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.

Abstract 3226: Sleep disruption among prostate cancer survivors by metastatic disease status

Introduction: Advances in cancer screening, diagnosis, and treatment have resulted in an increasing population of cancer survivors, many of whom experience persistent cancer-related side effects. Multiple studies have found that cancer survivors report poorer sleep than the general population. More than 3 million men in the US are prostate cancer survivors, yet few existing studies have focused on sleep in this population, especially among men with metastatic disease. Thus, a better understanding of sleep problems among prostate cancer survivors could help characterize how sleep affects the quality of life among men with prostate cancer.

Aim: To describe sleep behaviors and problems among prostate cancer survivors overall and specifically among those with metastatic disease.

Methods: Self-reported sleep data, including sleep disruption, sleep apnea, and insomnia, were obtained from the 2018 Prostate Cancer Follow-up Survey (PCFS) administered to participants of the Health Professionals Follow-Up Study with a diagnosis of prostate cancer. We evaluated each item individually and calculated a score for clinical insomnia using the validated Women’s Health Initiative Insomnia Rating Scale (range 1-20; score &gt;10 indicative of clinically relevant insomnia). Descriptive analyses on sleep measures were conducted overall and stratified by metastatic disease. We utilized multivariable linear regression models to compare metastatic disease status and insomnia score, adjusting for age, race, body mass index, physical activity, smoking, and other health information.

Results: Of 2,431 men (median age: 83 years) who completed the 2018 survey, 87 had metastatic disease, de novo or men who progressed after diagnosis. Sleep disturbances were relatively common in this population. Among all men with prostate cancer, 33% (n=290) reported waking up several times a night five or more times a week, 14% (n=337) rated their sleep quality as restless, and 15% (n=368) reported a clinical diagnosis with sleep apnea. The Insomnia Rating Scale scores were relatively high among all prostate cancer survivors with a mean score of 9.0 (95% CI 6.0-12.0). Scores significantly differed by metastatic disease status and men with metastatic disease had scores that were 1.30 (95% CI 0.19-2.41) points higher than men without metastatic disease.

Conclusion: The growing global number of prostate cancer survivors with metastatic disease and the potentially high prevalence of negative cancer-related quality of life effects pose pressing challenges to health systems. Our findings suggest that sleep disturbances are common among prostate cancer survivors. Men with metastatic disease had poorer sleep overall and higher rates of clinical insomnia than men without metastatic disease. These results could highlight the importance of sleep among men with prostate cancer and could increase the clinical treatment of sleep problems.

Citation Format: Alaina H. Shreves, Lorelei Mucci, Unnur Valdimarsdottir, Sarah Markt, Kathryn Penney. Sleep disruption among prostate cancer survivors by metastatic disease status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3226.

Abstract 1574: Circadian clock gene expression and lethal prostate cancer outcomes

Background: Converging evidence points to a potential role of disruption of the circadian rhythm in prostate cancer progression. There is limited human data in prostate tissue examining the biological consequences of alterations in genes involved in circadian rhythm on outcomes among prostate cancer patients.

Methods: To test the hypothesis that tissue expression of circadian-related genes was associated with prostate cancer outcomes, we leveraged data from the Physicians' Health Study (PHS) and the Health Professionals Follow-Up Study (HPFS) prostate tumor cohorts. Whole transcriptome expression profiling was performed on 404 prostate cancer cases, including 113 lethal cases (metastatic disease or prostate cancer death) and 291 indolent cases (&gt;8 years from diagnosis without evidence of metastasis). Using logistic regression models, we assessed whether mRNA expression levels in tumor (N=404) or paired normal prostate tissue (N=202) of eleven circadian-related genes (AANAT, CLOCK, CRY1, CRY2, CSNK1E, MTNR1B, NPAS2, OPN4, PER1, PER2, PER3) were associated with lethal prostate cancer, stage (T2 vs. T3+), Gleason grade at diagnosis (&lt;8 vs. ≥8), and biomarkers of angiogenesis and apoptosis. We calculated odds ratios and 95% confidence intervals (95% CIs) per standard deviation increase in gene expression.

Results: Pathway analyses showed a statistically significant association between the eleven circadian genes and lethal disease (global test p-value = 5.1e-05). On an individual gene level, men with higher tumor expression of Period Circadian Regulator 1 (PER1) gene had a reduced risk of lethal disease, independent of grade and stage (OR: 0.75, 95% CI: 0.59-0.97). High tumor expression of PER1 (OR: 0.72, 95% CI: 0.57-0.91) and Cryptochrome Circadian Regulator 2 (CRY2) (OR: 0.79, 95% CI: 0.63-1.00) were associated with lower Gleason grade tumors. High tumor expression of PER1 was associated with lower levels of cell proliferation and lower levels of angiogenesis markers; Neuronal PAS Domain Protein 2 (NPAS2) was associated with markers of apoptosis. For none of the genes was expression in normal prostate tissue associated with lethal prostate cancer (global test p-value = 0.06).

Discussion: We found higher expression of several of the circadian related genes were associated with less aggressive prostate cancer features. In line with these findings, PER1 has been suggested to be a tumor suppressor in previous studies. This supports the idea that maintenance of circadian clock function may protect tumor progression.

Citation Format: Sarah C. Markt, Ericka Ebot, Iona Cheng, Lynne Wilkens, Ayesha Shafi, Karen Knudsen, Kathryn Penney, Lorelei Mucci, Travis Gerke. Circadian clock gene expression and lethal prostate cancer outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1574.

Abstract 4956: Transcriptome-wide association study identifies new prostate cancer susceptibility genes in the OncoArray data

Genome-wide association studies (GWAS) have identified over 150 genomic regions harboring risk variants for prostate cancer which explain one third of all familial risk. However, with some notable exceptions, the causal variants and target susceptibility genes at these risk loci have yet to be identified. Recent work has shown a strong overlap between loci associated with gene expression levels (eQTLs) in prostate tissue and GWAS loci, which suggests that the causal mechanism at a significant proportion of risk loci includes causal alleles that regulate expression levels of nearby susceptibility genes. While overlapping eQTLs with GWAS is a powerful method to prioritize susceptibility genes, it is often the case that multiple eQTLs co-localize at the GWAS risk region (due to linkage disequilibrium (LD) and correlations across transcript levels). This prohibits the identification of the true susceptibility gene as opposed to spurious co-localization at the same locus.

We recently leveraged gene expression imputation to perform transcriptome-wide association studies (TWAS) as a principled approach to measure the strength of association between gene expression and disease status. Here, we use imputed expression to identify new susceptibility genes for prostate cancer in the OncoArray GWAS data. We integrate gene expression data from more than 44 tissues across ~4,000 individuals with GWAS of prostate cancer from the OncoArray in ~140,000 individuals. Our approach identified 118 susceptibility genes for prostate cancer that reside in 90 independent loci across the genome. Of these, we report 7 genes located more than 0.5 Megabases away from any previously reported GWAS loci for prostate cancer, thus providing new risk loci. Second, we use TWAS to investigate genes previously reported as susceptibility genes for prostate cancer through overlaps of eQTL and GWAS. We find 36 (out of 86 previously reported genes) to be significant in TWAS. Overall, our findings highlight the power of integrating gene expression data with GWAS and provide testable hypotheses for future functional validation of prostate cancer risk.

Citation Format: Nicholas Mancuso, Wei Zheng, Kathryn Penney, The PRACTICAL Consortium, Zsofia Kote-Jarai, Christopher Haiman, Simon Gayther, Matthew Freedman, Bogdan Pasaniuc. Transcriptome-wide association study identifies new prostate cancer susceptibility genes in the OncoArray data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4956. doi:10.1158/1538-7445.AM2017-4956

Abstract 4952: Co-expression of pAKT and MYC is associated with aggressive disease in human prostate cancer

Introduction: AKT and MYC are amongst the most prevalent oncogenes in prostate cancer (PCa). MYC cooperates with activated AKT in pre-clinical, genetically engineered in vivo models accelerating disease progression and increasing resistance to therapy. However, the clinical relevance of phosphoAKT/MYC co-expression in human prostate tumors remains unknown.

Experimental Procedures: A prospective cohort (Physicians’ Health Study and Health Professionals Follow-up Study) of 578 men with PCa with a mean 13-year follow up was used. Protein expression of MYC and phosphoAKT (Serine 473) was characterized by immunohistochemistry on tissue microarrays. pAKT and MYC expression was analyzed using the Cri Vectra/InForm multispectral analysis platform. The InForm software package was trained to segment PCa regions only (i.e., no stromal regions were included in the analysis). We used quantile normalization to adjust for the potential batch effects of protein expression staining across each of the tissue microarrays using the limma package R. The continuous score for pAKT and MYC were divided into quartiles and assigned a value of 1, 2, 3 or 4 for low (1), moderate (2 or 3) and high staining (4). Spearman correlations between pAKT, MYC and the clinico-pathological data were calculated.

Results: High pAKT and High MYC were co-expressed in 10% of patients. (Quartile 4). Also 10% were negative or weakly positive for both pAKT and MYC (Quartile 1). Only 3% of the High pAKT patients had weak or no expression of MYC and 4% of High_MYC patients had Low pAKT expression. The majority of patients were distributed in the Quartiles 2 and 3 (73%). Importantly, only High pAKT and High pMYC co-expressors were associated with tumor stage (pT3 or pT4) (p = 0.03), high Gleason Score (p = 0.021) and presence of metastatic disease (p = 0.011). GEP analysis showed that the same patients exhibited up-regulation of genes involved in cell invasion/migration capacity and stromal remodeling.

Conclusions: Co-expression of AKT and MYC is associated poor clinical outcome in PCa patients. Gene expression profiling suggest that concomitant activation of AKT and MYC results in the activation of pathways associated with an invasive phenotype.

Citation Format: Nelma Pértega-Gomes, Svitlana Tyekucheva, Kathryn Penney, Giorgia Zadra, Lorelei A. Mucci, Massimo Loda. Co-expression of pAKT and MYC is associated with aggressive disease in human prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4952.

Precision prevention of TMPRSS2:ERG prostate cancer

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Background: Increased integration of tumor biomarker data into prostate cancer epidemiology studies is needed to identify molecular subtypes that underlie its etiology and progression. We hypothesize that the TMPRSS2:ERG gene fusion is a unique prostate cancer subtype that is etiologically distinct from cancers lacking TMPRSS2:ERG. Methods: We leveraged the Physicians’ Health Study and Health Professionals Follow-up Study cohort data on pre- and post-diagnostic lifestyle factors, inherited genetic variants, circulating biomarkers, and clinical data and follow-up for 30 years. We have a tumor repository of men with prostate cancer and tumor tissue microarrays. Using immunohistochemistry, we characterized TMPRSS2:ERG status for 1,491 incident prostate cancer cases in these cohorts, and also have biomarker data on a range of additional markers from immunohistochemistry and mRNA expression profiling. Results: Fifty percent of prostate cancer cases were ERG-positive. ERG-positive cancers show much higher expression of insulin/IGF signaling, PTEN loss, higher VDR expression, as well as expression of mismatch repair genes. In contrast, ERG-negative prostate cancer is characterized by increased presence of chronic inflammation and atrophy. We found higher pre-diagnostic free testosterone levels, but not other sex hormones, were associated with increased risk of ERG-positive (OR = 1.4, 95% CI = 1.0-1.8) but not ERG-negative disease (OR = 0.9, 95% CI = 0.7-1.2). Of 39 known genetic risk loci, six were significantly associated (p < 0.05) with ERG+ versus ERG- cancer (2 expected by chance). Prostate cancer risk factors such as taller height (an indicator of growth factors in puberty) are uniquely associated with ERG-positive prostate cancer. Moreover, we observe a complex interaction of components of insulin/IGF and ERG-status on prostate cancer mortality. Conclusions: TMPRSS2:ERG is a highly prevalent somatic event in prostate cancer that likely defines a unique molecular subtype of this common disease. Understanding the differences between these two prostate cancer subtypes may enhance opportunities for prevention.

Familial risk and heritability of genitourinary cancers in the Nordic Twin Cohorts

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Background: Twin studies estimate familial risk and heritability by leveraging the unique genetic relatedness of twins. We analyzed data from the Nordic Twin Study to investigate the genetic underpinnings of risk of genitourinary cancers. Methods: The cohort included 202,868 monozygotic (MZ) and same-sex dizygotic (DZ) twins from nationwide registries with follow-up via cancer registries. We examined cancers of the prostate, bladder, kidney and testes, and estimated familial risk, risk of a specific cancer in a twin, given that his co-twin was diagnosed with the same cancer, and heritability, the proportion of variation in cancer risk due to genetic differences. Statistical models used time-to-event analyses and accounted for censoring and competing risk of death. Results: During 32 years of follow-up, 5,041 cases of genitourinary cancer were diagnosed. The cumulative incidences in the cohort overall were 10.5% for prostate, 2.2% for bladder, 0.8% for kidney and 0.5% for testes. The strongest familial effects were found for testicular cancer. The familial risks of testicular cancer were 6% for DZ and 14% for MZ twins, i.e. a 12-fold and 28-fold higher risk for DZ and MZ twins, respectively, when their twin was also diagnosed with testicular cancer. Familial risk was also elevated for prostate, bladder, and kidney cancer and showed higher estimates among MZ than DZ twins. Statistically significant estimates of heritability were observed for prostate (57%) and kidney (38%) cancer, while testicular cancer showed evidence of both genetic (37%) and shared environmental (24%) effects. Conclusions: Familial risk estimates provide evidence of significant excess risks for individuals whose siblings develop genitourinary cancers. The higher concordance in MZ vs. DZ twins translated to strong heritability estimates for these malignancies. Results from this study have the potential to be directly translated to clinical practice and genetic counseling, and provide a context for the findings from genome wide association studies.

Discovery and validation of a 30-gene expression signature to identify prostate cancer patients who are candidates for active surveillance

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Background: Considerable attention has been devoted to the search for biomarkers of aggressive prostate cancer. While many promising markers have been proposed, it is often unclear whether their ability to risk classify is adequate to reduce overtreatment of indolent cancers. We present and validate a gene expression signature that is highly specific for indolent disease and that, when combined with Gleason, improves upon the prognostic power of Gleason alone. Methods: A 30-gene signature of indolent disease was derived from a case-control sample of men (n=254) from the Health Professionals Follow-Up Study (HPFS) who were followed prospectively from cancer diagnosis for a median of 13.7 years. Cases were defined as men with prostate cancer who experienced a metastatic event or died of cancer during follow-up, while indolent controls survived at least 8 years without metastases. Whole-transcriptome gene expression was quantified from archival formalin-fixed, paraffin-embedded (FFPE) tumor tissue specimens acquired at prostatectomy. Genes were selected by a novel analytic strategy that maximizes a partial area under the curve (pAUC) to accurately identify indolent tumors. We validated the signature in two independent cohorts: the Physicians’ Health Study (PHS; n=150) and a Swedish Watchful Waiting cohort (WW; n=253) with respective median follow-up times of 14.4 and 9.0 years. Results: When compared to a model with Gleason alone, application of the signature to both validation data sets significantly improved prognostic accuracy as measured by pAUC (p=0.003 in PHS and p<0.001 in WW). Performance was particularly strong among men diagnosed with Gleason 7, where unit standard deviation increases in the signature score were associated with odds ratios of indolence of 5.24 (95% CI 2.21-15.75; p<0.001) and 2.37 (95% CI 1.45-4.19; p=0.001) in the PHS and WW cohorts, respectively. Conclusions: We present a signature of indolent prostate cancer that adds prognostic information beyond Gleason and has the potential to guide men to active surveillance and avoid overtreatment. Validation across both treated and untreated cohorts supports the discovery of a robust signature.

Abstract A60: Vitamin D related genetic variation, plasma vitamin D, and risk of lethal prostate cancer

Background: The association of vitamin D status with prostate cancer is controversial, with no association observed for overall incidence, but a potential link with lethal disease.

Methods: We assessed prediagnostic plasma 25-hydroxyvitamin D [25(OH)D] and variation in vitamin D related genes and the risk of lethal prostate cancer using a prospective case-control study nested within the Health Professionals Follow-up Study. We included 1328 incident cases diagnosed following blood draw (1993–95) and 1331 controls. Men with prostate cancer were followed through March 2011 for lethal outcomes (n=111). We selected 97 linkage disequilibrium tagSNPs to represent common genetic variation across seven vitamin D related genes (CYP27A1, CYP2R1, CYP27B1, GC, CYP24A1, RXRA, VDR). We used a logistic kernel machine test to assess the multimarker pathway global association for ‘SNP-sets’ defined by the seven genes with prostate cancer.

Results: Higher levels of 25(OH)D were associated with about half the risk of lethal prostate cancer (OR comparing extreme quartiles: 0.45; 95% CI:0.25–0.81). This finding did not vary by time from blood draw to diagnosis. We found no significant association of 25(OH)D with overall prostate cancer risk(OR comparing extreme quartiles: 1.05; 95% CI: 0.85–1.30). The total vitamin D pathway SNP-set (seven genes) as well as SNP-sets defined by the individual genes (VDR, RXRA, or CYP27A1) were nominally associated with lethal prostate cancer risk (p&lt;0.05), but not overall prostate cancer (p=0.41). Conclusions: In this large prospective study, plasma 25(OH)D and common variation across vitamin D pathway genes were associated with lethal prostate cancer risk. Studies of vitamin D and prostate cancer should focus on lethal disease.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):A60.

Immunohistochemical expression of BRCA1 and lethal prostate cancer

BRCA1 functions as a tumor suppressor; recent work suggests that BRCA1 may also induce cell cycle arrest to allow for DNA repair. We hypothesized that BRCA1 expression in prostate tumor tissue may be associated with prostate cancer progression through regulation of the cell cycle. We used immunohistochemistry to evaluate BRCA1 protein expression in archival tumor samples from 393 prostate cancer cases in the Physicians' Health Study. The men were followed prospectively from diagnosis to development of metastases and mortality. Fifteen percent of tumors stained positive for BRCA1. BRCA1-positive tumors had substantially increased tumor proliferation index compared with negative tumors (47.0 Ki67-positive nuclei versus 10.3, P = 0.0016) and were more likely to develop lethal cancer compared with BRCA1-negative tumors (hazard ratio, 4.6; 95% confidence interval, 2.4-8.7). These findings strengthen the hypothesis that BRCA1 plays a role in cell cycle control and show that BRCA1 is a marker of clinical prostate cancer prognosis. Cancer Res; 70(8); 3136-9. (c)2010 AACR.

Abstract PR-01: Vitamin D receptor expression is inversely associated with prostate cancer progression

Background: Vitamin D is inversely associated with risk of several malignancies. Circulating vitamin D interacts with the vitamin D receptor (VDR) at the cellular level to inhibit proliferation, increase apoptosis and decrease angiogenesis. Thus, although vitamin D levels appear to be unrelated to total prostate cancer incidence, VDR levels in tumor tissue may influence prostate cancer prognosis.

Methods: We examined the immunohistochemical expression of VDR on archival tumor tissue from 841 prostate cancer cases diagnosed between 1982 and 2004 within two ongoing, prospective cohorts: the Physicians' Health Study and Health Professionals Follow-up Study. VDR expression was measured quantitatively using the CRi Vectra™ system. We used Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association of VDR expression with lethal prostate cancer (N=73) through 2008. On a subset of cases, we also examined correlation of tumor VDR expression with circulating 25(OH)D3 and 1alpha,25(OH)2D3 measured at baseline (N=84) in 1982 and two SNPs in VDR: Fok1 and bsm1 (N=140).

Results: Men with high tumor VDR expression had significantly lower Gleason score, lower prostate specific antigen (PSA) levels at diagnosis, and were less likely to have advanced tumor stage (p=0.008, p=0.012, p=0.001, respectively). Compared to the lowest quartile, men in the highest quartile of VDR expression were at significantly lower risk of developing lethal prostate cancer (age-adjusted HRs across quartiles Q2=0.95, 95% CI: 0.51–1.79; Q3=0.93, 95% CI: 0.49–1.76; Q4 = 0.23, 95% CI:0.09–0.55). This association was attenuated (HRQ4vsQ1 = 0.42, 95% CI: 0.16–1.09) after further adjustment for pathological tumor stage, Gleason grade, and PSA level at diagnosis. Tumors expressing high levels of VDR had modest downregulation of cell proliferation as measured by Ki67 (r=-0.11). Moreover, expression of estrogen receptor alpha (r=0.40, p&lt;0.001) and androgen receptor (r=0.41, p&lt;0.001) were positively correlated with VDR expression. Neither prediagnostic plasma vitamin D levels nor gene variants in VDR were associated with VDR protein expression in tumors.

Conclusion: In this large prospective study, men with tumors that demonstrated upregulation of VDR had significantly improved clinical features and reduced risk of lethal prostate cancer. In line with experimental studies, the positive correlation between VDR expression, and androgen receptor and estrogen receptor provides evidence that that VDR acts in an androgen- and/or estrogen-dependent manner. These data highlight the potential role of the vitamin D system in preventing prostate cancer progression.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):PR-01.

TGFB1 and TGFBR1 polymorphisms and breast cancer risk in the Nurses' Health Study

BACKGROUND

Transforming growth factor beta 1 (TGFB1) forms a signaling complex with transforming growth factor beta receptors 1 and 2 and has been described as both a tumor suppressor and tumor promoter. Single nucleotide polymorphisms in TGFB1 and a microsatellite in TGFBR1 have been investigated for association with risk of breast cancer, with conflicting results.

METHODS

We examined polymorphisms in the promoter region of the TGFB1 gene as well as the TGFBR1*6A microsatellite in the Nurses' Health Study cohort.

RESULTS

No overall associations between the L10P polymorphism of TGFB1 or the TGFBR1 microsatellite were detected. However, we observed an inverse association between the -509 C/T polymorphism of TGFB1 (p-trend = 0.04), which was stronger and more significant among women with estrogen receptor positive breast cancer.

CONCLUSION

Polymorphisms in the promoter region of TGFB1 are not likely to be associated with large increases in breast cancer risk overall among Caucasian women.

Common genetic variation at PTEN and risk of sporadic breast and prostate cancer

PTEN frequently shows loss of heterozygosity in breast and prostate cancers, and mutations in this gene are responsible for Cowden disease, a rare Mendelian syndrome that includes breast cancer as part of its phenotype. Thus, PTEN serves as a candidate susceptibility gene for both breast and prostate cancer risk. Whether common inherited variation (either coding or noncoding) at the PTEN locus contribute to nonfamilial, sporadic breast and prostate cancer risk is not known. In this study, we employed a linkage disequilibrium-based approach to test for association between common genetic variation at the PTEN locus and breast and prostate cancer risk in African-American, Native Hawaiian, Japanese, Latina, and White men and women in the Multiethnic Cohort Study. We genotyped 17 common single nucleotide polymorphisms (SNP; >/=5% frequency in at least one ethnic group) spanning the PTEN gene to define the common alleles in these populations. These SNPs were in strong linkage disequilibrium, indicating that our survey captured most of the common sequence variation across this locus. Eight tagging SNPs were selected to predict the common PTEN haplotypes (>/=0.05 frequency) in these populations (two additional tagging SNPs were required for African Americans). These SNPs were evaluated in a breast cancer case-control study (cases, n = 1,615; controls, n = 1,962) and prostate cancer case-control study (cases, n = 2,320; controls, n = 2,290) nested within the Multiethnic Cohort Study. Multiple testing was explicitly accounted for by applying a permutation-based framework. We found no strong association with any common haplotype in relation to breast or prostate cancer risk. In summary, our results show that common variants in PTEN do not substantially influence risk of these two common cancers.

Admixture mapping identifies 8q24 as a prostate cancer risk locus in African-American men

A whole-genome admixture scan in 1,597 African Americans identified a 3.8 Mb interval on chromosome 8q24 as significantly associated with susceptibility to prostate cancer [logarithm of odds (LOD) = 7.1]. The increased risk because of inheriting African ancestry is greater in men diagnosed before 72 years of age (P < 0.00032) and may contribute to the epidemiological observation that the higher risk for prostate cancer in African Americans is greatest in younger men (and attenuates with older age). The same region was recently identified through linkage analysis of prostate cancer, followed by fine-mapping. We strongly replicated this association (P < 4.2 x 10(-9)) but find that the previously described alleles do not explain more than a fraction of the admixture signal. Thus, admixture mapping indicates a major, still-unidentified risk gene for prostate cancer at 8q24, motivating intense work to find it.

Failure to detect Chlamydia pneumoniae in coronary atheromas of patients undergoing atherectomy

To further investigate a proposed relationship between Chlamydia pneumoniae and coronary heart disease, coronary atheromas were collected from patients undergoing percutaneous atherectomy. Fifty-eight atheroma specimens were examined by culture and polymerase chain reaction (PCR) and 22 by electron microscopy. All were negative for C. pneumoniae, except a single specimen that was PCR-positive. These results differ from studies in other populations, in which this organism was identified by nonculture methods within coronary atheromas obtained at autopsy. Anti-C. pneumoniae antibody titers from 65 of the patients were compared with those of 28 asymptomatic controls. IgG titers were higher in controls than in patients. There is no evidence that C. pneumoniae exists within atheromas in this study population, nor does seroprevalence correlate with the presence of coronary disease in these patients.