Outcomes of 10 years of PSA screening for prostate cancer in Norwegian men with Lynch syndrome.

BACKGROUND: Pathogenic germline variants in the mismatch repair (MMR) genes are associated with an increased risk of prostate cancer (PCa). Since 2010 we have recommended MMR carriers annual PSA testing from the age of 40. Prospective studies of the outcome of long-term PSA screening are lacking. This study aimed to investigate the incidence and characteristics of PCa in Norwegian MMR carriers attending annual PSA screening (PSA threshold >3.0 ng/mL) to evaluate whether our recommendations should be continued. METHODS: This is a prospective observational study of 225 male MMR carriers who were recommended annual PSA screening by the Section of Inherited Cancer, Oslo University Hospital from 2010 and onwards. Incidence and tumor characteristics (age, PSA at diagnosis, Gleason score, TNM score) were described. IHC and MSI-analyses were done on available tumors. Standardized incidence ratio (SIR) was calculated based on data from the Cancer Registry of Norway. RESULTS: Twenty-two of 225 (9.8%) had been diagnosed with PCa, including 10/69 (14.5%) MSH2 carriers and 8/61 (13.1%) MSH6 carriers. Ten of 20 (50%) tumors had Gleason score ≥4 + 3 on biopsy and 6/11 (54.5%) had a pathological T3a/b stage. Eight of 17 (47.1%) tumors showed abnormal staining on IHC and 3/13 (23.1%) were MSI-high. SIR was 9.54 (95% CI 5.98-14.45) for all MMR genes, 13.0 (95% CI 6.23-23.9) for MSH2 and 13.74 for MSH6 (95% CI 5.93-27.08). CONCLUSIONS: Our results indicate that the MMR genes, and especially MSH2 and MSH6, are associated with a significant risk of PCa, and a high number of tumors show aggressive characteristics. While the impact of screening on patient outcomes remains to be more firmly established, the high SIR values we observe provide support for continued PSA screening of MSH2 and MSH6 carriers. Studies are needed to provide optimal recommendations for PSA-threshold and to evaluate whether MLH1 and PMS2 carriers should not be recommended screening.

Prostate cancer: Molecular aspects, consequences, and opportunities of the multifocal nature.

Prostate cancer is unique compared to other major cancers due to the presence of multiple primary malignant foci in the majority of patients at the time of diagnosis. Each malignant focus has distinct somatic mutations and gene expression patterns, which represents a challenge for the development of prognostic tests for localized prostate cancer. Additionally, the molecular heterogeneity of advanced prostate cancer has important implications for management, particularly for patients with metastatic and locally recurrent cancer. Studies have shown that prostate cancers with mutations in DNA damage response genes are more sensitive to drugs inhibiting the poly ADP-ribose polymerase (PARP) enzyme. However, testing for such mutations should consider both spatial and temporal heterogeneity. Here, we summarize studies where multiregional genomics and transcriptomics analyses have been performed for primary prostate cancer. We further discuss the vast interfocal heterogeneity and how prognostic biomarkers and a molecular definition of the index tumor should be developed. The concept of focal treatments in prostate cancer has been evolving as a demand from patients and clinicians and is one example where there is a need for defining an index tumor. Here, biomarkers must have proven value for individual malignant foci. The potential discovery and implementation of biomarkers that are agnostic to heterogeneity are also explored as an alternative to multisample testing. Thus, deciding upon whole-organ treatment, such as radical prostatectomy, should depend on information from biomarkers which are informative for the whole organ.

'High proliferative cribriform prostate cancer' defines a patient subgroup with an inferior prognosis.

AIMS: A cribriform pattern, reactive stroma (RS), PTEN, Ki67 and ERG are promising prognostic biomarkers in primary prostate cancer (PCa). We aim to determine the relative contribution of these factors and the Cancer of the Prostate Risk Assessment Postsurgical (CAPRA-S) score in predicting PCa prognosis. METHODS AND RESULTS: We included 475 patients who underwent radical prostatectomy (2010-12, median follow-up = 8.7 years). Cribriform pattern was identified in 57% of patients, PTEN loss in 55%, ERG expression in 51%, RS in 39% and high Ki67 in 9%. In patients with multiple samples from the same malignant focus and either PTEN loss or high Ki67, intrafocal heterogeneity for PTEN and Ki67 expression was detected in 55% and 89%, respectively. In patients with samples from two or more foci, interfocal heterogeneity was detected in 46% for PTEN and 6% for Ki67. A cribriform pattern and Ki67 were independent predictors of biochemical recurrence (BCR) and clinical recurrence (CR), whereas ERG expression was an independent predictor of CR. Besides CAPRA-S, a cribriform pattern provided the highest relative proportion of explained variation for predicting BCR (11%), and Ki67 provided the highest relative proportion of explained variation for CR (21%). In patients with a cribriform pattern, high Ki67 was associated with a higher risk of BCR [hazard ratio (HR) = 2.83, P < 0.001] and CR (HR = 4.35, P < 0.001). CONCLUSIONS: High Ki67 in patients with a cribriform pattern identifies a patient subgroup with particularly poor prognosis, which we termed 'high proliferative cribriform prostate cancer'. These results support reporting a cribriform pattern in pathology reports, and advocate implementing Ki67.

Somatic mutations reveal complex metastatic seeding from multifocal primary prostate cancer.

Primary prostate cancer shows a striking intraorgan molecular heterogeneity, with multiple spatially separated malignant foci in the majority of patients. Metastatic prostate cancer, however, typically reveals more homogenous molecular profiles, suggesting a monoclonal origin of the metastatic lesions. Longitudinal mutational spectra, comparing multiple primary lesions with metastases from the same patients remain poorly defined. We have here analyzed somatic mutations in multisampled, spatio-temporal biobanked lesions (38 samples from primary foci and 1 sample from each of 8 metastases from seven prostate cancer patients) applying a custom-designed panel targeting 68 prostate cancer relevant genes. The metastatic samples were taken at time of primary surgery and up to 7 years later, and sampling included circulating tumor DNA in plasma or solid metastatic tissue samples. A total of 282 somatic mutations were detected, with a range of 0 to 25 mutations per sample. Although seven samples had solely private mutations, the remaining 39 samples had both private and shared mutations. Seventy-four percent of mutations in metastases were not found in any primary samples, and vice versa, 96% of mutations in primary cancers were not found in any metastatic samples. However, for three patients, shared mutations were found suggesting the focus of origin, including mutations in AKT1, FOXA1, HOXB13, RB1 and TP53. In conclusion, the spatio-temporal heterogeneous nature of multifocal disease is emphasized in our study, and underlines the importance of testing a recent sample in genomics-based precision medicine for metastatic prostate cancer.

In situ expression of ERG protein in the context of tumor heterogeneity identifies prostate cancer patients with inferior prognosis.

Prognostic biomarkers for prostate cancer are needed to improve prediction of disease course and guide treatment decisions. However, biomarker development is complicated by the common multifocality and heterogeneity of the disease. We aimed to determine the prognostic value of candidate biomarkers transcriptional regulator ERG and related ETS family genes, while considering tumor heterogeneity. In a multisampled, prospective, and treatment-naïve radical prostatectomy cohort from one tertiary center (2010-2012, median follow-up 8.1 years), we analyzed ERG protein (480 patients; 2047 tissue cores), and RNA of several ETS genes in a subcohort (165 patients; 778 fresh-frozen tissue samples). Intra- and interfocal heterogeneity was identified in 29% and 33% (ERG protein) and 39% and 27% (ETS RNA) of patients, respectively. ERG protein and ETS RNA was identified exclusively in a nonindex tumor in 31% and 32% of patients, respectively. ERG protein demonstrated independent prognostic value in predicting biochemical (P = 0.04) and clinical recurrence (P = 0.004) and appeared to have greatest prognostic value for patients with Grade Groups 4-5. In conclusion, when heterogeneity is considered, ERG protein is a robust prognostic biomarker for prostate cancer.

Salmon Protein Hydrolysate Potentiates the Growth Inhibitory Effect of Bicalutamide on Human Prostate Cancer Cell Lines LNCaP and PC3 by Modulating Iron Homeostasis.

Prostate cancer is a common cause of cancer death in men. In advanced stages of prostate cancer, androgen deprivation therapy (ADT) is initiated. Despite ADT, prostate cancers invariably progress to become androgen independent. A growing body of evidence implicates iron dysmetabolism in prostate cancer progression. A bioactive peptide-rich salmon protein hydrolysate (SPH) has previously been demonstrated to modulate iron homeostatic mechanisms. In the present study, the anticancer effect of SPH and bicalutamide co-treatment on LNCaP and PC3 prostate cancer cell proliferation was investigated. Our results found that SPH potentiates the anti-proliferative effect of bicalutamide in a dose-dependent manner for both cell lines. In the presence of 160 µg/mL SPH, co-treatment with 1.0 µM bicalutamide decreased LNCaP cells' relative colony survival from 25% (1.0 µM bicalutamide monotreatment) to 2% after culturing for 12 days. For PC3 cells, the relative colony survival diminished from 52% (10.0 µM bicalutamide) to 32% at an SPH concentration of 160 µg/mL. Gene expression profiling, employing quantitative real-time PCR, revealed that the inhibitory effects were related to significant FTH1 up-regulation with a concomitant TFRC down-regulation. In conclusion, our results provide in vitro evidence that SPH potentiates the growth inhibitory effect of bicalutamide on prostate cancer cells by modulating iron homeostasis mechanisms.

Expressed prognostic biomarkers for primary prostate cancer independent of multifocality and transcriptome heterogeneity.

The majority of prostate cancer patients are diagnosed with multiple primary malignant foci. The distinct foci are exceptionally heterogeneous with regard to DNA mutations, but whether this is recapitulated at the transcriptome level remains unknown. In this study, inter- and intrafocal heterogeneity has been assessed by whole-transcriptome sequencing of 87 tissue samples from 23 patients with localized prostate cancer treated with radical prostatectomy. From each patient, multiple samples were taken from one or more malignant foci, in addition to one sample from benign prostate tissue. Transcriptomic profiles of different malignant foci from the same patient showed a similar level of heterogeneity as tumors from different patients. This applies to expression of genes, fusion genes, and somatic mutations. Within-patient pair-wise analyses identified expression patterns linked to ETS status and extraprostatic extension. A set of 62 genes were found with low intrapatient heterogeneity and high interpatient heterogeneity, retaining stable expression profiles across foci within the same patient. Among these, 16 genes are associated with biochemical recurrence in a separately published study and are therefore nominated as biomarkers with prognostic value regardless of which malignant focus is sampled. In conclusion, an extensive heterogeneity in multifocal prostate cancer is confirmed at the gene expression level. Diagnostic biomarkers were identified for ETS positive samples and samples from extraprostatic extensions. Finally, prognostic biomarkers independent of multifocal heterogeneity were found.

Collision tumors revealed by prospectively assessing subtype-defining molecular alterations in 904 individual prostate cancer foci.

BACKGROUNDProstate cancer is multifocal with distinct molecular subtypes. The utility of genomic subtyping has been challenged due to inter- and intrafocal heterogeneity. We sought to characterize the subtype-defining molecular alterations of primary prostate cancer across all tumor foci within radical prostatectomy (RP) specimens and determine the prevalence of collision tumors.METHODSFrom the Early Detection Research Network cohort, we identified 333 prospectively collected RPs from 2010 to 2014 and assessed ETS-related gene (ERG), serine peptidase inhibitor Kazal type 1 (SPINK1), phosphatase and tensin homolog (PTEN), and speckle type BTB/POZ protein (SPOP) molecular status. We utilized dual ERG/SPINK1 immunohistochemistry and fluorescence in situ hybridization to confirm ERG rearrangements and characterize PTEN deletion, as well as high-resolution melting curve analysis and Sanger sequencing to determine SPOP mutation status.RESULTSBased on index focus alone, ERG, SPINK1, PTEN, and SPOP alterations were identified in 47.5%, 10.8%, 14.3%, and 5.1% of RP specimens, respectively. In 233 multifocal RPs with ERG/SPINK1 status in all foci, 139 (59.7%) had discordant molecular alterations between foci. Collision tumors, as defined by discrepant ERG/SPINK1 status within a single focus, were identified in 29 (9.4%) RP specimens.CONCLUSIONInterfocal molecular heterogeneity was identified in about 60% of multifocal RP specimens, and collision tumors were present in about 10%. We present this phenomenon as a model for the intrafocal heterogeneity observed in previous studies and propose that future genomic studies screen for collision tumors to better characterize molecular heterogeneity.FUNDINGEarly Detection Research Network US National Cancer Institute (NCI) 5U01 CA111275-09, Center for Translational Pathology at Weill Cornell Medicine (WCM) Department of Pathology and Laboratory Medicine, US NCI (WCM SPORE in Prostate Cancer, P50CA211024-01), R37CA215040, Damon Runyon Cancer Research Foundation, US MetLife Foundation Family Clinical Investigator Award, Norwegian Cancer Society (grant 208197), and South-Eastern Norway Regional Health Authority (grant 2019016 and 2020063).

Long-term first-in-man Phase I/II study of an adjuvant dendritic cell vaccine in patients with high-risk prostate cancer after radical prostatectomy.

BACKGROUND: Patients with high-risk prostate cancer (PC) can experience biochemical relapse (BCR), despite surgery, and develop noncurative disease. The present study aimed to reduce the risk of BCR with a personalized dendritic cell (DC) vaccine, given as adjuvant therapy, after robot-assisted laparoscopic prostatectomy (RALP). METHODS: Twelve weeks after RALP, 20 patients with high-risk PC and undetectable PSA received DC vaccinations for 3 years or until BCR. The primary endpoint was the time to BCR. The immune response was assessed 7 weeks after surgery (baseline) and at one-time point during the vaccination period. RESULTS: Among 20 patients, 11 were BCR-free over a median of 96 months (range: 84-99). The median time from the end of vaccinations to the last follow-up was 57 months (range: 45-60). Nine patients developed BCR, either during (n = 4) or after (n = 5) the vaccination period. Among five patients diagnosed with intraductal carcinoma, three experienced early BCR during the vaccination period. All patients that developed BCR remained in stable disease within a median of 99 months (range: 74-99). The baseline immune response was significantly associated with the immune response during the vaccination period (p = 0.015). For patients diagnosed with extraprostatic extension (EPE), time to BCR was longer in vaccine responders than in non-responders (p = 0.09). Among 12 patients with the International Society of Urological Pathology (ISUP) grade 5 PC, five achieved remission after 84 months, and all mounted immune responses. CONCLUSION: Patients diagnosed with EPE and ISUP grade 5 PC were at particularly high risk of developing postsurgical BCR. In this subgroup, the vaccine response was related to a reduced BCR incidence. The vaccine was safe, without side effects. This adjuvant first-in-man Phase I/II DC vaccine study showed promising results. DC vaccines after curative surgery should be investigated further in a larger cohort of patients with high-risk PC.

Prediagnostic Serum 25-Hydroxyvitamin D and Mortality Among Bladder Cancer Patients in the Janus Serum Bank Cohort.

PURPOSE: Circulating 25-hydroxyvitamin D (25(OH)D) is inversely associated with overall cancer mortality and selected cancers, while for urothelial bladder cancer (BC) this relationship is unclear. We aimed to examine the association between 25(OH)D and BC mortality. MATERIALS AND METHODS: We used prediagnostic serum from 378 BC cases within the population-based Janus Cohort. Cox regression models estimated hazard ratios (HRs), with 95% confidence intervals (CIs), for the association between 25(OH)D and BC-specific and all-cause mortality. Restricted cubic splines were assessed to examine non-linear risk associations. Analyses were stratified by tumor invasiveness (non-muscle invasive BC (NMIBC) and muscle invasive BC (MIBC)). Additionally, the association between 25(OH)D and all-cause mortality was assessed for 378 cancer-free matched controls. RESULTS: 25(OH)D deficiency (<50 nmol/L) was associated with higher BC-specific mortality (HR 1.87, 95% CI 1.10-3.20), when compared with insufficient levels (50-74 nmol/L). Stratification by tumor invasiveness revealed that this result was evident for NMIBC only, both with respect to BC-specific mortality (HR 2.84, 95% CI 1.14-7.12) and all-cause mortality (HR 1.97, 95% CI 1.06-3.65). No association between 25(OH)D levels and all-cause mortality was found in cancer-free controls. CONCLUSION: 25(OH)D deficiency (<50 nmol/L) prior to a BC diagnosis was associated with increased risk of BC-specific mortality, when compared to insufficient levels (50-74 nmol/L). The results were evident among NMIBC patients only, suggesting a more critical role of vitamin D deficiency in an early stage of the disease.

Vitamin D and Vitamin D-binding protein and risk of bladder cancer: A nested case-control study in the Norwegian Janus Serum Bank Cohort.

BACKGROUND: High circulating levels of vitamin D (25(OH)D) are suggested to reduce the risk of urinary bladder cancer (BC), but the evidence is weak, and several studies lack sufficient adjustment for potential confounders (e.g., smoking, body mass index (BMI), and physical activity). Moreover, few studies have investigated the role of vitamin D-binding protein (DBP) in this context. We conducted a matched nested case-control study including 378 cases and 378 controls within the Norwegian population-based Janus cohort, using serum collected 5-41 years prior to diagnosis, to study 25(OH)D and BC risk, by taking circulating DBP into account. METHODS: Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), for 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, an estimate of unbound (free) 25(OH)D levels. We adjusted for smoking (status and pack-years), BMI, physical activity, education and (mutually) for 25(OH)D and DBP. Restricted cubic splines were employed to examine nonlinear associations. RESULTS: High optimal levels of circulating 25(OH)D (≥100 nmol/L) (HR 0.35, 95% CI 0.19-0.64) were associated with decreased BC risk, when compared with insufficient concentrations (50-74 nmol/L). This association was less pronounced for optimal levels (75-99 nmol/L) (HR = 0.69, 95% CI 0.47-1.01). Moreover, estimated free 25(OH)D, was associated with decreased BC risk for molar ratio 17-21 (HR 0.66, 95% CI 0.44-0.97) and ≥22 (HR 0.50, 95% CI 0.29-0.82), compared to molar ratio 11-16. The HR function for BC risk was not linear, rather reversed u-shaped, with the highest HR at 62.5 nmol/L and 13.5 molar ratio, respectively. CONCLUSION: High levels of total and estimated free 25(OH)D were associated with reduced risk of BC, compared with insufficient concentrations. DBP was not associated with BC risk. We did not observe any impact of DBP or any of the studied lifestyle factors on the association between 25(OH)D and BC.

High expression of SCHLAP1 in primary prostate cancer is an independent predictor of biochemical recurrence, despite substantial heterogeneity.

In primary prostate cancer, the common multifocality and heterogeneity are major obstacles in finding robust prognostic tissue biomarkers. The long noncoding RNA SCHLAP1 has been suggested, but its prognostic value has not been investigated in the context of tumor heterogeneity. In the present study, expression of SCHLAP1 was investigated using real-time RT-PCR in a multisampled series of 778 tissue samples from radical prostatectomies of 164 prostate cancer patients (median follow-up time 7.4 y). The prognostic value of SCHLAP1 was evaluated with biochemical recurrence as endpoint. In total, 29% of patients were classified as having high expression of SCHLAP1 in at least one malignant sample. Among these, inter- and intrafocal heterogeneity was detected in 72% and 56%, respectively. High expression of SCHLAP1 was shown to be a predictor of biochemical recurrence in both uni- and multivariable cox regression analyses (P < 0.001 and P = 0.02). High expression of SCHLAP1 was also significantly associated with adverse clinicopathological characteristics, including grade group, high pT stage, invasive cribriform growth/intraductal carcinoma of the prostate, and reactive stroma. In conclusion, high expression of SCHLAP1 in at least one malignant sample is a robust prognostic biomarker in primary prostate cancer. For the first time, high SCHLAP1 expression has been associated with the aggressive histopathologic feature reactive stroma. The expression of SCHLAP1 is highly heterogeneous, and analysis of multiple samples is therefore crucial in determination of the SCHLAP1 status of a patient.

The EPIC-26 domain scores after radical prostatectomy are associated with the personality trait of neuroticism.

PURPOSE: The personality trait of neuroticism represents vulnerability for mental distress to somatic health problems. There are few studies of neuroticism in prostate cancer patients. This study examines the levels of self-reported adverse effects (AEs) after robot-assisted radical prostatectomy (RALP) in Norwegian men with high or low levels of neuroticism. Neuroticism is also compared to relevant factors concerning their associations with various AEs. METHODS: Among 982 men who had RALP at Oslo University Hospital, Radiumhospitalet between 2005 and 2010, 79% responded to a mailed questionnaire in 2011. They rated AEs by completing the EPIC-26 questionnaire, and neuroticism on the Eysenck Personality Questionnaire (EPQ). Men with < 1 year's follow-up, treatment failure, and incomplete EPQ responses were omitted, leaving 524 men for analysis. The EPQ responses were dichotomized into low and high level of neuroticism. Stepwise multivariate linear regression analyses were used for examination of associations with the EPIC-26 domain scores. RESULTS: High neuroticism was reported by 20% (95% CI 17-23%) of the patients. On the EPIC-26 dimensions men with high neuroticism had significantly lower mean scores than men with low neuroticism. Most of these between-group differences were clinically significant. In multivariate regression analyses, high neuroticism contributed significantly to all EPIC-26 domains. CONCLUSION: Increased levels of AEs after RALP are significantly associated with high neuroticism. A short screening test should be added to the current EPIC-26 instrument to identify patients with high neuroticism. In these patients, pre-operative counseling should take into account their risk of increased AE experiences.

Lifestyle associated factors and risk of urinary bladder cancer: A prospective cohort study from Norway.

A number of lifestyle associated factors, such as high body mass index (BMI), low physical activity, and related metabolic disorders, are associated with increased risk of cancer at several sites. For urinary bladder cancer (BC), such studies show inconsistent results, which could result from inadequate adjustment for smoking and occupational exposure. In the population-based Janus Cohort (n = 292 851), we investigated the independent and combined impact of BMI, physical activity, blood pressure, and blood lipids on the risk of BC, by thorough adjustment for smoking and potential occupational exposure. We used cox proportional hazard regression to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for the associations between the lifestyle associated factors and BC risk. The associations observed were dependent on smoking status and gender. Among men, diastolic blood pressure (DBP) (HR 1.07, 95% CI 1.02-1.12) and systolic blood pressure (SBP) (HR 1.04, 95% CI 1.01-1.07) were positively associated with BC risk. Stratification by smoking status revealed a positive association between DBP and BC risk in never smokers (HR 1.14, 95% CI 1.00-1.30), while no association was seen for current and former smokers. A risk score, integrating information across the lifestyle factors was positively associated with BC risk in men (ptrend  = 0.043). In women, physical activity was associated with a decreased BC risk, but only among never smokers (HR 0.65, 95% CI 0.45-0.94). In conclusion, relations between lifestyle associated factors and BC risk were most evident in never smokers, suggesting that smoking dominates the relation in current smokers.

A cross-sectional study of current work ability after radical prostatectomy.

BACKGROUND: Work ability represents a person's subjective assessment of current ability to work compared to his lifetime best. Since many men with prostate cancer are retired, work ability represents a more relevant work measure than employment status. The primary aim was to examine the prevalence of men who had high versus moderate/poor current work ability compared to their lifetime best work ability at a mean of 3.0 years after robot-assisted laparoscopic prostatectomy. The secondary aim was to study variables associated with moderate/poor work ability at survey. METHODS: This is a questionnaire-based study of men who had robot-assisted laparoscopic prostatectomy at Oslo University Hospital, Radiumhospitalet between January 2005 and August 2010. Among them 777 responded (79%), 730 reported on current work ability, socio-demographic data, somatic and mental health, and typical adverse effects (the EPIC-26) after prostatectomy. High versus moderate/poor work ability was the primary outcome. Descriptive statistics and logistic regression analyses were applied. RESULTS: The mean age of the sample at survey was 65.5 years (SD 5.9). At survey 42% of the sample reported moderate/poor current work ability and 58% reported high work ability. In multivariable analysis older age at survey, low basic education, comorbidity, poor self-rated health, presence of depression and low EPIC-26 hormonal domain score remained significantly associated with moderate/poor work ability. CONCLUSIONS: Current work ability is a useful measure for the working capacity particularly of retired men. Socio-demographic, cancer-related, health, psychological and typical adverse effect variables were significantly associated with moderate/poor current work ability after robot-assisted laparoscopic prostatectomy, and several health and psychological variables are amenable to identification and treatment by health care providers.

Interfocal heterogeneity challenges the clinical usefulness of molecular classification of primary prostate cancer.

Prostate cancer is a highly heterogeneous disease and typically multiple distinct cancer foci are present at primary diagnosis. Molecular classification of prostate cancer can potentially aid the precision of diagnosis and treatment. A promising genomic classifier was published by The Cancer Genome Atlas (TCGA), successfully classifying 74% of primary prostate cancers into seven groups based on one cancer sample per patient. Here, we explore the clinical usefulness of this classification by testing the classifier's performance in a multifocal context. We analyzed 106 cancer samples from 85 distinct cancer foci within 39 patients. By somatic mutation data from whole-exome sequencing and targeted qualitative and quantitative gene expression assays, 31% of the patients were uniquely classified into one of the seven TCGA classes. Further, different samples from the same focus had conflicting classification in 12% of the foci. In conclusion, the level of both intra- and interfocal heterogeneity is extensive and must be taken into consideration in the development of clinically useful molecular classification of primary prostate cancer.