Prostate-specific antigen-based screening for prostate cancer: Evidence, controversies and future perspectives

Latent prostate cancer among Japanese males: a bibliometric study of autopsy reports from 1980-2016

Prostate cancer is one of the most common malignancies, but a substantial portion remains latent throughout the patients' lifetime. Analysis of temporal change in the latent prostate cancer pool would be beneficial for clinical decision-making, but longitudinal autopsy studies are rare. We conducted a hand-search of the Annual of Pathological Autopsy Cases in Japan from 1980 to 2016 for cases of latent prostate cancer. Of 570 997 males aged 30 or older, latent prostate cancer was detected in 12 562 patients (2.2%). Proportion of detected cases correlated strongly with 'aging rate', the percentage of population aged 65 or older (squared Pearson's correlation coefficient r2 = 0.972, P value <0.0001). Temporal increase in proportion was also seen in each age group as well. This continuous growth reinforces evidence from past Japanese reports on latent prostate cancer. The rapidly rising ageing rate of Japan may forecast further increase in the latent prostate cancer pool moving forward.

Screening for prostate cancer: History, evidence, controversies and future perspectives toward individualized screening

Differences in the incidence and mortality rate of prostate cancer between the USA and Japan have been decreasing over time, and were only twofold in 2017. Therefore, countermeasures against prostate cancer could be very important not only in Western countries, but also in developed Asian countries. Screening for prostate cancer in the general population using transrectal ultrasonography, digital rectal examination and/or prostate acid phosphatase began in Japan in the early 1980s, and screening with prostate-specific antigen and digital rectal examination has been widespread in the USA since the late 1980s. Large- and mid-scale randomized controlled trials on screening for prostate cancer began around 1990 in the USA, Canada and Europe. However, most of these studies failed as randomized controlled trials because of high contamination in the control arm, low compliance in the screening arm or insufficient screening setting about screening frequency and/or biopsy indication. The best available level 1 evidence is data from the European Randomized Study of Screening for Prostate Cancer and the Göteborg screening study. However, several non-urological organizations and lay media around the world have mischaracterized the efficacy of prostate-specific antigen screening. To avoid long-term confusion about screening for prostate cancer, leading professional urological organizations, including the Japanese Urological Association, are moving toward the establishment of an optimal screening system that minimizes the drawbacks of overdetection, overtreatment and loss of quality of life due to treatment, and maximizes reductions in the risk of death as a result of prostate cancer and the development of metastatic prostate cancer.

Epidemiology of prostate cancer in Asian countries

The incidence of prostate cancer has been increasing worldwide in recent years. The GLOBOCAN project showed that prostate cancer was the second most frequently diagnosed cancer and the fifth leading cause of cancer mortality among men worldwide in 2012. This trend has been growing even in Asian countries, where the incidence had previously been low. However, the accuracy of data about incidence and mortality as a result of prostate cancer in some Asian countries is limited. The cause of this increasing trend is multifactorial. One possible explanation is changes in lifestyles due to more Westernized diets. The incidence is also statistically biased by the wide implementation of early detection systems and the accuracy of national cancer registration systems, which are still immature in most Asian countries. Mortality rate decreases in Australia, New Zealand and Japan since the 1990s are possibly due to the improvements in treatment and/or early detection efforts employed. However, this rate is increasing in the majority of other Asian countries. Studies of latent and incidental prostate cancer provide less biased information. The prevalence of latent and incidental prostate cancer in contemporary Japan and Korea is similar to those in Western countries, suggesting the influence of lifestyle changes on carcinogenesis. Many studies reported evidence of both congenital and acquired risk factors for carcinogenesis of prostate cancer. Recent changes in the acquired risk factors might be associated with the increasing occurrence of prostate cancer in Asian countries. This trend could continue, especially in developing Asian countries.

Prostate-specific antigen-based population screening for prostate cancer: current status in Japan and future perspective in Asia

In Western countries, clinical trials on prostate cancer screening demonstrated a limited benefit for patient survival. In the Asia-Pacific region, including Japan, the rate of prostate-specific antigen (PSA) testing remains very low compared with Western countries, and the benefits of population-based screening remain unclear. This review describes the current status of population screening and diagnosis for prostate cancer in Japan and discusses the efficacy of population screening for the Asian population. Since the 1990s, screening systems have been administered by each municipal government in Japan, and decreases in the prostate cancer mortality rate are expected in some regions where the exposure rate to PSA screening has increased markedly. A population-based screening cohort revealed that the proportion of metastatic disease in cancer detected by screening gradually decreased according to the increased exposure rate, and a decreasing trend in the proportion of cancer with high serum PSA levels after population screening was started. The prognosis of the prostate cancer detected by population screening was demonstrated to be more favorable than those diagnosed outside of the population screening. Recent results in screening cohorts demonstrated the efficacy of PSA. These recent evidences regarding population-based screening in Japan may contribute to establishing the optimal prostate cancer screening system in Asian individuals.

Decreasing trend in prostate cancer with high serum prostate-specific antigen levels detected at first prostate-specific antigen-based population screening in Japan

To clarify the recent trends in prostate-specific antigen (PSA) distribution in men in Japan, we analyzed the PSA distributions of men undergoing PSA-based population screening. We summarized the annual individual data of PSA-based population screening in Kanazawa, Japan, from 2000 to 2011, and analyzed baseline serum PSA values of the participants at the first population screening. Serum PSA distributions were estimated in all participants and those excluding prostate cancer patients according to age. From 2000 to 2011, 19 620 men participated aged 54–69 years old in this screening program. Mean baseline serum PSA level of all participants at the first screening was 2.64 ng ml⁻¹ in 2000, and gradually decreased to approximately 1.30 ng ml⁻¹ in 2006. That of participants excluding prostate cancer patients was 1.46 ng ml⁻¹ in 2000, and there was no remarkable change during the study period. The 95^th percentiles in the participants excluding prostate cancer patients detected at the first population screening of men aged 54–59, 60–64, and 65–69 years old were 2.90, 3.60, and 4.50 ng ml⁻¹, respectively. After the commencement of population screening, the proportion of prostate cancer patients with high serum PSA levels decreased. However, there were no changes in serum PSA levels in men without prostate cancer. Age-specific PSA reference level of men without prostate cancer in Japan was similar to that in China and Korea.

Cumulative probability of prostate cancer detection using the international prostate symptom score in a prostate-specific antigen-based population screening program in Japan

The International Prostate Symptom Score (IPSS) is often used as an interview sheet for assessing lower urinary tract symptoms (LUTS) at the time of prostate-specific antigen (PSA) testing during population-based screening for prostate cancer. However, the relationship between prostate cancer detection and LUTS status remains controversial. To elucidate this relationship, the cumulative probability of prostate cancer detection using IPSS in biopsy samples from patients categorized by serum PSA levels was investigated. The clinical characteristics of prostate cancer detected using IPSS during screening were also investigated. A total of 1,739 men aged 54-75 years with elevated serum PSA levels who completed the IPSS questionnaire during the initial population screening in Kanazawa City, Japan and underwent systematic transrectal ultrasonography-guided prostate biopsy between 2000 and 2013 were enrolled in the present study. Of the 1,739 men, 544 (31.3%) were diagnosed with prostate cancer during the observation period. The probability of cancer detection at 3 years in the entire study population was 27.4% and 32.7% for men with IPSS ≤ 7 and those with IPSS ≥ 8, respectively; there was no statistically significant difference between groups. In men with serum PSA levels of 6.1 to 12.0 ng/ mL at initial screening, the probability of cancer detection was significantly higher in men with IPSS ≤ 7 than in those with IPSS ≥ 8. There were no significant differences in clinical characteristics between groups of patients stratified by IPSS. These findings indicate that the use of IPSS for LUTS status evaluation may be useful for prostate cancer detection in the limited range of serum PSA levels.

Information of prostate biopsy positive core: does it affect MR detection of prostate cancer on using 3T-MRI?

OBJECTIVE

We assessed which information from a prostate biopsy had the strongest relationship with prostate cancer detection by 3T-MRI.

MATERIALS AND METHODS

Sixty-one consecutive patients with biopsy-proven prostate cancer who underwent 3T-MRI before biopsy were enrolled in this retrospective study. Two radiologists independently reviewed T2-weighted and diffusion-weighted images. When the cancer lesions were revealed by biopsy and MRI depicted them at corresponding sites, we classified these lesions as MRI-detectable cancer. If the cancer lesions were revealed by biopsy, but any cancers had not been detected, we classified these lesions as MRI-undetectable cancer. We compared the Gleason score (GS), cancer ratio (CaR) and cancer length (CaL) from core biopsies between the two groups.

THE RESULTS

GS, CaR and CaL differed significantly between the MRI-detectable group (N = 70), and the MRI-undetectable group (N = 73). 3T-MRI could detect cancer cores with a sensitivity of 90.5% in cores with CaR ≥ 60%, and with a sensitivity of 81.8% in those with CaL ≥ 5 mm. Receiver operating characteristic analysis showed that CaR (P = 0.006) and CaL (P = 0.010) significantly associated with the prostate cancer detection using MRI rather than GS.

CONCLUSION

CaR and CaL from the core biopsies showed a stronger relationship to detection of the prostate cancer on 3T-MRI than the GS did.

The C-terminal fragment of prostate-specific antigen, a 2331 Da peptide, as a new urinary pathognomonic biomarker candidate for diagnosing prostate cancer

Background and Objectives

Prostate cancer (PCa) is one of the most common cancers and leading cause of cancer-related deaths in men. Mass screening has been carried out since the 1990s using prostate-specific antigen (PSA) levels in the serum as a PCa biomarker. However, although PSA is an excellent organ-specific marker, it is not a cancer-specific marker. Therefore, the aim of this study was to discover new biomarkers for the diagnosis of PCa.

Materials and Methods

We focused on urine samples voided following prostate massage (digital rectal examination [DRE]) and conducted a peptidomic analysis of these samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MSⁿ). Urinary biomaterials were concentrated and desalted using CM-Sepharose prior to the following analyses being performed by MALDI-TOF/MSⁿ: 1) differential analyses of mass spectra; 2) determination of amino acid sequences; and 3) quantitative analyses using a stable isotope-labeled internal standard.

Results

Multivariate analysis of the MALDI-TOF/MS mass spectra of urinary extracts revealed a 2331 Da peptide in urine samples following DRE. This peptide was identified as a C-terminal PSA fragment composed of 19 amino acid residues. Moreover, quantitative analysis of the relationship between isotope-labeled synthetic and intact peptides using MALDI-TOF/MS revealed that this peptide may be a new pathognomonic biomarker candidate that can differentiate PCa patients from non-cancer subjects.

Conclusion

The results of the present study indicate that the 2331 Da peptide fragment of PSA may become a new pathognomonic biomarker for the diagnosis of PCa. A further large-scale investigation is currently underway to assess the possibility of using this peptide in the early detection of PCa.

Prostate cancer detection by prostate-specific antigen-based screening in the Japanese Hiroshima area shows early stage, low-grade, and low rate of cancer-specific death compared with clinical detection

INTRODUCTION

We investigate the effectiveness of prostate-specific antigen (PSA) screening for prostate cancer. We compare the characteristics of 2 sets of patients: (1) those in whom prostate cancer was detected via PSA screening (the PS group) and (2) those in whom prostate cancer was detected at the outpatient office (the non-PS group).

METHODS

Between 2002 and 2010, prostate cancer was detected in 315 patients by PSA screening. Their age, initial PSA level, pathological findings in biopsy specimens, clinical stage, and prognosis were compared with those of 497 prostate cancer patients diagnosed at the outpatient office of the Department of Urology, Hiroshima University, in the same period.

RESULTS

The rates of patients with initial PSA higher than 50 ng/mL, with a Gleason score of 8 or higher, and with clinical stage D were significantly lower in the PS group than those in the non-PS group. The 5-year overall survival and cancer-specific survival in the PS group was 91.3% and 98.2%, respectively; these results were significantly better than those in the non-PS group (86.4%, p = 0.0178, and 94.9%, p = 0.0112, respectively). A Cox hazard analysis showed that PSA screening was an independent predictive factor for cancer-specific survival.

CONCLUSIONS

Although our study is limited by its retrospective nature and small size, the present data indicate that prostate cancer detected in the PS group showed earlier stage, lower grade, and better prognosis than in the non-PS group.

Clinical characteristics and prostate-specific antigen kinetics of prostate cancer detected in repeat annual population screening in Japan

OBJECTIVES

To clarify the present status regarding repeat examination in the annual population screening system in Japan, and to analyze the clinical characteristics and prostate-specific antigen kinetics of prostate cancer detected in this setting.

METHODS

We summarized the annual individual data of prostate-specific antigen-based population screening in Kanazawa, Japan, and analyzed the prostate cancer detection rates at first and repeat screening. The clinical characteristics were compared between patients detected at first and repeat screening. The patients were classified according to favorable or unfavorable clinical characteristics of cancer, and prostate-specific antigen kinetics were compared between the two groups.

RESULTS

From 2000 to 2011, 19 620 men participated in this screening program, and a total of 59 019 screenings were carried out. The total annual numbers of examinees increased, and the annual rates of first examinees gradually decreased. The annual detection rates of cancer at total screening decreased in the second year. The annual detection rate at first screening was not different from that in the first year. The rate of patients with favorable cancer features was significantly higher among patients detected at repeat screening than at first screening. The rates of patients with high prostate-specific antigen velocity and low prostate-specific antigen doubling time were significantly higher in unfavorable than favorable cancer patients in repeat screening.

CONCLUSIONS

Repeat population screening could contribute to early detection of prostate cancer, and it seems that prostate-specific antigen kinetics might predict the cancer characteristics in repeat screening.

Difference in willingness-to-pay for prostate cancer screening between ill-informed and well-informed men: a contingent valuation survey

OBJECTIVES

To use a contingent valuation method to compare the willingness of well-informed and ill-informed men to pay for PSA screening. Prostate cancer screening by analysis of prostate-specific antigen (PSA) levels has recently been confirmed to reduce prostate cancer death. However, PSA screening is associated with considerable risks, and men should be well informed about the risks before deciding to undergo the test.

METHODS

A total of 1800 men aged 50-69 years old participated in an Internet-based, computer-assisted questionnaire survey. The subjects were randomly divided into 2 groups. Group 1 (n = 900) was provided with information about the procedure, detection rate, and mortality-reducing effects of PSA screening. Additional information was given to group 2 (n = 900), including the possibility of false-positive or false-negative results, the risks of close examination, and the possibility of overdiagnoses. The willingness to pay (WTP) was assessed using a double-bound dichotomous choice method.

RESULTS

The average WTP was significantly greater in group 1 than in group 2 ($31.1 vs $25.1, P < .01). Weibull regression analysis showed that patients with a history of receiving PSA screening or with greater incomes had a significantly greater WTP.

CONCLUSIONS

Although providing information on the risks of PSA screening significantly decreased men's WTP for such tests, the well-informed group was still willing to pay $25.1. These findings suggest that men can balance the potential disadvantages of PSA screening against its effectiveness in saving lives.

Updated Japanese Urological Association Guidelines on prostate-specific antigen-based screening for prostate cancer in 2010

The exposure rate of screening for prostate cancer using prostate-specific antigen (PSA) in Japan is still very low compared with that in the USA or western Europe. The mortality rate of prostate cancer will increase in the future and in 2020 it will be 2.8-fold higher than in 2000. Therefore, there is an urgent need to determine the best available countermeasures to decrease the rate of prostate cancer death. PSA screening, which can reduce the risk of death as a result of prostate cancer, should be offered to all men at risk of developing prostate cancer with fact sheets showing updated benefits and drawbacks of screening for prostate cancer.

Ligation of prostate cancer cell surface GRP78 activates a proproliferative and antiapoptotic feedback loop: a role for secreted prostate-specific antigen

GRP78, a well characterized chaperone in the endoplasmic reticulum, is critical to the unfolded protein response. More recently, it has been identified on the cell surface, where it has many roles. On cancer cells, it functions as a signaling receptor coupled to proproliferative/antiapoptotic and promigratory mechanisms. In the current study, we demonstrate that ligation of prostate cancer cell surface GRP78 by its natural ligand, activated α(2)-macroglobulin (α(2)M*), results in a 2-3-fold up-regulation in the synthesis of prostate-specific antigen (PSA). The PSA is secreted into the medium as an active proteinase, where it binds to native α(2)M. The resultant α(2)M·PSA complexes bind to GRP78, causing a 1.5-2-fold increase in the activation of MEK1/2, ERK1/2, S6K, and Akt, which is coupled with a 2-3-fold increase in DNA and protein synthesis. PSA is a marker for the progression of prostate cancer, but its mechanistic role in the disease is unclear. The present studies suggest that PSA may be involved in a signal transduction-dependent feedback loop, whereby it promotes a more aggressive behavior by human prostate cancer cells.

Pathological findings at radical prostatectomy in Japanese prospective active surveillance cohort

OBJECTIVES

The present study was carried out to analyze pathological features of prostatectomy specimens performed at different timing and trigger during active surveillance.

METHODS

One hundred and thirty-four patients that fit a selection condition similar to the so-called Hopkins' criteria were enrolled into the present study between January 2002 and December 2003. Patients were recommended to start curable treatment when they showed prostate-specific antigen-doubling time of 2 years or shorter or pathological progression at 1-year re-biopsy. Median observation period was 61 months.

RESULTS

Fourteen patients underwent radical prostatectomy immediately after enrollment (Group A) whereas 28 patients underwent radical prostatectomy after substantial periods of active surveillance (Group B). Of the 28 Group B, trigger of radical prostatectomy was on protocol in 17 patients (Group B1) whereas 11 patients underwent radical prostatectomy by their preference (Group B2). Upgrade from initial biopsy was observed in 43% of Group A and 68% of Group B. Upgrade was more frequently observed in Group B1 than B2 with border line significance (P = 0.075). Perineural infiltration and positive surgical margin rates of Group B1 were significantly higher than those of B2 (P < 0.05).

CONCLUSIONS

Unfavorable pathological features of surgical specimens were more frequently observed in patients who underwent radical prostatectomy due to short prostate-specific antigen-doubling time or biopsy findings than those who underwent radical prostatectomy because of other reasons including patients' preference. Rates of unfavorable pathological features at radical prostatectomy that deviate initial selection criteria was high enough to support integration of frequent biopsies into active surveillance program.