Transcriptome-wide association analysis identifies candidate susceptibility genes for prostate-specific antigen levels in men without prostate cancer.

Deciphering the genetic basis of prostate-specific antigen (PSA) levels may improve their utility for prostate cancer (PCa) screening. Using genome-wide association study (GWAS) summary statistics from 95,768 PCa-free men, we conducted a transcriptome-wide association study (TWAS) to examine impacts of genetically predicted gene expression on PSA. Analyses identified 41 statistically significant (p < 0.05/12,192 = 4.10 × 10-6) associations in whole blood and 39 statistically significant (p < 0.05/13,844 = 3.61 × 10-6) associations in prostate tissue, with 18 genes associated in both tissues. Cross-tissue analyses identified 155 statistically significantly (p < 0.05/22,249 = 2.25 × 10-6) genes. Out of 173 unique PSA-associated genes across analyses, we replicated 151 (87.3%) in a TWAS of 209,318 PCa-free individuals from the Million Veteran Program. Based on conditional analyses, we found 20 genes (11 single tissue, nine cross-tissue) that were associated with PSA levels in the discovery TWAS that were not attributable to a lead variant from a GWAS. Ten of these 20 genes replicated, and two of the replicated genes had colocalization probability of >0.5: CCNA2 and HIST1H2BN. Six of the 20 identified genes are not known to impact PCa risk. Fine-mapping based on whole blood and prostate tissue revealed five protein-coding genes with evidence of causal relationships with PSA levels. Of these five genes, four exhibited evidence of colocalization and one was conditionally independent of previous GWAS findings. These results yield hypotheses that should be further explored to improve understanding of genetic factors underlying PSA levels.

Performance of 4Kscore as a Reflex Test to Prostate-specific Antigen in the GÖTEBORG-2 Prostate Cancer Screening Trial.

BACKGROUND AND OBJECTIVE: We investigated whether adding 4Kscore as a reflex test to prostate-specific antigen (PSA) could improve the screening algorithm for prostate cancer (PC). METHODS: In the GÖTEBORG-2 PC screening trial, 38 000men (50-60 yr) were invited to PSA testing and, if elevated, followed by magnetic resonance imaging (MRI). For 571 men with PSA ≥3.0 ng/ml and evaluable outcomes, 4Kscore was calculated. The performance using a prespecified 4Kscore cutoff of 7.5% was evaluated. KEY FINDINGS AND LIMITATIONS: The area under the curve for 4Kscore to identify intermediate- and high-risk PC was 0.84 (95% confidence interval 0.79-0.89), and the positive predictive value, and negative predictive value were 15% (0.12-0.20) and 99% (97-100%), respectively. Of the 54 men diagnosed with intermediate- or high-grade PC, two had a 4Kscore cutoff below 7.5%, both with organ-confined intermediate-risk PC. Per 1000 men with elevated PSA, adding 4Kscore would have resulted in avoidance of MRI for 408 (41%) men, biopsies for 95 (28% reduction) men, and diagnosis of 23 low-grade cancers (23% reduction) while delaying the diagnosis of four men with intermediate-grade cancers (4%). CONCLUSIONS AND CLINICAL IMPLICATIONS: Including 4Kscore as a reflex test for men with elevated PSA reduces the need for MRI and biopsy markedly, and results in less overdiagnosis of low-grade PC at the cost of delaying the diagnosis of intermediate-grade PC in a few men. These results add further evidence for including new blood-based biomarkers in addition to PSA to improve the harm and benefit ratio of PC screening and reduce the need for resource-demanding MRI and biopsies. PATIENT SUMMARY: In this study, 4Kscore, a blood-based biomarker, as a reflex test for men with elevated prostate-specific antigen (PSA), reduces the need for magnetic resonance imaging and biopsy. These results support the inclusion of new blood-based biomarkers in addition to PSA.

Acoustic Enrichment of Heterogeneous Circulating Tumor Cells and Clusters from Metastatic Prostate Cancer Patients.

BACKGROUND: There are important unmet clinical needs to develop cell enrichment technologies to enable unbiased label-free isolation of both single cell and clusters of circulating tumor cells (CTCs) manifesting heterogeneous lineage specificity. Here, we report a pilot study based on the microfluidic acoustophoresis enrichment of CTCs using the CellSearch CTC assay as a reference modality. METHODS: Acoustophoresis uses an ultrasonic standing wave field to separate cells based on biomechanical properties (size, density, and compressibility), resulting in inherently label-free and epitope-independent cell enrichment. Following red blood cell lysis and paraformaldehyde fixation, 6 mL of whole blood from 12 patients with metastatic prostate cancer and 20 healthy controls were processed with acoustophoresis and subsequent image cytometry. RESULTS: Acoustophoresis enabled enrichment and characterization of phenotypic CTCs (EpCAM+, Cytokeratin+, DAPI+, CD45-/CD66b-) in all patients with metastatic prostate cancer and detected CTC-clusters composed of only CTCs or heterogeneous aggregates of CTCs clustered with various types of white blood cells in 9 out of 12 patients. By contrast, CellSearch did not detect any CTC clusters, but detected comparable numbers of phenotypic CTCs as acoustophoresis, with trends of finding a higher number of CTCs using acoustophoresis. CONCLUSION: Our preliminary data indicate that acoustophoresis provides excellent possibilities to detect and characterize CTC clusters as a putative marker of metastatic disease and outcomes. Moreover, acoustophoresis enables the sensitive label-free enrichment of cells with epithelial phenotypes in blood and offers opportunities to detect and characterize CTCs undergoing epithelial-to-mesenchymal transitioning and lineage plasticity.

Prostate Cancer Screening With PSA, Kallikrein Panel, and MRI: The ProScreen Randomized Trial.

Importance: Prostate-specific antigen (PSA) screening has potential to reduce prostate cancer mortality but frequently detects prostate cancer that is not clinically important. Objective: To describe rates of low-grade (grade group 1) and high-grade (grade groups 2-5) prostate cancer identified among men invited to participate in a prostate cancer screening protocol consisting of a PSA test, a 4-kallikrein panel, and a magnetic resonance imaging (MRI) scan. Design, Setting, and Participants: The ProScreen trial is a clinical trial conducted in Helsinki and Tampere, Finland, that randomized 61 193 men aged 50 through 63 years who were free of prostate cancer in a 1:3 ratio to either be invited or not be invited to undergo screening for prostate cancer between February 2018 and July 2020. Interventions: Participating men randomized to the intervention underwent PSA testing. Those with a PSA level of 3.0 ng/mL or higher underwent additional testing for high-grade prostate cancer with a 4-kallikrein panel risk score. Those with a kallikrein panel score of 7.5% or higher underwent an MRI of the prostate gland, followed by targeted biopsies for those with abnormal prostate gland MRI findings. Final data collection occurred through June 31, 2023. Main Outcomes and Measures: In descriptive exploratory analyses, the cumulative incidence of low-grade and high-grade prostate cancer after the first screening round were compared between the group invited to undergo prostate cancer screening and the control group. Results: Of 60 745 eligible men (mean [SD] age, 57.2 [4.0] years), 15 201 were randomized to be invited and 45 544 were randomized not to be invited to undergo prostate cancer screening. Of 15 201 eligible males invited to undergo screening, 7744 (51%) participated. Among them, 32 low-grade prostate cancers (cumulative incidence, 0.41%) and 128 high-grade prostate cancers (cumulative incidence, 1.65%) were detected, with 1 cancer grade group result missing. Among the 7457 invited men (49%) who refused participation, 7 low-grade prostate cancers (cumulative incidence, 0.1%) and 44 high-grade prostate cancers (cumulative incidence, 0.6%) were detected, with 7 cancer grade groups missing. For the entire invited screening group, 39 low-grade prostate cancers (cumulative incidence, 0.26%) and 172 high-grade prostate cancers (cumulative incidence, 1.13%) were detected. During a median follow-up of 3.2 years, in the group not invited to undergo screening, 65 low-grade prostate cancers (cumulative incidence, 0.14%) and 282 high-grade prostate cancers (cumulative incidence, 0.62%) were detected. The risk difference for the entire group randomized to the screening invitation vs the control group was 0.11% (95% CI, 0.03%-0.20%) for low-grade and 0.51% (95% CI, 0.33%-0.70%) for high-grade cancer. Conclusions and Relevance: In this preliminary descriptive report from an ongoing randomized clinical trial, 1 additional high-grade cancer per 196 men and 1 low-grade cancer per 909 men were detected among those randomized to be invited to undergo a single prostate cancer screening intervention compared with those not invited to undergo screening. These preliminary findings from a single round of screening should be interpreted cautiously, pending results of the study's primary mortality outcome. Trial Registration: ClinicalTrials.gov Identifier: NCT03423303.

Acoustic enrichment of heterogenous circulating tumor cells and clusters from patients with metastatic prostate cancer.

Background: There are important unmet clinical needs to develop cell enrichment technologies to enable unbiased label-free isolation of both single cell and clusters of circulating tumor cells (CTCs) manifesting heterogeneous lineage specificity. Here, we report a pilot study based on microfluidic acoustophoresis enrichment of CTCs using the CellSearch CTC assay as a reference modality. Methods: Acoustophoresis uses an ultrasonic standing wave field to separate cells based on biomechanical properties (size, density, and compressibility) resulting in inherently label-free and epitope-independent cell enrichment. Following red blood cell lysis and paraformaldehyde fixation, 6 mL of whole blood from 12 patients with metastatic prostate cancer and 20 healthy controls were processed with acoustophoresis and subsequent image cytometry. Results: Acoustophoresis enabled enrichment and characterization of phenotypic CTCs (EpCAM+, Cytokeratin+, DAPI+, CD45-/CD66b-) in all patients with metastatic prostate cancer and detected CTC-clusters composed of only CTCs or heterogenous aggregates of CTCs clustered with various types of white blood cells in 9 out of 12 patients. By contrast, CellSearch did not detect any CTC-clusters, but detected comparable numbers of phenotypic CTCs as acoustophoresis, with trends of finding higher number of CTCs using acoustophoresis. Conclusion: Our preliminary data indicate that acoustophoresis provides excellent possibilities to detect and characterize CTC-clusters as a putative marker of metastatic disease and outcomes. Moreover, acoustophoresis enables sensitive label-free enrichment of cells with epithelial phenotype in blood and offers opportunities to detect and characterize CTCs undergoing epithelial-to-mesenchymal transitioning and lineage plasticity.

Genome-wide association study of prostate-specific antigen levels in 392,522 men identifies new loci and improves cross-ancestry prediction.

We conducted a multi-ancestry genome-wide association study of prostate-specific antigen (PSA) levels in 296,754 men (211,342 European ancestry; 58,236 African ancestry; 23,546 Hispanic/Latino; 3,630 Asian ancestry; 96.5% of participants were from the Million Veteran Program). We identified 318 independent genome-wide significant (p≤5e-8) variants, 184 of which were novel. Most demonstrated evidence of replication in an independent cohort (n=95,768). Meta-analyzing discovery and replication (n=392,522) identified 447 variants, of which a further 111 were novel. Out-of-sample variance in PSA explained by our new polygenic risk score reached 16.9% (95% CI=16.1%-17.8%) in European ancestry, 9.5% (95% CI=7.0%-12.2%) in African ancestry, 18.6% (95% CI=15.8%-21.4%) in Hispanic/Latino, and 15.3% (95% CI=12.7%-18.1%) in Asian ancestry, and lower for higher age. Our study highlights how including proportionally more participants from underrepresented populations improves genetic prediction of PSA levels, with potential to personalize prostate cancer screening.

Free PSA and Clinically Significant and Fatal Prostate Cancer in the PLCO Screening Trial.

PURPOSE: We studied whether adding percent free PSA to total PSA improves prediction of clinically significant prostate cancer and fatal prostate cancer. MATERIALS AND METHODS: A total of 6,727 men within the intervention arm of PLCO (Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial) had baseline percent free PSA. Of this cohort, 475 had clinically significant prostate cancer and 98 had fatal prostate cancer. Cumulative incidence and Cox analyses were conducted to evaluate the association between percent free PSA/PSA and clinically significant prostate cancer/fatal prostate cancer. Harrell's C index evaluated predictive ability. Kaplan-Meier analysis assessed survival. RESULTS: Median follow-up was 19.7 years, median baseline PSA was 1.19 ng/mL, median percent free PSA was 18%. Cumulative incidence of fatal prostate cancer for men with baseline PSA ≥2 ng/mL and percent free PSA ≤10 was 3.2% and 6.1% at 15 and 25 years, respectively, compared to 0.03% and 1.1% for men with percent free PSA >25%. In younger men (55-64 years) with baseline PSA 2-10 ng/mL, C index improved from 0.56 to 0.60 for clinically significant prostate cancer and from 0.53 to 0.64 for fatal prostate cancer with addition of percent free PSA. In older men (65-74 years), C index improved for clinically significant prostate cancer from 0.60 to 0.66, with no improvement in fatal prostate cancer. Adjusting for age, digital rectal exam, family history of prostate cancer, and total PSA, percent free PSA was associated with clinically significant prostate cancer (HR 1.05, P < .001) per 1% decrease. Percent free PSA improved prediction of clinically significant prostate cancer and fatal prostate cancer for all race groups. CONCLUSIONS: In a large U.S. screening trial, the addition of percent free PSA to total PSA in men with baseline PSA ≥2 ng/mL improved prediction of clinically significant prostate cancer and fatal prostate cancer. Free PSA should be used to risk-stratify screening and decrease unnecessary prostate biopsies.

Genetically adjusted PSA levels for prostate cancer screening.

Prostate-specific antigen (PSA) screening for prostate cancer remains controversial because it increases overdiagnosis and overtreatment of clinically insignificant tumors. Accounting for genetic determinants of constitutive, non-cancer-related PSA variation has potential to improve screening utility. In this study, we discovered 128 genome-wide significant associations (P < 5 × 10-8) in a multi-ancestry meta-analysis of 95,768 men and developed a PSA polygenic score (PGSPSA) that explains 9.61% of constitutive PSA variation. We found that, in men of European ancestry, using PGS-adjusted PSA would avoid up to 31% of negative prostate biopsies but also result in 12% fewer biopsies in patients with prostate cancer, mostly with Gleason score <7 tumors. Genetically adjusted PSA was more predictive of aggressive prostate cancer (odds ratio (OR) = 3.44, P = 6.2 × 10-14, area under the curve (AUC) = 0.755) than unadjusted PSA (OR = 3.31, P = 1.1 × 10-12, AUC = 0.738) in 106 cases and 23,667 controls. Compared to a prostate cancer PGS alone (AUC = 0.712), including genetically adjusted PSA improved detection of aggressive disease (AUC = 0.786, P = 7.2 × 10-4). Our findings highlight the potential utility of incorporating PGS for personalized biomarkers in prostate cancer screening.

Transcriptome-Wide Association Analysis Identifies Novel Candidate Susceptibility Genes for Prostate-Specific Antigen Levels in Men Without Prostate Cancer.

Deciphering the genetic basis of prostate-specific antigen (PSA) levels may improve their utility to screen for prostate cancer (PCa). We thus conducted a transcriptome-wide association study (TWAS) of PSA levels using genome-wide summary statistics from 95,768 PCa-free men, the MetaXcan framework, and gene prediction models trained in Genotype-Tissue Expression (GTEx) project data. Tissue-specific analyses identified 41 statistically significant (p < 0.05/12,192 = 4.10e-6) associations in whole blood and 39 statistically significant (p < 0.05/13,844 = 3.61e-6) associations in prostate tissue, with 18 genes associated in both tissues. Cross-tissue analyses that combined associations across 45 tissues identified 155 genes that were statistically significantly (p < 0.05/22,249 = 2.25e-6) associated with PSA levels. Based on conditional analyses that assessed whether TWAS associations were attributable to a lead GWAS variant, we found 20 novel genes (11 single-tissue, 9 cross-tissue) that were associated with PSA levels in the TWAS. Of these novel genes, five showed evidence of colocalization (colocalization probability > 0.5): EXOSC9, CCNA2, HIST1H2BN, RP11-182L21.6, and RP11-327J17.2. Six of the 20 novel genes are not known to impact PCa risk. These findings yield new hypotheses for genetic factors underlying PSA levels that should be further explored toward improving our understanding of PSA biology.

Baseline Serum Prostate-specific Antigen Value Predicts the Risk of Subsequent Prostate Cancer Death-Results from the Norwegian Prostate Cancer Consortium.

BACKGROUND: Prostate-specific antigen (PSA) levels in midlife are strongly associated with the long-term risk of lethal prostate cancer in cohorts not subject to screening. This is the first study evaluating the association between PSA levels drawn as part of routine medical care in the Norwegian population and prostate cancer incidence and mortality. OBJECTIVE: To determine the association between midlife PSA levels <4.0 ng/ml, drawn as part of routine medical care, and long-term risk of prostate cancer death. DESIGN, SETTING, AND PARTICIPANTS: The Norwegian Prostate Cancer Consortium collected >8 million PSA results from >1 million Norwegian males ≥40 yr of age. We studied 176 099 men (predefined age strata: 40-54 and 55-69 yr) without a prior prostate cancer diagnosis who had a nonelevated baseline PSA level (<4.0 ng/ml) between January 1, 1995 and December 31, 2005. INTERVENTION: Baseline PSA. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We assessed the 16-yr risk of prostate cancer mortality. We calculated the discrimination (C-index) between predefined PSA strata (<0.5, 0.5-0.9, 1.0-1.9, 2.0-2.9, and 3.0-3.9 ng/ml) and subsequent prostate cancer death. Survival curves were plotted using the Kaplan-Meier method. RESULTS AND LIMITATIONS: The median follow-up time of men who did not get prostate cancer was 17.9 yr. Overall, 84% of men had a baseline PSA level of <2.0 ng/ml and 1346 men died from prostate cancer, with 712 deaths (53%) occurring in the 16% of men with the highest baseline PSA of 2.0-3.9 ng/ml. Baseline PSA levels were associated with prostate cancer mortality (C-index 0.72 for both age groups, 40-54 and 55-69 yr). The fact that the reason for any given PSA measurement remains unknown represents a limitation. CONCLUSIONS: We replicated prior studies that baseline PSA at age 40-69 yr can be used to stratify a man's risk of dying from prostate cancer within the next 15-20 yr. PATIENT SUMMARY: A prostate-specific antigen level obtained as part of routine medical care is strongly associated with a man's risk of dying from prostate cancer in the next two decades.

Predictive value of kallikrein forms and ß-microseminoprotein in blood from patients with evidence of detectable levels of PSA after radical prostatectomy.

PURPOSE: To determine whether ß-microseminoprotein or any of the kallikrein forms in blood-free, total or intact PSA or total hK2-predict metastasis in patients with evidence of detectable levels of PSA in blood after radical prostatectomy. METHOD: We determined marker concentrations in blood from 173 men treated with radical prostatectomy and evidence of detectable levels of PSA in the blood (PSA ≥ 0.05) after surgery between 2014 and 2015 and at least 1 year after any adjuvant therapy. We used Cox regression to determine whether any marker was associated with metastasis using both univariate and multivariable models that included standard clinical predictors. RESULTS: Overall, 42 patients had metastasis, with a median follow-up of 67 months among patients without an event. The levels of intact and free PSA and free-to-total PSA ratio were significantly associated with metastasis. Discrimination was highest for free PSA (c-index: 0.645) and free-to-total PSA ratio (0.625). Only free-to-total PSA ratio remained associated with overall metastasis (either regional or distant) after including standard clinical predictors (p = 0.025) and increased discrimination from 0.686 to 0.697. Similar results were found using distant metastasis as an outcome (p = 0.011; c-index increased from 0.658 to 0.723). CONCLUSION: Our results provide evidence that free-to-total PSA ratio can risk stratifying patients with evidence of detectable levels of PSA in blood after RP. Further research is warranted on the biology of prostate cancer markers in patients with evidence of detectable levels of PSA in blood after radical prostatectomy. Our findings on the free-to-total ratio for predicting adverse oncologic outcomes need to be validated in other cohorts.

Addition of a Genetic Risk Score for Identification of Men with a Low Prostate-specific Antigen Level in Midlife at Risk of Developing Lethal Prostate Cancer.

Men with a low prostate-specific antigen (PSA) level (<1 ng/ml) in midlife may extend the rescreening interval (if aged 40-59 yr) or forgo future PSA screening (if aged >60 yr) owing to their low risk of aggressive prostate cancer (PCa). However, there is a subset of men who develop lethal PCa despite low baseline PSA. We investigated how a PCa polygenic risk score (PRS) in addition to baseline PSA impacts the prediction of lethal PCa among 483 men aged 40-70 yr from the Physicians' Health Study followed over a median of 33 yr. We examined the association of the PRS with the risk of lethal PCa (lethal cases vs controls) using logistic regression adjusted for baseline PSA. The PCa PRS was associated with risk of lethal PCa (odds ratio per 1 standard deviation in PRS [OR] 1.79, 95% confidence interval [CI] 1.28-2.49). The association between the PRS and lethal PCa was stronger for those with PSA <1 ng/ml (OR 2.23, 95% CI 1.19-4.21) than for men with PSA ≥1 ng/ml (OR 1.61, 95% CI 1.07-2.42). Our PCa PRS improved the identification of men with PSA <1 ng/ml at greater risk of future lethal PCa who should consider ongoing PSA testing. Patient summary: A subset of men develop fatal prostate cancer despite having low prostate-specific antigen (PSA) levels in middle age. A risk score based on multiple genes can help in predicting men who may be at risk of developing lethal prostate cancer and who should be advised to have regular PSA measurements.

Quantitative In Vivo Imaging of the Androgen Receptor Axis Reveals Degree of Prostate Cancer Radiotherapy Response.

Noninvasive biomarkers for androgen receptor (AR) pathway activation are urgently needed to better monitor patient response to prostate cancer therapies. AR is a critical driver and mediator of resistance of prostate cancer but currently available noninvasive prostate cancer biomarkers to monitor AR activity are discordant with downstream AR pathway activity. External beam radiotherapy (EBRT) remains a common treatment for all stages of prostate cancer, and DNA damage induced by EBRT upregulates AR pathway activity to promote therapeutic resistance. [89Zr]11B6-PET is a novel modality targeting prostate-specific protein human kallikrein 2 (hK2), which is a surrogate biomarker for AR activity. Here, we studied whether [89Zr]11B6-PET can accurately assess EBRT-induced AR activity.Genetic and human prostate cancer mouse models received EBRT (2-50 Gy) and treatment response was monitored by [89Zr]11B6-PET/CT. Radiotracer uptake and expression of AR and AR target genes was quantified in resected tissue.EBRT increased AR pathway activity and [89Zr]11B6 uptake in LNCaP-AR and 22RV1 tumors. EBRT increased prostate-specific [89Zr]11B6 uptake in prostate cancer-bearing mice (Hi-Myc x Pb_KLK2) with no significant changes in uptake in healthy (Pb_KLK2) mice, and this correlated with hK2 protein levels. IMPLICATIONS: hK2 expression in prostate cancer tissue is a proxy of EBRT-induced AR activity that can noninvasively be detected using [89Zr]11B6-PET; further clinical evaluation of hK2-PET for monitoring response and development of resistance to EBRT in real time is warranted.

Young Age on Starting Prostate-specific Antigen Testing Is Associated with a Greater Reduction in Prostate Cancer Mortality: 24-Year Follow-up of the Göteborg Randomized Population-based Prostate Cancer Screening Trial.

BACKGROUND: The risk of death from prostate cancer (PC) depends on age, but the age at which to start prostate-specific antigen (PSA) screening remains uncertain. OBJECTIVE: To study the relationship between risk reduction for PC mortality and age at first PSA screening. DESIGN, SETTING, AND PARTICIPANTS: The randomized Göteborg-1 trial invited men for biennial PSA screening between the ages of 50 and 70 yr (screening, n = 10 000) or no invitation but exposure to opportunistic PSA testing (control, n = 10 000). INTERVENTION: Regular versus opportunistic PSA screening or no PSA. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We modeled the nonlinear association between starting age and the absolute risk reduction in PC mortality in three settings: (1) intention-to-screen (randomized arms); (2) historical control (screening group and 1990-1994 registry data); and (3) attendees only (screening attendees and matched controls). We tested whether the effect of screening on PC mortality depends on the age at starting screening by comparing survival models with and without an interaction between trial arm and age (intention-to-screen and attendees only). RESULTS AND LIMITATIONS: Younger age on starting PSA testing was associated with a greater reduction in PC mortality. Starting screening at age 55 yr approximately halved the risk of PC death compared to first PSA at age 60 yr. The test of association between starting age and the effect of screening on PC mortality was slightly greater than the conventional level of statistical significance (p = 0.052) for the entire cohort, and statistically significant among attendees (p = 0.002). This study is limited by the low number of disease-specific deaths for men starting screening before age 55 yr and the difficulty in discriminating between the effect of starting age and screening duration. CONCLUSIONS: Given that prior screening trials included men aged up to 70 yr on starting screening, our results suggest that the effect size reported in prior trials underestimates that of currently recommended programs starting at age 50-55 yr. PATIENT SUMMARY: In this study from the Göteborg-1 trial, we looked at the effect of prostate-specific antigen (PSA) screening in reducing men's risk of dying from prostate cancer given the age at which they begin testing. Starting at a younger age reduced the risk of prostate cancer death by a greater amount. We recommend that PSA screening should start no later than at age 55 yr.

Association of Prostate-Specific Antigen Levels with Prostate Cancer Risk in a Multiethnic Population: Stability Over Time and Comparison with Polygenic Risk Score.

BACKGROUND: Studies in men of European ancestry suggest prostate-specific antigen (PSA) as a marker of early prostate cancer development that may help to risk-stratify men earlier in life. METHODS: We examined PSA levels in men measured up to 10+ years before a prostate cancer diagnosis in association with prostate cancer risk in 2,245 cases and 2,203 controls of African American, Latino, Japanese, Native Hawaiian, and White men in the Multiethnic Cohort. We also compared the discriminative ability of PSA to polygenic risk score (PRS) for prostate cancer. RESULTS: Excluding cases diagnosed within 2 and 10 years of blood draw, men with PSA above the median had a prostate cancer OR (95% CIs) of 9.12 (7.66-10.92) and 3.52 (2.50-5.03), respectively, compared with men with PSA below the median. A PSA level above the median identified 90% and 75% of cases diagnosed more than 2 and 10 years after blood draw, respectively. The associations were significantly greater for Gleason ≤7 versus 8+ disease. At 10+ years, the association of prostate cancer with PSA was comparable with that with the PRS [OR per SD increase: 1.88 (1.45-2.46) and 2.12 (1.55-2.93), respectively]. CONCLUSIONS: We found PSA to be an informative marker of prostate cancer risk at least a decade before diagnosis across multiethnic populations. This association was diminished with increasing time, greater for low grade tumors, and comparable with a PRS when measured 10+ years before diagnosis. IMPACT: Our multiethnic investigation suggests broad clinical implications on the utility of PSA and PRS for risk stratification in prostate cancer screening practices.

Predicting Grade group 2 or higher cancer at prostate biopsy by 4Kscore in blood and uCaP microRNA model in urine.

Elevated prostate-specific antigen (PSA) levels often lead to unnecessary and possibly harmful transrectal ultrasound guided biopsy, e.g. when the biopsy is negative or contains only low-grade insignificant cancer, unlikely to become symptomatic in the man's normal lifespan. A model based on four-kallikrein markers in blood (commercialized as 4Kscore) predicts risk of Grade group 2 or higher prostate cancer at biopsy, reducing unnecessary biopsies. We assessed whether these results extend to a single institution prostate biopsy cohort of Danish men and are enhanced by three microRNAs from urine (referred to as uCaP). The 4Kscore measured in cryopreserved blood from 234 men referred for 10+ core biopsy to Aarhus University Hospital, 29 with PSA > 25 ng/ml. We explored uCaP in urine from 157 of these men. Combined with age and DRE findings, both 4Kscore and uCaP could accurately predict Grade group 2 or higher prostate cancer (all patients: AUC = 0.802 and 0.797; PSA ≤ 25: AUC = 0.763 and 0.759). There was no additive effect when combining the 4Kscore and uCaP. Limitations include a study cohort with higher risk than commonly reported for biopsy cohorts. Our findings further support the clinical use of the 4Kscore to predict Grade group 2 or higher cancers in men being considered for biopsy.

Results from 22 years of Followup in the Göteborg Randomized Population-Based Prostate Cancer Screening Trial.

PURPOSE: Our goal was to analyze results from 22 years of followup in the Göteborg randomized prostate cancer (PC) screening trial. MATERIALS AND METHODS: In December 1994, 20,000 men born 1930-1944 were randomly extracted from the Swedish population register and were randomized (1:1) into either a screening group (SG) or to a control group (CG). Men in the SG were repeatedly invited for biennial prostate specific antigen testing up to an average age of 69 years. Main endpoints were PC incidence and mortality (intention-to-screen principle). RESULTS: After 22 years, 1,528 men in the SG and 1,124 men in the CG had been diagnosed with PC. In total, 112 PC deaths occurred in the SG and 158 in the CG. Compared with the CG, the SG showed a PC incidence rate ratio (RR) of 1.42 (95% CI, 1.31-1.53) and a PC mortality RR of 0.71 (95% CI, 0.55-0.91). The 22-year cumulative PC mortality rate was 1.55% (95% CI, 1.29-1.86) in the SG and 2.13% (95% CI, 1.83-2.49) in the CG. Correction for nonattendance (Cuzick method) yielded a RR of PC mortality of 0.59 (95% CI, 0.43-0.80). Number needed to invite and number needed to diagnose was estimated to 221 and 9, respectively. PC death risk was increased in the following groups: nontesting men, men entering the program after age 60 and men with >10 years of followup after screening termination. CONCLUSIONS: Prostate specific antigen-based screening substantially decreases PC mortality. However, not attending, starting after age 60 and stopping at age 70 seem to be major pitfalls regarding PC death risk.

Prostate cancer polygenic risk score and prediction of lethal prostate cancer.

Polygenic risk scores (PRS) for prostate cancer incidence have been proposed to optimize prostate cancer screening. Prediction of lethal prostate cancer is key to any stratified screening program to avoid excessive overdiagnosis. Herein, PRS for incident prostate cancer was evaluated in two population-based cohorts of unscreened middle-aged men linked to cancer and death registries: the Västerbotten Intervention Project (VIP) and the Malmö Diet and Cancer study (MDC). SNP genotypes were measured by genome-wide SNP genotyping by array followed by imputation or genotyping of selected SNPs using mass spectrometry. The ability of PRS to predict lethal prostate cancer was compared to PSA and a commercialized pre-specified model based on four kallikrein markers. The PRS was associated with incident prostate cancer, replicating previously reported relative risks, and was also associated with prostate cancer death. However, unlike PSA, the PRS did not show stronger association with lethal disease: the hazard ratio for prostate cancer incidence vs. prostate cancer metastasis and death was 1.69 vs. 1.65 in VIP and 1.25 vs. 1.25 in MDC. PSA was a much stronger predictor of prostate cancer metastasis or death with an area-under-the-curve of 0.78 versus 0.63 for the PRS. Importantly, addition of PRS to PSA did not contribute additional risk stratification for lethal prostate cancer. We have shown that a PRS that predicts prostate cancer incidence does not have utility above and beyond that of PSA measured at baseline when applied to the clinically relevant endpoint of prostate cancer death. These findings have implications for public health policies for delivery of prostate cancer screening. Focusing polygenic risk scores on clinically significant endpoints such as prostate cancer metastasis or death would likely improve clinical utility.