specific antigen, clinical assessment of progression and patient reported outcome measures (PROM) are registered from initiation of hormonal treatment. Data are displayed in a graph to inform clinical decisions for individual patients. For research, data in PPC are linked to PCBaSe with information from NPCR and a number of health care registers.Results: In December 2019, 7 882 men had been registered in PPC out of whom 3 912 had reached the CRPC state. Median time to start of androgen receptor targeted drugs (ART) from start of ADT was 4 years (interquartile range IQR 6) for men with primary ADT, and 9 years (IQR 6) and for men with secondary ADT. Out of all men in PCBaSe with a prescription for ART in 2016-2017, PPC captured 1 480/4 055 (36%). There were small differences between men registered/not registered in PPC for cancer characteristics, primary treatment, comorbidity, and time on ADT before start of ART.Conclusion: In PPC, use and effects of novel therapies for advanced Pca are assessed in a real-life setting. PPC data are used as a decision aid, for quality assurance, and in research.

Comparative Effectiveness of Different Radical Radiotherapy Treatment Regimens for Prostate Cancer: A Population-Based Cohort Study.

BACKGROUND: It is unclear which radiotherapy technique and dose fractionation scheme is most effective in decreasing the risk of prostate cancer death. METHODS: We conducted a population-based cohort study among 15 164 men in the Prostate Cancer database Sweden (version 4.0) treated with primary radical radiotherapy for prostate cancer in Sweden from 1998 to 2016. We calculated hazard ratios with 95% confidence intervals (CIs) of the association between the following exposure groups and outcome: conventionally fractionated external beam radiotherapy (EBRT) to 78 Gy (39 × 2 Gy), EBRT combined with high dose-rate brachytherapy (HDR-BT) (25 × 2 Gy + 2 × 10 Gy), conventionally fractionated EBRT to 70 Gy (35 × 2 Gy), and moderately hypofractionated (M-HF) dose-escalated EBRT (29 × 2.5 Gy or 22 × 3 Gy). RESULTS: Of the men, 7296 received conventionally fractionated EBRT to 78 Gy, 4657 EBRT combined with HDR-BT, 1672 conventionally fractionated EBRT to 70 Gy, and 1539 M-HF EBRT. Using EBRT to 78 Gy as the reference, the multivariable hazard ratios (95% CIs) of prostate cancer death was 0.64 (0.53 to 0.78) for EBRT combined with HDR-BT, 1.00 (0.80 to 1.27) for EBRT to 70 Gy, and 1.51 (0.99 to 2.32) for M-HF EBRT. The multivariable hazard ratios (95% CIs) for death from any cause were 0.79 (0.71 to 0.88), 0.99 (0.87 to 1.14), and 1.12 (0.88 to 1.42), respectively. The lower risk of prostate cancer death comparing EBRT combined with HDR-BT with conventionally fractionated EBRT to 78 Gy was more pronounced for men with high-risk or poorly differentiated tumors. CONCLUSIONS: In this study, EBRT combined with HDR-BT was the most effective radiotherapy treatment regimen, especially for poorly differentiated tumors. Randomized trials comparing EBRT combined with HDR-BT with dose-escalated EBRT should be a priority.

Radical radiotherapy for prostate cancer: patterns of care in Sweden 1998-2016.

Introduction: Radiotherapy is an established treatment option for prostate cancer (PCa), both as primary treatment and secondary treatment after radical prostatectomy (RP). Since 1998, detailed data on radiotherapy delivered to Swedish men with PCa (e.g. treatment modalities, absorbed doses, fractionation) have been collated within PCa data Base Sweden (PCBaSe). This study reports patterns of radical radiotherapy for PCa in Sweden over the past two decades.Materials and methods: All men with non-metastatic PCa (1998-2016) who received external beam radiotherapy (EBRT) or high or low dose-rate brachytherapy (HDR-BT/LDR-BT) were identified in PCBaSe. Analyses included: trends in radiation techniques, fractionation patterns and total doses over time; PCa-specific survival comparing treatment in 2007-2017 with 1998-2006; and regional variation in type of primary radiotherapy.Results: About 20,876 men underwent primary radiotherapy. The main treatment modalities include conventionally fractionated (2.0 Gy/fraction) EBRT (51%), EBRT with HDR-BT boost (27%) and hypofractionated (>2.4 Gy/fraction) EBRT (11%). EBRT with photon or proton boost and HDR-BT and LDR-BT monotherapies were each used minimally. Use of dose-escalated EBRT (>74 Gy) and moderate hypofractionation increased over time, while use of HDR-BT declined. Considerable regional variation in treatment modalities was apparent. Risk of PCa death following primary radiotherapy had declined for intermediate-risk (HR: 0.60; 95%CI 0.47-0.87) and high-risk PCa (HR: 0.72; 95%CI 0.61-0.86).Discussion: Increased use of dose escalation and hypofractionated EBRT has occurred in Sweden over the past two decades, reflecting current evidence and practice guidelines. Disease-specific outcomes have also improved. Data collected in PCBaSe provide an excellent resource for further research into RT use in PCa management.

Temporal changes in survival in men with de novo metastatic prostate cancer: nationwide population-based study.

Background: There have been large changes in the pattern of detection, work-up and treatment of men with prostate cancer during the last two decades. Therefore, we aimed to investigate temporal changes in survival in men with metastatic prostate cancer.Methods: Population-based cohort study in Prostate Cancer data Base Sweden of 13,709 men with de novo metastatic prostate cancer diagnosed between 1998 and 2015. Overall survival in four calendar periods were compared by the use of Kaplan-Meier analyses and Cox regression models including age at diagnosis, T stage and serum levels of prostate-specific antigen (PSA).Results: Between 1998-2001 and 2010-2015, median survival increased with 6 months for all men. The largest increase in survival was 14 months in men age 60-69 at diagnosis and in multivariable analysis risk of death decreased for men diagnosed in 2010-2015 compared to 1998-2001, hazard ratio (HR) 0.77 (95% CI: 0.68-0.86). The median PSA at date of diagnosis decreased with 46% from 181 ng/mL in 1998 to 98 ng/mL in 2015.Conclusions: There was an increase in survival among men with de novo metastatic prostate cancer in Sweden between 1998 and 2015. This increase was due to a decreased cancer extent indicated by lower PSA levels with ensuing longer lead times and speculatively also due to an increased use of chemotherapy in the latest time period. Given the increasing use of systemic treatment for advanced prostate cancer, our results are likely heralding larger increases in survival in men with metastatic prostate cancer in the near future.

Nationwide population-based study on the use of novel antiandrogens in men with prostate cancer in Sweden.

OBJECTIVES: The aim of this study was to examine the use of abiraterone and enzalutamide, two oral novel antiandrogens (NOVAs), in men with prostate cancer (PCa) in Sweden. MATERIALS AND METHODS: This cross-sectional study investigated filled prescriptions for NOVAs recorded in the Swedish Prescribed Drug Register between July 2015 and April 2016. Associations between age, comorbidity, educational level, marital status and county of residence and filled prescriptions were analyzed in the National Prostate Cancer Register (NPCR) and other health population-based registers, using multivariable logistic regression. RESULTS: Of 91,209 men, 1650 (2%) had at least one prescription filled for NOVAs, of whom 1350 (82%) had high-risk or metastatic PCa at diagnosis.. Of 1914 men with M1 disease and a high probability of castration-resistant prostate cancer (CRPC), 22% had a prescription for NOVAs at a median 3 years after the date of diagnosis. At multivariable logistic regression analysis,, the likelihood of NOVA use was lower in older men [age >80 vs <70 years: odds ratio (OR) 0.23, 95% confidence interval (CI) 0.15-0.35] and in men with lower educational level (high vs low education: OR 1.64, 95% CI 1.23-2.20). There was up to a five-fold difference in the use of NOVAs between county councils. CONCLUSIONS: Less than one-third of potentially eligible men with CRPC received NOVAs in 2015-2016. There were large differences in use according to age and region of residence, indicating that efforts are needed to improve equal access to novel cancer drugs.

Castration is a prerequisite for the inhibitory effect of metronomic chemotherapy on the growth of experimental castration-resistant prostate cancer.

BACKGROUND: Low-dose metronomic chemotherapy (LDMC) is an alternative for treatment of patients with late-stage prostate cancer (PC) not susceptible to regular chemotherapy due to its severe side effects. The exact working mechanisms of LDMC have not been established, although anti-angiogenic effects have been identified. In PC, several studies show clinical effects from LDMC but the mode of action and the role of androgen signaling for its effect are not known. In this study, we used a xenograft model to evaluate the effect of LDMC on PC growth in relation to androgen deprivation. MATERIAL AND METHODS: Subcutaneous human castration-resistant PC xenografts were treated with LDMC using cyclophosphamide (CPA). Treatment effect was compared to treatment with maximum tolerated dose (MTD) and also between intact and castrated mice. Microvessel density (MVD), and factors important for angiogenesis were analyzed with immunohistochemistry and real-time-PCR. RESULTS: Tumors treated with LDMC were 50% smaller than untreated controls. Tumors in non-castrated mice were not affected by LDMC, but in an androgen receptor (AR) negative tumor model, tumor inhibiting effect were seen in both intact and castrated animals, indicating mechanism via AR. MTD resulted in similar growth inhibition as LDMC in castrated mice, but resulted in severe weight loss. Despite that LDMC induced TSP1 mRNA expression, and the hypoxic area in the tumors was slightly increased, no decrease in MVD was detected. CONCLUSIONS: This study shows that a low-dose metronomic scheduling of CPA was as efficient as MTD treatment, and resulted in fewer side effects. It also demonstrates that a functional androgen signaling axis inhibits this effect despite the castration-resistance of the tumor cells. The anti-angiogenic nature of the effect of LDMC could not be confirmed and further studies to elucidate the working mechanism for treatment response are needed.

Prognostic significance and biopsy characteristics of prostate cancer with seminal vesicle invasion on radical prostatectomy: a nationwide population-based study.

The objective of this study was to evaluate the prognostic significance of seminal vesicle invasion (SVI, pT3b) compared with extraprostatic extension (EPE) alone (pT3a) after radical prostatectomy, and to correlate pre-operative biopsy pathology with SVI and EPE. The National Prostate Cancer Register includes all prostate cancers diagnosed in Sweden. We analysed 4063 cases with stage category pT3a and 1371 cases with pT3b at radical prostatectomy between 2000 and 2012. Associations between pT3a and pT3b and progression were evaluated and adjusted for year, age, biopsy grade and s-PSA. Needle biopsy findings in these stages were compared. Patients with pT3b (n=1371) had a higher risk of death from prostate cancer (HR 2.3, 95% CI 1.5-3.3, p<0.001) and death from any cause (HR 1.5, 95% CI 1.2-1.8, p<0.001) than those with pT3a (n=4063). They were also more likely to be treated with post-operative radiotherapy (HR 1.5, 95% CI 1.4-1.7, p<0.001) or androgen deprivation therapy (HR 3.0, 95% CI 2.5-3.7, p<0.001), indicating clinical progression. Yet, disease-specific survival of patients with stage pT3b was 94% after 6 years. Median cancer extent in pre-operative biopsies of pT3a and pT3b was 14 and 24 mm (p<0.001), number of positive cores was four and five, (p<0.001) and biopsy Gleason score was 8-10 in 11.6% and 27.3%, respectively (p<0.001). SVI of prostate cancer is associated with worse outcome after radical prostatectomy than EPE alone. However, few patients with SVI die within 6 years from surgery, suggesting that radical prostatectomy may be curative in locally advanced cancers.

[Prostate cancer units ­ hubs in the future care of men with prostate cancer]. / Prostatacancercentrum ­ navet i framtidens prostatacancersjukvård - En vision som är i linje med det nationella vårdprogrammets riktlinjer.

Prostate cancer units - hubs in the future care of men with prostate cancer Prostate cancer is the most common form of cancer in Sweden. The past decade has seen a tremendous development of new methods for diagnosing, staging, treating and rehabilitating men with suspicious or confirmed prostate cancer. This development necessitates a multidisciplinary and multiprofessional approach to the management of men with suspicious or confirmed prostate cancer. A recent survey showed that currently few Swedish men with prostate cancer receive the quality of care that is outlined in the national clinical guidelines. Specialised prostate cancer units are increasingly common in Europe, but as yet there are no such units in Sweden. We believe that the creation of prostate cancer units in Sweden would be an essential step forward, towards an improved future care of men with prostate cancer.

Long-term adverse effects after curative radiotherapy and radical prostatectomy: population-based nationwide register study.

OBJECTIVE: The aim of this study was to assess the risk of serious adverse effects after radiotherapy (RT) with curative intention and radical prostatectomy (RP). MATERIALS AND METHODS: Men who were diagnosed with prostate cancer between 1997 and 2012 and underwent curative treatment were selected from the Prostate Cancer data Base Sweden. For each included man, five prostate cancer-free controls, matched for birth year and county of residency, were randomly selected. In total, 12,534 men underwent RT, 24,886 underwent RP and 186,624 were controls. Adverse effects were defined according to surgical and diagnostic codes in the National Patient Registry. The relative risk (RR) of adverse effects up to 12 years after treatment was compared to controls and the risk was subsequently compared between RT and RP in multivariable analyses. RESULTS: Men with intermediate- and localized high-risk cancer who underwent curative treatment had an increased risk of adverse effects during the full study period compared to controls: the RR of undergoing a procedures after RT was 2.64 [95% confidence interval (CI) 2.56-2.73] and after RP 2.05 (95% CI 2.00-2.10). The risk remained elevated 10-12 years after treatment. For all risk categories of prostate cancer, the risk of surgical procedures for urinary incontinence was higher after RP (RR 23.64, 95% CI 11.71-47.74), whereas risk of other procedures on the lower urinary tract and gastrointestinal tract or abdominal wall was higher after RT (RR 1.67, 95% CI 1.44-1.94, and RR 1.86, 95% CI 1.70-2.02, respectively). CONCLUSION: The risk of serious adverse effects after curative treatment for prostate cancer remained significantly elevated up to 12 years after treatment.

Dashboard report on performance on select quality indicators to cancer care providers.

OBJECTIVE: Cancer quality registers are attracting increasing attention as important, but still underutilized sources of clinical data. To optimize the use of registers in quality assurance and improvement, data have to be rapidly collected, collated and presented as actionable, at-a-glance information to the reporting departments. This article presents a dashboard performance report on select quality indicators to cancer care providers. MATERIALS AND METHODS: Ten quality indicators registered on an individual patient level in the National Prostate Cancer Register of Sweden and recommended by the National Prostate Cancer Guidelines were selected. Data reported to the National Prostate Cancer Register are uploaded within 24 h to the Information Network for Cancer Care platform. Launched in 2014, "What''s Going On, Prostate Cancer" provides rapid, at-a-glance performance feedback to care providers. RESULTS: The indicators include time to report to the National Prostate Cancer Register, waiting times, designated clinical nurse specialist, multidisciplinary conference, adherence to guidelines for diagnostic work-up and treatment, and documentation and outcome of treatment. For each indicator, three performance levels were defined. CONCLUSION: What's Going On, a dashboard performance report on 10 selected quality indicators to cancer care providers, provides an example of how data in cancer quality registers can be transformed into condensed, at-a-glance information to be used as actionable metrics for quality assurance and improvement.

Bone Scan Index as an Imaging Biomarker in Metastatic Castration-resistant Prostate Cancer: A Multicentre Study Based on Patients Treated with Abiraterone Acetate (Zytiga) in Clinical Practice.

BACKGROUND: Abiraterone acetate (AA) prolongs survival in metastatic castration-resistant prostate cancer (mCRPC) patients. To measure treatment response accurately in bone, quantitative methods are needed. The Bone Scan Index (BSI), a prognostic imaging biomarker, reflects the tumour burden in bone as a percentage of the total skeletal mass calculated from bone scintigraphy. OBJECTIVE: To evaluate the value of BSI as a biomarker for outcome evaluation in mCRPC patients on treatment with AA according to clinical routine. DESIGN, SETTING, AND PARTICIPANTS: We retrospectively studied 104 mCRPC patients who received AA following disease progression after chemotherapy. All patients underwent whole-body bone scintigraphy before and during AA treatment. Baseline and follow-up BSI data were obtained using EXINI BoneBSI software (EXINI Diagnostics AB, Lund, Sweden). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Associations between change in BSI, clinical parameters at follow-up, and overall survival (OS) were evaluated using the Cox proportional hazards regression models and Kaplan-Meier estimates. Discrimination between variables was assessed using the concordance index (C-index). RESULTS AND LIMITATIONS: Patients with an increase in BSI at follow-up of at most 0.30 (n=54) had a significantly longer median survival time than those with an increase of BSI >0.30 (n=50) (median: 16 vs 10 mo; p=0.001). BSI change was also associated with OS in a multivariate Cox analysis including commonly used clinical parameters for prognosis (C-index=0.7; hazard ratio: 1.1; p=0.03). The retrospective design was a limitation. CONCLUSIONS: Change in BSI was significantly associated with OS in mCRPC patients undergoing AA treatment following disease progression in a postchemotherapy setting. BSI may be a useful imaging biomarker for outcome evaluation in this group of patients, and it could be a valuable complementary tool in monitoring patients with mCRPC on second-line therapies. PATIENT SUMMARY: Bone Scan Index (BSI) change is related to survival time in metastatic castration-resistant prostate cancer (mCRPC) patients on abiraterone acetate. BSI may be a valuable complementary decision-making tool supporting physicians monitoring patients with mCRPC on second-line therapies.

Undertreatment of Men in Their Seventies with High-risk Nonmetastatic Prostate Cancer.

BACKGROUND: Many elderly men with high-risk nonmetastatic prostate cancer (HRnMPCa) do not receive radical treatment, despite the high mortality associated with conservative management. OBJECTIVE: To investigate how age and comorbidity affect treatment of men with HRnMPCa. DESIGN, SETTING, AND PARTICIPANTS: This was an observational nationwide register study during 2001-2012. We identified 19 190 men of <80 yr of age diagnosed with HRnMPCa in the National Prostate Cancer Register of Sweden and 95 948 age-matched men without prostate cancer in the register of the total population. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The outcome was the proportion of men with HRnMPCa receiving radical treatment (radical prostatectomy or radiotherapy). Vital status and the Charlson comorbidity index (CCI) were obtained from nationwide registers. The 10-yr survival of men without prostate cancer, stratified by age and CCI, was used as a measure of the life expectancy of the men with prostate cancer. RESULTS AND LIMITATIONS: The proportions receiving radical treatment varied with life expectancy among men younger than 70 yr, whereas use of these treatments did not match the long life expectancy of men in their seventies with CCI 0-1. Only 10% of men aged 75-80 yr with CCI 0 received radical treatment despite 52% probability of 10-yr life expectancy, compared with approximately half of the men younger than 70 yr with a similar life expectancy. The use of radical treatment for HRnMPCa increased with time in all Swedish counties, but a threefold difference between counties remained in 2009-2012 for patients aged 70-80 yr with CCI 0-1. Uncertain external validity is a study limitation, and the impact of physician versus patient preferences on treatment selection could not be assessed. CONCLUSIONS: Otherwise healthy men in their seventies with HRnMPCa were less likely to receive radical treatment than younger men with a similar life expectancy, although increasing use of radical treatment was observed during the study period. Our findings highlight the need for improved methods for clinical decision-making, including improved assessment of life expectancy. PATIENT SUMMARY: We performed a nationwide register study that showed that many healthy men in their seventies live for at least another 10 yr. Despite this long life expectancy, men in their seventies with high-risk nonmetastatic prostate cancer were often not treated with radical prostatectomy or radiotherapy, possibly because their life expectancy was underestimated. Our study highlights the need for improved clinical decision-making, which should incorporate an assessment of the patient's life expectancy.

Localized expression of angiopoietin 1 and 2 may explain unique characteristics of the rat testicular microvasculature.

The testicular vasculature is unique in several ways. The unfenestrated endothelial cells constitute one part of the blood-testis barrier, and testicular microvessels are normally resistant to inflammation mediators. At the same time that angiogenic factors and inflammation mediators are constitutively produced, the proportion of proliferating endothelial cells is considerably higher than in other organs, but new blood vessels are not formed. Hormonal stimulation of the testis with hCG increase endothelial cell proliferation, vascular permeability, and sensitivity to locally injected inflammation mediators. In the present study, we examined whether local expression of angiopoietin (ang) 1, an inhibitor of vascular leakage and sprouting angiogenesis, and its antagonist, ang 2, could be involved in establishing this vascular phenotype. Using reverse transcription-polymerase chain reaction and immunohistochemistry, we demonstrate that testicular vascular endothelial growth factor-A (VEGF-A), ang 1, ang 2, and the ang-receptor tie 2 are expressed in the testis and that hormonal stimulation with hCG is accompanied by increased expression of VEGF-A and ang 2. The ang 1 protein is expressed in testicular microvessels under basal conditions, and it is largely unaffected after hCG stimulation. Expression of ang 2 in microvessels, in contrast, is low under basal conditions and is up-regulated by hCG. Intratesticular injection of human recombinant ang 1 protein inhibits hCG-induced increase in vascular permeability. Injection of ang 2 in the testis increases endothelial cell proliferation and the volume of the interstitial space. We therefore suggest that ang 1 stabilizes testicular microvessels under basal conditions and that a shift in this balance caused by increased ang 2, together with increased VEGF-A, allows vascular leakage, high endothelial cell proliferation, and presumably, vascular growth after hormonal stimulation.