Tumor characteristics of carriers and noncarriers of the deCODE 8q24 prostate cancer susceptibility alleles

Genetic Factors Associated with Prostate Cancer Conversion from Active Surveillance to Treatment

Men diagnosed with low-risk prostate cancer (PC) are increasingly electing active surveillance (AS) as their initial management strategy. While this may reduce the side effects of treatment for prostate cancer, many men on AS eventually convert to active treatment. PC is one of the most heritable cancers, and genetic factors that predispose to aggressive tumors may help distinguish men who are more likely to discontinue AS. To investigate this, we undertook a multi-institutional genome-wide association study (GWAS) of 5,222 PC patients and 1,139 other patients from replication cohorts, all of whom initially elected AS and were followed over time for the potential outcome of conversion from AS to active treatment. In the GWAS we detected 18 variants associated with conversion, 15 of which were not previously associated with PC risk. With a transcriptome-wide association study (TWAS), we found two genes associated with conversion (MAST3, p = 6.9×10-7 and GAB2, p = 2.0×10-6). Moreover, increasing values of a previously validated 269-variant genetic risk score (GRS) for PC was positively associated with conversion (e.g., comparing the highest to the two middle deciles gave a hazard ratio [HR] = 1.13; 95% Confidence Interval [CI]= 0.94-1.36); whereas, decreasing values of a 36-variant GRS for prostate-specific antigen (PSA) levels were positively associated with conversion (e.g., comparing the lowest to the two middle deciles gave a HR = 1.25; 95% CI, 1.04-1.50). These results suggest that germline genetics may help inform and individualize the decision of AS-or the intensity of monitoring on AS-versus treatment for the initial management of patients with low-risk PC.

Prostate cancer health disparities: An immuno-biological perspective

Prostate cancer (PCa) is the most commonly diagnosed malignancy in males, and, in the United States, is the second leading cause of cancer-related death for men older than 40 years. There is a higher incidence of PCa for African Americans (AAs) than for European-Americans (EAs). Investigations related to the incidence of PCa-related health disparities for AAs suggest that there are differences in the genetic makeup of these populations. Other differences are environmentally induced (e.g., diet and lifestyle), and the exposures are different. Men who immigrate from Eastern to Western countries have a higher risk of PCa than men in their native countries. However, the number of immigrants developing PCa is still lower than that of men in Western countries, suggesting that genetic factors are involved in the development of PCa. Altered genetic polymorphisms are associated with PCa progression. Androgens and the androgen receptor (AR) are involved in the development and progression of PCa. For populations with diverse racial/ethnic backgrounds, differences in lifestyle, diet, and biology, including genetic mutations/polymorphisms and levels of androgens and AR, are risk factors for PCa. Here, we provide an immuno-biological perspective on PCa in relation to racial/ethnic disparities and identify factors associated with the disproportionate incidence of PCa and its clinical outcomes.

The genetic epidemiology of prostate cancer and its clinical implications

Worldwide, familial and epidemiological studies have generated considerable evidence of an inherited component to prostate cancer. Indeed, rare highly penetrant genetic mutations have been implicated. Genome-wide association studies (GWAS) have also identified 76 susceptibility loci associated with prostate cancer risk, which occur commonly but are of low penetrance. However, these mutations interact multiplicatively, which can result in substantially increased risk. Currently, approximately 30% of the familial risk is due to such variants. Evaluating the functional aspects of these variants would contribute to our understanding of prostate cancer aetiology and would enable population risk stratification for screening. Furthermore, understanding the genetic risks of prostate cancer might inform predictions of treatment responses and toxicities, with the goal of personalized therapy. However, risk modelling and clinical translational research are needed before we can translate risk profiles generated from these variants into use in the clinical setting for targeted screening and treatment.

Nuclear envelope invaginations and cancer

The nuclear envelope (NE) surrounds the nucleus and separates it from the cytoplasm. The NE is not a passive structural component, but rather contributes to various cellular processes such as genome organization, transcription, signaling, and stress responses. Although the NE is mostly a smooth surface, it also forms invaginations that can reach deep into the nucleoplasm and may even traverse the nucleus completely. Cancer cells are generally characterized by irregularities and invaginations of the NE that are of diagnostic and prognostic significance. In the current chapter, we describe the link between nuclear invaginations and irregularities with cancer and explore possible mechanistic roles they might have in tumorigenesis.

Minireview: the molecular and genomic basis for prostate cancer health disparities

Despite more aggressive screening across all demographics and gradual declines in mortality related to prostate cancer (PCa) in the United States, race disparities persist. For African American men (AAM), PCa is more often an aggressive disease showing increased metastases and greater PCa-related mortality compared with European American men. The earliest research points to how distinctions are likely the result of a combination of factors, including ancestry genetics and lifestyle variables. More recent research considers that cancer, although influenced by external forces, is ultimately a disease primarily driven by aberrations observed in the molecular genetics of the tumor. Research studying PCa predominantly from European American men shows that indolent and advanced or metastatic prostate tumors have distinguishing molecular genomic make-ups. Early yet increasing evidence suggests that clinically distinct PCa from AAM also display molecular distinctions. It is reasonable to predict that further study will reveal molecular subtypes and various frequencies for PCa subtypes among diverse patient groups, thereby providing insight as to the genomic lesions and gene signatures that are functionally implicated in carcinogenesis or aggressive PCa in AAM. That knowledge will prove useful in developing strategies to predict who will develop advanced PCa among AAM and will provide the rationale to develop effective individualized treatment strategies to overcome disparities.

Emerging putative biomarkers: the role of alpha 2 and 6 integrins in susceptibility, treatment, and prognosis

The genetic architecture underpinning prostate cancer is complex, polygenic and despite recent significant advances many questions remain. Advances in genetic technologies have greatly improved our ability to identify genetic variants associated with complex disease including prostate cancer. Genome-wide association studies (GWASs) and microarray gene expression studies have identified genetic associations with prostate cancer susceptibility and tumour development. The integrins feature prominently in both studies examining the underlying genetic susceptibility and mechanisms driving prostate tumour development. Integrins are cell adhesion molecules involved in extracellular and intracellular signalling and are imperative for tumour development, migration, and angiogenesis. Although several integrins have been implicated in tumour development, the roles of integrin α(2) and integrin α(6) are the focus of this paper as evidence is now emerging that these integrins are implicit in prostate cancer susceptibility, cancer stem cell biology, angiogenesis, cell migration, and metastases to bone and represent potential biomarkers and therapeutic targets. There currently exists an urgent need to develop tools that differentiate indolent from aggressive prostate cancers and predict how patients will respond to treatment. This paper outlines the evidence supporting the use of α(2) and α(6) integrins in clinical applications for tailored patient treatment.

8q24 and 17q prostate cancer susceptibility loci in a multiethnic Asian cohort

OBJECTIVES

Recently, several genome-wide association studies have demonstrated a cumulative association of 5 polymorphic variants in chromosomes 8q24 and 17q with prostate cancer (CaP) risk in Caucasians, particularly those harboring aggressive clinicopathologic characteristics. The purpose of this study was to evaluate the influence of these variants on CaP susceptibility in Singaporean Asian men.

MATERIALS AND METHODS

We performed a case-control study in 289 Chinese CaP patients and 412 healthy subjects (144 Chinese, 134 Malays, and 134 Indians), and examined the association of the 5 single nucleotide polymorphisms (SNPs) with CaP.

RESULTS

In the healthy subjects, rs16901979 A-allele frequency was highest amongst Chinese (0.32) compared with Malays (0.13; P < 0.0001) or Indians (0.09; P < 0.0001); rs6983267 G-allele was highest in Indians (0.51) compared with Chinese (0.42; P = 0.041) or Malays (0.43; P = 0.077); whereas rs1859962 G-allele frequency was highest amongst Indians (0.56) compared with Chinese (0.40; P = 0.0002) or Malays (0.38; P < 0.0001). Individuals with the rs4430796 TT genotype were at increased CaP risk in the Chinese via a recessive model (odds ratios (OR) = 1.56, 95% CI = 1.04-2.33). Significant associations were observed for rs4430796 TT with Gleason scores of ≥ 7 (OR = 1.76, 95% CI = 1.14-2.73) and prostate-specific antigen (PSA) levels of ≥ 10 ng/ml at diagnosis (OR = 1.63, 95% CI = 1.01-2.63), as well as for rs6983267 GG with stage 3-4 CaPs (OR = 1.91, 95% CI = 1.01-3.61). A cumulative gene interaction influence on disease risk, which approximately doubled for individuals with at least 2 susceptibility genotypes, was also identified (OR = 2.18, 95% CI = 1.10-4.32).

CONCLUSIONS

This exploratory analysis suggests that the 5 genetic variants previously described may contribute to prostate cancer risk in Singaporean men.

Genetic variants associated with predisposition to prostate cancer and potential clinical implications

Prostate cancer is the commonest cancer in the developed world. There is an inherited component to this disease as shown in familial and twin studies. However, the discovery of these variants has been difficult. The emergence of genome-wide association studies has led to the identification of over 46 susceptibility loci. Their clinical utility to predict risk, response to treatment, or treatment toxicity, remains undefined. Large consortia are needed to achieve adequate statistical power to answer these genetic-clinical and genetic-epidemiological questions. International collaborations are currently underway to link genetic with clinical/epidemiological data to develop risk prediction models, which could direct screening and treatment programs.

Does absolute neutrophil count predict high tumor grade in African-American men with prostate cancer?

BACKGROUND

African-Americans (AA) are at risk for benign ethnic neutropenia (BEN), which has been implicated as a potential source of disparity in cancer outcomes among AAs. Since AAs with prostate cancer (PCa) are more likely to have aggressive pathological features, this investigation sought to determine if absolute neutrophil count (ANC) is associated with adverse pathologic findings at radical prostatectomy (RP) within a cohort of AA men.

METHODS

A single-institution, retrospective review was conducted of all AA patients undergoing RP who had a pre-operative CBC with differential and known RP pathology. Neutropenia was defined as ANC ≤1.5 × 10(9) /L (1.5). Clinical and pathologic variables were characterized for the study cohort, and Cox regression and Kaplan-Meier analyses performed to evaluate the association between ANC and adverse pathology.

RESULTS

A total of 336 patients were included, and 18 patients (5.4%) had ANC ≤1.5. Mean age was 59.8 ± 7.5 years; mean follow-up time 47.4 ± 43.3 months. Neutropenic patients had significantly higher clinical stages and pathologic Gleason scores (P < 0.05). On multivariable analysis, ANC ≤1.5 was significantly predictive of high tumor grade (HR 1.22, CI 1.01-1.48).

CONCLUSIONS

Neutropenia in AAs predicts high tumor grade at prostatectomy. Further studies are necessary to further characterize the importance of these findings with regard to the pathogenesis of PCa, particularly as it relates to the AA population.

Chromosomal regions associated with prostate cancer risk localize to lamin B-deficient microdomains and exhibit reduced gene transcription

The lamins are major determinants of nuclear shape and chromatin organization and these features are frequently altered in prostate cancer (CaP). Human CaP cell lines frequently have nuclear lobulations, which are enriched in A-type lamins but lack B-type lamins and have been defined as lamin B-deficient microdomains (LDMDs). LDMD frequency is correlated with CaP cell line aggressiveness and increased cell motility. In addition, LNCaP cells grown in the presence of dihydrotestosterone (DHT) show an increased frequency of LDMDs. The LDMDs are enriched in activated RNA polymerase II (Pol IIo) and androgen receptor (AR) and A-type lamins form an enlarged meshwork that appears to co-align with chromatin fibres and AR. Furthermore, fluorescence in situ hybridization and comparative genomic hybridization demonstrated that chromosomal regions associated with CaP susceptibility are preferentially localized to LDMDs. Surprisingly, these regions lack histone marks for transcript elongation and exhibit reduced BrU incorporation, suggesting that Pol II is stalled within LDMDs. Real-time PCR of genes near androgen response elements (AREs) was used to compare transcription between cells containing LDMDs and controls. Genes preferentially localized to LDMDs showed significantly decreased expression, while genes in the main nuclear body were largely unaffected. Furthermore, LDMDs were observed in human CaP tissue and the frequency was correlated with increased Gleason grade. These results imply that lamins are involved in chromatin organization and Pol II transcription, and provide insights into the development and progression of CaP.

Association of prostate cancer risk alleles with unfavourable pathological characteristics in potential candidates for active surveillance

OBJECTIVE

• To assess whether the carrier status of 35 risk alleles for prostate cancer (CaP) is associated with having unfavourable pathological features in the radical prostatectomy specimen in men with clinically low risk CaP who fulfil commonly accepted criteria as candidates for active surveillance.

PATIENTS AND METHODS

• We studied men of European ancestry with CaP who fulfilled the commonly accepted clinical criteria for active surveillance (T1c, prostate-specific antigen <10 ng/mL, biopsy Gleason ≤6, three or fewer positive cores, ≤50% tumour involvement/core) but instead underwent early radical prostatectomy. • We genotyped these men for 35 CaP risk alleles. We defined 'unfavourable' pathological characteristics to be Gleason ≥7 and/or ≥ pT2b in their radical prostatectomy specimen.

RESULTS

• In all, 263 men (median age 60 [46-72] years) fulfilled our selection criteria for active surveillance, and 58 of 263 (22.1%) were found to have 'unfavourable' pathological characteristics. • The frequencies of three CaP risk alleles (rs1447295 [8q24], P= 0.004; rs1571801 [9q33.2], P= 0.03; rs11228565 [11q13], P= 0.02) were significantly higher in men with 'unfavourable' pathological characteristics. • Two other risk alleles were proportionately more frequent (rs10934853 [3q21], P= 0.06; rs1859962 [17q24], P= 0.07) but did not achieve nominal statistical significance. • Carriers of any one of the significantly over-represented risk alleles had twice the likelihood of unfavourable tumour features (P= 0.03), and carriers of any two had a sevenfold increased likelihood (P= 0.001). • Receiver-operator curve analysis demonstrated an area under the curve of 0.66, suggesting that the number of single nucleotide polymorphisms carried provided discrimination between men with 'favourable' and 'unfavourable' tumour features in their prostatectomy specimen.

CONCLUSION

• In potential candidates for active surveillance, certain CaP risk alleles are more prevalent in patients with 'unfavourable' pathological characteristics in their radical prostatectomy specimen.

Early detection of prostate cancer with emphasis on genetic markers

BACKGROUND

The recent advances in genomic research have made it possible to identify several new genomic-based biomarkers for prostate cancer. In this review we evaluate these new markers and speculate about future scenarios.

RESULTS

Today 35 single nucleotide polymorphisms (SNPs) have been identified and independently validated to associate with prostate cancer. These SNPs are common in the population (>5%) but the effect of these SNPs in these regions on prostate cancer risk is modest with odds ratios typically ranging between 1.1 and 1.3. It is estimated that these markers explain 25% of the familial risk of prostate cancer. However, it is anticipated that additional 50-75 prostate cancer SNPs will be identified in the near future. The SNPs associated with prostate cancer so far are not associated with disease stage or outcome. There are several efforts to identify germline genetic markers that can be used as prognostic markers. There are also tumor-based methods that are promising in identifying new genetic markers that can be easily measured in plasma or urine.

CONCLUSION

There are several new "genetic" markers that in the near future might be used in clinical routine. These markers are easy to measure and stable over time. However the challenge is not only to identify new biomarkers but the real test is to validate new biomarkers in several large well-characterized patient populations. This validation must be done together will all other known biomarkers at the same time as it not likely that one single marker is enough, but a panel of different markers. Today 2010 there are over 19 000 publications in the area of biomarkers and prostate cancer, but only one biomarker, PSA, is used in the clinic today!

Prostate cancer risk alleles significantly improve disease detection and are associated with aggressive features in patients with a "normal" prostate specific antigen and digital rectal examination

BACKGROUND

Several reports suggest that a combination of risk alleles may be associated with prostate cancer (CaP) risk and tumor features. However, their ability to detect CaP and tumor characteristics in patients with a "normal" PSA (<4 ng/ml) and non-suspicious digital rectal examination (DRE) remains to be determined.

METHODS

We examined 203 men of European ancestry with clinical stage T1c CaP diagnosed at a "normal" PSA and 611 healthy volunteer controls. The genotypes for 17 different risk alleles were compared between CaP cases and controls. Additional analyses were used to compare the pathologic features between carriers and non-carriers (defined using best-fit genetic model) of these variants.

RESULTS

All risk alleles were present at an increased frequency in cases with "normal" PSA values and DRE compared to controls. Amongst CaP patients, carriers of an increasing number of genetic risk factors (i.e., alleles and positive family history) were at a significantly increased risk of CaP (P-trend <0.001). Specifically, men with >10 genetic risk factors had an 11.2-fold risk (95% CI 4.3-29.2) of having the disease compared to men with ≤5 variants. There also was a higher frequency of many the variants amongst men with adverse pathologic features.

CONCLUSIONS

A substantial proportion of biopsy-detectable CaP occurs in men with "normal" PSA levels and negative DRE. In this population, CaP risk alleles and family history are significantly associated with CaP risk and may help predict aggressive disease. Future studies are warranted to determine the utility of incorporating these variants into CaP screening programs.

Number of prostate cancer risk alleles may identify possibly 'insignificant' disease

OBJECTIVE

To determine whether the cumulative effects of five prostate cancer risk alleles (three single-nucleotide polymorphisms [SNPs] on chromosome 8Q24 and two SNPs on chromosome 17a) could help to identify possibly 'insignificant' disease.

MATERIALS AND METHODS

We genotyped 629 men of European ancestry who underwent radical prostatectomy at our institution between 2002 and 2007. Possibly 'insignificant' CaP was defined using the Ohori criteria (organ-confined, tumour volume <0.5 mL, Gleason pattern ≤4). Statistical analysis was used to compare patients with 'insignificant' and all other 'significant' cancer based upon genotype. Carrier status for the 5 SNPs were compared between patients with 'insignificant' disease and a separate population of 801 controls without CaP.

RESULTS

Overall, 38 (6.0%) patients with CaP met the Ohori criteria for 'insignificant' disease. Men with 'significant' cancer had a greater frequency of any of the five risk alleles than either patients with 'insignificant' disease or controls. None of the individual alleles genotyped on chromosomes 8 or 17 distinguished between 'significant' and 'insignificant' CaP. However, carriers of two or more risk alleles were more likely to have 'significant' disease.

CONCLUSIONS

Although no single risk allele distinguished 'insignificant' CaP, 'insignificant' disease was nearly three times as likely among carriers of ≤ one risk allele. Future studies are needed to further elucidate the cumulative relationship between CaP risk alleles and CaP aggressiveness.

Prostate cancer genomics: can we distinguish between indolent and fatal disease using genetic markers?

Prostate cancer is one of the most heritable cancers in men, and recent genome-wide association studies have revealed numerous genetic variants associated with disease. The risk variants identified using case-control designs that compared unaffected individuals with all types of patients with prostate cancer show little or no ability to discriminate between indolent and fatal forms of this disease. This suggests different genetic components are involved in the initiation as compared with the prognosis of prostate cancer. Future studies contrasting patients with more and less aggressive disease, and exploring association with disease progression and prognosis, should be more effective in detecting genetic risk factors for prostate cancer outcome.

Genetic prostate cancer risk assessment: common variants in 9 genomic regions are associated with cumulative risk

PURPOSE

Five genetic variants along chromosomes 8q24 and 17q have a cumulative association with prostate cancer risk. Our research group previously reported an association between these variants and clinicopathological characteristics. More recently 4 additional prostate cancer susceptibility variants were identified on chromosomes 2p15, 10q11, 11q13 and Xp11. We performed cumulative risk assessment incorporating all 9 genetic variants and determined the relationship of the new variants to clinicopathological tumor features.

MATERIALS AND METHODS

The genotype of 9 variants was determined in 687 men of European ancestry who underwent radical prostatectomy from 2002 to 2008 and in 777 healthy volunteer controls. We compared the incidence of these variants in prostate cancer cases and controls, and assessed their cumulative risk. We also determined the relationship of carrier status for the 4 new variants and clinicopathological tumor features.

RESULTS

Prostate cancer cases had an increased incidence of all 9 risk variants compared to controls. A cumulative model including the 9 single nucleotide polymorphisms provided greater prostate cancer risk stratification than a model restricted to the original 5 single nucleotide polymorphisms described. Specifically men with 6 or more variants were at greater than 6-fold increased risk for prostate cancer. Although 2p15 and 11q13 carriers were more likely to have aggressive features, other clinicopathological features were similar in carriers and noncarriers.

CONCLUSIONS

Genetic variants located in 9 regions have a cumulative association with prostate cancer risk. Identification of an increasing number of single nucleotide polymorphisms may provide greater understanding of their combined relationship with CaP risk and disease aggressiveness.

Common variants at 8q24 are associated with prostate cancer risk in Taiwanese men

BACKGROUND

Recently, independent genome-wide scans have found multiple genetic variants at 8q24 to be associated with prostate cancer risk. This study was performed to determine whether two of the variants more strongly associated with prostate cancer risk in European and American populations, specifically rs16901979 and rs6983561, were also associated with prostate cancer risk in Taiwanese men.

METHODS

We conducted a case-control study comprising of 340 prostate patients and 336 healthy controls. Genotyping was performed for rs16901979 and rs6983561. Their association with disease stage, tumor grade, PSA level and disease aggressiveness was also determined.

RESULTS

The risk allele A of rs16901979 was associated with a 1.28-fold increase in prostate cancer risk (P = 0.046), and the risk allele C of rs6983561 was associated with a 1.40-fold increase in prostate cancer risk (P = 0.006). When compared with controls, the risk allele of rs6983561 was more frequent in patients with more aggressive disease. Analysis of the cumulative risk of rs1447295, a confirmed risk variant, and one of these markers showed that compared to men who do not have any of these risk variants, men who carry any combination of 1 or 2 risk genotypes have a gradually increased prostate cancer risk (P for trend <0.001).

CONCLUSION

The variants rs16901979 and rs6983561 at 8q24 are associated with prostate cancer risk in Taiwanese men.

Evidence supports a faster growth rate and/or earlier transformation to clinically significant prostate cancer in black than in white American men, and influences racial progression and mortality disparity

PURPOSE

The incidence of prostate cancer is approximately 60% higher and the mortality rate is 2 to 3 times greater in black than in white American men. We propose that a more rapid prostate cancer growth rate and/or earlier transformation from latent to aggressive prostate cancer in black than in white men contribute to this disparity.

MATERIALS AND METHODS

We evaluated entirely embedded prostate glands on autopsy from 1,056 black and white men who died of causes other than prostate cancer. We also reviewed data from our radical prostatectomy database and from the Detroit Surveillance, Epidemiology and End Results database.

RESULTS

Autopsy data indicated that subclinical prostate cancer in black and white men starts at early age and clinical characteristics do not differ by race at early ages. Radical prostatectomy specimen data revealed that prostate cancer volume and Gleason grade were greater in black than in white men. Advanced or metastatic prostate cancer occurred at a 4:1 ratio in black and white men, respectively, in the Detroit Surveillance, Epidemiology and End Results registry database.

CONCLUSIONS

Results showed that age at prostate cancer initiation and clinical characteristics did not differ by race in our autopsy series, prostate cancer volume after radical prostatectomy was greater in black than in white men and disease became distant disease at a ratio of 4 black men to 1 white man in the Detroit Surveillance, Epidemiology and End Results population. These findings support the concept that prostate cancer grows more rapidly in black than in white men and/or earlier transformation from latent to aggressive prostate cancer occurs in black than in white men.

Prostate cancer risk allele specific for African descent associates with pathologic stage at prostatectomy

PURPOSE

A region on chromosome 8q24 was recently identified as a novel prostate cancer risk locus. Inherited variation in this region is associated with prostate cancer risk in the general population (21-58%), and specific alleles show a strong association in African-American men. This study was designed to evaluate associations between 8q24 risk alleles and clinical variables, such as pathologic stage, age at diagnosis, and recurrence, in a case series of African-American men.

EXPERIMENTAL DESIGN

Peripheral blood DNA samples from 114 African-American men with prostate cancer, including 106 who had undergone radical prostatectomy, were genotyped for six single-nucleotide polymorphisms on three 8q24 regions. The presence of these single-nucleotide polymorphisms was compared with clinicopathologic and follow-up data after radical prostatectomy.

RESULTS

The mean age of diagnosis and follow-up time were 57.4 (+/-8.9) years and 49.1 (+/-31.6) months, respectively. Patients carrying the Broad11934905 A risk allele, which is specific for African ancestry, were more likely to have a higher pathologic stage (pT(3-4)) than individuals with the wild type (odds ratio, 4.48; 95% confidence interval, 1.42-14.14; P = 0.011). A trend toward increased frequency of and shorter time to biochemical recurrence was noted in patients with this risk allele on Kaplan-Meier unadjusted survival analysis (P = 0.076).

CONCLUSIONS

The Broad11934905 polymorphism at 8q24, which is only found in people of African ancestry, is associated with an increase in non-organ-confined prostate cancer at prostatectomy. In addition, for those with this risk allele, there is a trend toward early biochemical recurrence that requires validation in larger studies.

Inherited genetic variant predisposes to aggressive but not indolent prostate cancer

Autopsy studies suggest that most aging men will develop lesions that, if detected clinically, would be diagnosed as prostate cancer (PCa). Most of these cancers are indolent and remain localized; however, a subset of PCa is aggressive and accounts for more than 27,000 deaths in the United States annually. Identification of factors specifically associated with risk for more aggressive PCa is urgently needed to reduce overdiagnosis and overtreatment of this common disease. To search for such factors, we compared the frequencies of SNPs among PCa patients who were defined as having either more aggressive or less aggressive disease in four populations examined in the Genetic Markers of Susceptibility (CGEMS) study performed by the National Cancer Institute. SNPs showing possible associations with disease severity were further evaluated in an additional three independent study populations from the United States and Sweden. In total, we studied 4,829 and 12,205 patients with more and less aggressive disease, respectively. We found that the frequency of the TT genotype of SNP rs4054823 at 17p12 was consistently higher among patients with more aggressive compared with less aggressive disease in each of the seven populations studied, with an overall P value of 2.1 x 10(-8) under a recessive model, exceeding the conservative genome-wide significance level. The difference in frequency was largest between patients with high-grade, non-organ-confined disease compared with those with low-grade, organ-confined disease. This study demonstrates that inherited variants predisposing to aggressive but not indolent PCa exist in the genome, and suggests that the clinical potential of such variants as potential early markers for risk of aggressive PCa should be evaluated.

Individual and cumulative effect of prostate cancer risk-associated variants on clinicopathologic variables in 5,895 prostate cancer patients

BACKGROUND

More than a dozen single nucleotide polymorphisms (SNPs) have been associated with prostate cancer (PCa) risk from genome-wide association studies (GWAS). Their association with PCa aggressiveness and clinicopathologic variables is inconclusive.

METHODS

Twenty PCa risk SNPs implicated in GWAS and fine mapping studies were evaluated in 5,895 PCa cases treated by radical prostatectomy at Johns Hopkins Hospital, where each tumor was uniformly graded and staged using the same protocol.

RESULTS

For 18 of the 20 SNPs examined, no statistically significant differences (P > 0.05) were observed in risk allele frequencies between patients with more aggressive (Gleason scores > or =4 + 3, or stage > or =T3b, or N+) or less aggressive disease (Gleason scores < or =3 + 4, and stage < or =T2, and N0). For the two SNPs that had significant differences between more and less aggressive disease rs2735839 in KLK3 (P = 8.4 x 10(-7)) and rs10993994 in MSMB (P = 0.046), the alleles that are associated with increased risk for PCa were more frequent in patients with less aggressive disease. Since these SNPs are known to be associated with PSA levels in men without PCa diagnoses, these latter associations may reflect the enrichment of low grade, low stage cases diagnosed by contemporary disease screening with PSA.

CONCLUSIONS

The vast majority of PCa risk-associated SNPs are not associated with aggressiveness and clinicopathologic variables of PCa. Correspondingly, they have minimal utility in predicting the risk for developing more or less aggressive forms of PCa.

Early prostate-specific antigen changes and the diagnosis and prognosis of prostate cancer

PURPOSE OF REVIEW

To delineate how recent findings on prostate-specific antigen (PSA) can improve prediction of risk, detection, and prediction of clinical endpoints of prostate cancer (PCa).

RECENT FINDINGS

The widely used PSA cut-point of 4.0 ng/ml increasingly appears arbitrary, but no cut-point achieves both high sensitivity and high specificity. The accuracy of detecting PCa can be increased by additional predictive factors and a combinations of markers. Evidence implies that a panel of kallikrein markers improves the specificity and reduces costs by eliminating unnecessary biopsies. Large, population-based studies have provided evidence that PSA can be used to predict PCa risk many years in advance, improve treatment selection and patient care, and predict the risk of complications and disease recurrence. However, definitive evidence is currently lacking as to whether PSA screening lowers PCa -specific mortality.

SUMMARY

PSA is still the main tool for early detection, risk stratification, and monitoring of PCa. However, PSA values are affected by many technical and biological factors. Instead of using a fixed PSA cut-point, using statistical prediction models and considering the integration additional markers may be able to improve and individualize PCa diagnostics. A single PSA measurement at early middle age can predict risk of advanced PCa decades in advance and stratify patients for intensity of subsequent screening.

Genetic variants and prostate cancer risk: candidate replication and exploration of viral restriction genes

The genetic variants underlying the strong heritable component of prostate cancer remain largely unknown. Genome-wide association studies of prostate cancer have yielded several variants that have significantly replicated across studies, predominantly in cases unselected for family history of prostate cancer. Additional candidate gene variants have also been proposed, many evaluated within familial prostate cancer study populations. Such variants hold great potential value for risk stratification, particularly for early-onset or aggressive prostate cancer, given the comorbidities associated with current therapies. Here, we investigate a Caucasian study population of 523 independent familial prostate cancer cases and 523 age-matched controls without a personal or family history of prostate cancer. We replicate identified associations at genome-wide association study loci 8q24, 11q13, and 2p15 (P = 2.9 x 10(-4) to P = 4.7 x 10(-5)), showing study population power. We also find evidence to support reported associations at candidate genes RNASEL, EZH2, and NKX3-1 (P = 0.031 to P = 0.0085). We further explore a set of candidate genes related to RNASEL and to its role in retroviral restriction, identifying nominal associations at XPR1 and RBM9. The effects at 8q24 seem more pronounced for those diagnosed at an early age, whereas at 2p15 and RNASEL the effects were more pronounced at a later age. However, these trends did not reach statistical significance. The effects at 2p15 were statistically significantly more pronounced for those diagnosed with aggressive disease.

The rs1447295 at 8q24 is a risk variant for prostate cancer in Taiwanese men

OBJECTIVES

To determine the association of a common variant, rs1447295, at the 8q24 region with prostate cancer (PCa) risk in Taiwanese men. Common variants at the 8q24 region have been shown to be associated with PCa risk. The variant rs1447295 has shown the strongest association. Most of the studies have been performed in European and American populations.

METHODS

This case-control study comprised 340 PCa patients and 337 controls. Genotyping was performed for rs14417295 to test for the association between its risk allele and PCa. Its association with disease stage, Gleason score, PSA level, and disease aggressiveness was also determined.

RESULTS

The A allele of rs1447295 was significantly associated with increased PCa risk (odds ratio = 1.49, 95% CI = 1.12-1.99). When compared with controls, the risk allele A was more frequent in PCa patients of both stages I+II (P = .028) and stages III+IV (P = .023), in patients of all Gleason scores (P < .05 in all subgroups), in patients with PSA levels >20 ng/mL (P = .001), and in patients with aggressive disease (P = .005).

CONCLUSIONS

This study confirmed that the A allele of rs1447295 is associated with a high risk of PCa in Taiwanese men.

Pathological outcomes associated with the 17q prostate cancer risk variants

PURPOSE

Recent studies have identified 2 distinct genetic variants along chromosome 17, including allele T of single nucleotide polymorphism rs4430796 on 17q12 and allele G of single nucleotide polymorphism rs1859962 on 17q24, that have been linked to prostate cancer risk. Less is known about tumor pathological features in carriers of these variants.

MATERIALS AND METHODS

Genotypes for regions 17q12 and 17q24 were determined in 759 white men with prostate cancer and compared to those in 790 healthy control volunteers using logistic regression. In patients with prostate cancer the Fisher exact or Kruskal-Wallis test was used as appropriate to assess the relationship(s) between clinical and pathological characteristics with 17q carrier status.

RESULTS

The frequency of the 17q12 and 17q24 genetic variants was significantly higher in patients with prostate cancer compared to that in controls (OR 1.32, 1.15, respectively). Of patients with prostate cancer 83% and 77% were carriers of the 17q12 and 17q24 variants as well as 75% and 75% of controls, respectively. Carriers of 17q12 risk variants were significantly more likely to have high grade disease using an additive best fit genetic model. In addition, there were trends toward adverse pathological features associated with 17q12 independent of the best fit genetic model.

CONCLUSIONS

Sequence variants along 17q12 and 17q24 were present in a significantly higher proportion of our prostate cancer cases than in our controls. Adverse pathological features, including higher Gleason grade and pathological stage, were more frequent in 17q12 carriers. Since these alleles may act in conjunction with variants on other chromosomes to influence prostate cancer risk, additional research is required to determine the cumulative associations of genetic risk variants with prognosis.

Evaluation of 8q24 and 17q risk loci and prostate cancer mortality

PURPOSE

Variants at chromosomal loci 8q24 and 17q are established risk factors for prostate cancer. Many studies have confirmed the findings for risk, but few have examined aggressiveness and other clinical variables in detail. Additionally, Gleason score is typically used as a surrogate for the primary end point of prostate cancer mortality. We investigated whether the 8q24 and 17q risk variants are associated with clinical variables as well as prostate cancer mortality.

EXPERIMENTAL DESIGN

In the Physicians' Health Study (1,347 cases and 1,462 controls), the Dana-Farber Harvard Cancer Center Specialized Program of Research Excellence (Gelb Center; 3,714 cases), and the Fred Hutchinson Cancer Research Center King County Case-Control Studies (1,308 cases and 1,266 controls), we examined eight previously identified 8q24 and 17q risk variants for association with prostate cancer mortality in men of European ancestry. We considered associations with other surrogate markers of prostate cancer aggressiveness, such as Gleason score, pathologic stage, prostate-specific antigen at diagnosis, and age at diagnosis.

RESULTS

Six of the eight variants were confirmed as prostate cancer risk factors. Several variants were nominally associated with age at diagnosis; when totaling all alleles for single nucleotide polymorphisms significantly associated with risk, each additional allele decreased age at diagnosis by an average of 6 months in the Physicians' Health Study (P = 0.0005) and 4 months in the Dana-Farber Harvard Cancer Center Specialized Program of Research Excellence (Gelb Center) cohort (P = 0.0016). However, there were no statistically significant associations with prostate cancer mortality.

CONCLUSIONS

Our results suggest that the 8q24 and 17q prostate cancer risk variants may influence age at diagnosis but not disease aggressiveness.