Objectives

To compare directly survival outcomes of primary androgen-deprivation therapy (PADT) in Japan, where this treatment is endorsed by guidelines, with outcomes in the USA, where it is not.

Patients and methods

Data were compared between men receiving PADT in the USA Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry and the Japanese Cancer of the Prostate (J-CaP) registry database. Competing risks regression was used to assess prostate cancer-specific mortality (CSM), adjusting for age, Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score, diagnosis year, and treatment type [combined androgen blockade (CAB) vs castration monotherapy], comorbidity, and practice type.

Results

Men on PADT in J-CaP (13 880 men) were older than those in CaPSURE (1633 men), and had higher-risk disease (mean J-CAPRA score 3.8 vs 2.1, P < 0.001). They more often received CAB: 66.9% vs 46.4% (P < 0.001). Despite different risk profiles between the cohorts, CSM was similar on univariate analysis (log-rank P = 0.88). On multivariable regression, the subhazard ratio for CSM was 0.52 for J-CaP vs CaPSURE (95% confidence interval 0.40-0.68).

Conclusions

Men on PADT in Japan have less than half the adjusted CSM than those in the USA. These findings support both existing guidelines endorsing PADT in Asia and discouraging its use in the West. Elucidating the reasons behind these substantial differences, which probably include both genetic and dietary/environmental factors, may help explain the varying epidemiology of prostate cancer on either side of the Pacific.

Purpose

Prostate cancer epidemiology has been marked overall by a downward risk migration over time. However, in some populations, both in the United States and abroad, many men are still diagnosed with high-risk and/or advanced disease. Primary androgen deprivation therapy (PADT) is frequently offered to these patients, and disease risk prediction is not well-established in this context. We compared risk features between large disease registries from the United States and Japan, and aimed to build and validate a risk prediction model applicable to PADT patients.

Methods

Data were analyzed from 13,740 men in the United States community-based Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry and 19,265 men in the Japan Study Group of Prostate Cancer (J-CaP) database, a national Japanese registry of men receiving androgen deprivation therapy. Risk distribution was compared between the two datasets using three well-described multivariable instruments. A novel instrument (Japan Cancer of the Prostate Risk Assessment [J-CAPRA]) was designed and validated to be specifically applicable to PADT patients, and more relevant to high-risk patients than existing instruments.

Results

J-CaP patients are more likely than CaPSURE patients to be diagnosed with high-risk features; 43% of J-CaP versus 5% of CaPSURE patients had locally advanced or metastatic disease that could not be stratified with the standard risk assessment tools. J-CAPRA--scored 0 to 12 based on Gleason score, prostate-specific antigen level, and clinical stage--predicts progression-free survival among PADT patients in J-CaP with a c-index of 0.71, and cancer-specific survival among PADT patients in CaPSURE with a c-index of 0.84.

Conclusion

The novel J-CAPRA is the first risk instrument developed and validated for patients undergoing PADT. It is applicable to those with both localized and advanced disease, and performs well in diverse populations.

Both clinical and preclinical studies have mostly shown beneficial effects for Phosphodiesterase-5 (PDE-5) inhibitors in the treatment of lower urinary tract symptoms. Molecular studies have consistently shown abundant PDE-5 expression in bladder smooth muscle. Data concerning urethral PDE-5 expression have been surprising because striated muscle was not only positively identified, but also found to express more PDE-5 than the smooth muscle. In the prostate, highly variable results have been obtained. For PDE-5 expression, the data have ranged from extremely low to highly abundant. PDE-5 has been found in the glandular epithelium, vascular smooth muscle, endothelium, and fibromuscular stroma.

Objectives To compare directly survival outcomes of primary androgen-deprivation therapy (PADT) in Japan, where this treatment is endorsed by guidelines, with outcomes in the USA, where it is not. Patients and Methods Data were compared between men receiving PADT in the USA Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry and the Japanese Cancer of the Prostate (J-CaP) registry database. Competing risks regression was used to assess prostate cancer-specific mortality (CSM), adjusting for age, Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score, diagnosis year, and treatment type [combined androgen blockade (CAB) vs castration monotherapy], comorbidity, and practice type. Results Men on PADT in J-CaP (13 880 men) were older than those in CaPSURE (1633 men), and had higher-risk disease (mean J-CAPRA score 3.8 vs 2.1, P < 0.001). They more often received CAB: 66.9% vs 46.4% (P < 0.001). Despite different risk profiles between the cohorts, CSM was similar on univariate analysis (log-rank P = 0.88). On multivariable regression, the subhazard ratio for CSM was 0.52 for J-CaP vs CaPSURE (95% confidence interval 0.40-0.68). Conclusions Men on PADT in Japan have less than half the adjusted CSM than those in the USA. These findings support both existing guidelines endorsing PADT in Asia and discouraging its use in the West. Elucidating the reasons behind these substantial differences, which probably include both genetic and dietary/environmental factors, may help explain the varying epidemiology of prostate cancer on either side of the Pacific.

This report summarizes the presentations and discussions that took place at the Sixth Joint Meeting of J-CaP and CaPSURE held in San Francisco, USA, in August 2012. The J-CaP and CaPSURE Joint Initiative was established in 2007 with the objective of analyzing, reviewing, comparing and contrasting data for prostate cancer patients from Japan and the USA within the two important large-scale, longitudinal, observational databases-J-CaP and CaPSURE. Since this initial collaboration between teams in the USA and Japan, the initiative has now expanded to include representatives of other Asian countries, several of whom have either established or are planning their own national prostate cancer databases. Several key topics were considered at this Sixth Joint Meeting including the current status of the J-CaP and CaPSURE databases and opportunities for collaboration with the more recently developed Asian prostate cancer databases. The latest comparative data from J-CaP and CaPSURE regarding outcomes following androgen deprivation therapy and combined androgen blockade were also reviewed. The possibility of a global chemoprevention trial to investigate the influence of soy isoflavones on prostate cancer incidence was considered. In addition, the ongoing debate regarding the role of screening and the use of active surveillance as a treatment option in the USA was discussed. The collaborators agreed that sharing of data and treatment practices on a global scale would undoubtedly benefit the clinical management of prostate cancer patients worldwide.

This report summarizes the presentations and discussions that took place at the Seventh Joint Meeting of the Korea-Japan Study Group of Prostate Cancer (K-J-CaP) and the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) held in Seoul, Korea, in September 2013. The original J-CaP and CaPSURE Joint Initiative has now been established since 2007 and since the initial collaboration between research teams in the United States (US) and Japan, the project has expanded to include several other Asian countries. The objective of the initiative is to analyze and compare data for prostate cancer patients in the participating countries, looking at similarities and differences in patient management and outcomes. Until now the focus has been primarily on data generated within J-CaP and CaPSURE, both large-scale, longitudinal, observational databases of prostate cancer patients in Japan and the US, respectively. This year's meeting was hosted for the first time in Korea which has recently established its own national database-K-CaP-to add to the wealth of data generated by J-CaP and CaPSURE. As a newly-developed database, K-CaP has also provided a valuable 'template' for other countries, such as China and Indonesia, planning to establish their own national databases and this will ultimately allow greater opportunities for international data comparisons. A range of topics was discussed at this Seventh Joint Meeting including comparison of outcomes following androgen deprivation therapy or radical prostatectomy in patients with localized prostate cancer, the use of active surveillance as a treatment option and the triggers for intervention when employing this regimen, patient quality of life during treatment, the impact of comorbidities on outcomes, and a comparison of recent outcomes data between J-CaP and CaPSURE. The participants recognized that prostate cancer was now a global disease and therefore major insights into understanding and improving the management of this condition would arise from global interactions such as this joint initiative.

The Asian Prostate Cancer (A-CaP) study is an Asia-wide initiative that was launched in December 2015 in Tokyo, Japan, with the objective of surveying information about patients who have received a histopathological diagnosis of prostate cancer (PCa) and are undergoing treatment and clarifying distribution of staging, the actual status of treatment choices, and treatment outcomes. The study aims to clarify the clinical situation for PCa in Asia and use the outcomes for the purposes of international comparison. Following the first meeting in Tokyo in December 2015, the second A-CaP meeting was held in Seoul, Korea, in September 2016. This, the third A-CaP meeting, was held on October 14, 2017, in Chiang Mai, Thailand, with the participation of members and collaborators from 12 countries and regions. In the meeting, participating countries and regions presented the current status of data collection, and the A-CaP office presented a preliminary analysis of the registered cases received from each country and region. Participants discussed ongoing challenges relating to data input and collection, institutional, and legislative issues that may present barriers to data sharing, and the outlook for further patient registrations through to the end of the registration period in December 2018. In addition to A-CaP-specific discussions, a series of special lectures were also delivered on the situation for health insurance in the United States, the correlation between insurance coverage and PCa outcomes, and the outlook for robotic surgery in the Asia-Pacific region. Members also confirmed the principles of authorship in collaborative studies, with a view to publishing original articles based on A-CaP data in the future.

The Asian Prostate Cancer (A-CaP) Study is an Asia-wide initiative that has been developed over the course of 2 years. The A-CaP Study is scheduled to begin in 2016, when each participating country or region will begin registration of newly diagnosed prostate cancer patients and conduct prognosis investigations. From the data gathered, common research themes will be identified, such as comparisons among Asian countries of background factors in newly diagnosed prostate cancer patients. This is the first Asia-wide study of prostate cancer and has developed from single country research efforts in this field, including in Japan and Korea. The inaugural Board Meeting of A-CaP was held on December 11, 2015 at the Research Center for Advanced Science and Technology, The University of Tokyo, attended by representatives of all participating countries and regions, who signed a memorandum of understanding concerning registration for A-CaP. Following the Board Meeting an A-CaP Launch Symposium was held. The symposium was attended by representatives of countries and regions participating in A-CaP, who gave presentations. Presentations and a keynote address were also delivered by representatives of the University of California San Francisco, USA, and the Peter MacCallum Cancer Centre, Australia, who provided insight and experience on similar databases compiled in their respective countries.