Sheri Trudeau

Inflammation and preneoplastic lesions in benign prostate as risk factors for prostate cancer

Benign changes ranging from atrophy and inflammation to high-grade prostatic intraepithelial neoplasia (HGPIN) are common findings on prostate core needle biopsies. Although atrophy and inflammation may be precursors of prostate cancer, only HGPIN is currently recommended to be included in surgical pathology reports. To determine whether these benign findings increase prostate cancer risk, we conducted a case–control study nested within a historical cohort of 6692 men with a benign prostate specimen collected between 1990 and 2002. The analytic sample included 574 case–control pairs comprised of cases diagnosed with prostate cancer a minimum of 1 year after cohort entry and controls matched to cases on date and age at cohort entry, race, and type of specimen. The initial benign specimen was reviewed for presence of HGPIN, atrophy (simple, lobular, and partial) and inflammation (glandular and/or stromal). HGPIN significantly increased risk for prostate cancer (odds ratio (OR)=2.00; 95% confidence interval (CI)=1.25–3.20). Inflammation within the stromal compartment was associated with decreased risk (OR=0.66; CI=0.52–0.84), and diffuse stromal inflammation of severe grade had the strongest inverse association with risk (OR=0.21; CI=0.07–0.62). In a model adjusted for prostate-specific antigen (PSA) level at cohort entry and inflammation, simple atrophy was associated with a 33% increased prostate cancer risk that was marginally significant (P=0.03). Clinicians should consider patterns and extent of inflammation when managing high-risk patients with negative biopsy results. Identifying benign inflammatory processes that underlie high PSA levels would help to reduce the number of unnecessary repeated prostate biopsies.

Hepatitis C treatment failure is associated with increased risk of hepatocellular carcinoma.

Sustained virological response (SVR) to antiviral therapy for hepatitis C (HCV) reduces risk of hepatocellular carcinoma (HCC), but there is little information regarding how treatment failure (TF) compares to lack of treatment. We evaluated the impact of treatment status on risk of HCC using data from the Chronic Hepatitis Cohort Study (CHeCS–an observational study based in four large US health systems, with up to 7 years of follow‐up on patients). Multivariable analyses were used to adjust for bias in treatment selection, as well as other covariates, followed by sensitivity analyses. Among 10 091 HCV patients, 3681 (36%) received treatment, 2099 (57%) experienced treatment failure (TF), and 1582 (43%) of these achieved sustained virological response (SVR). TF patients demonstrated almost twice the risk of HCC than untreated patients [adjusted hazard ratio (aHR) = 1.95, 95% confidence interval (CI) 1.50–2.53]; this risk persisted across all stages of fibrosis. Several sensitivity analyses validated these results. Although African Americans were at increased risk of treatment failure, they were at lower risk for HCC and all‐cause mortality compared to White patients. SVR patients had lower risk of HCC than TF patients (aHR = 0.48, CI 0.31–0.73), whereas treatment – regardless of outcome – reduced all‐cause mortality (aHR = 0.45, CI 0.34–0.60 for SVR patients; aHR = 0.78, CI 0.65–0.93 for TF patients).

Elevated polycyclic aromatic hydrocarbon-DNA adducts in benign prostate and risk of prostate cancer in African Americans

Carcinogen-DNA adducts, a marker of DNA damage, are capable of inducing mutations in oncogenes and tumor suppressor genes, resulting in carcinogenesis. We have shown previously that polycyclic aromatic hydrocarbon (PAH)-DNA adduct levels in prostate cancer cases vary by cellular histology and that higher adduct levels are associated with biochemical recurrence. A nested case-control study was conducted in a historical cohort of 6692 men with histopathologically benign prostate specimens. PAH-DNA adduct levels were determined by immunohistochemistry in benign prostate specimens from 536 prostate cancer case-control pairs (59% White and 41% African American). We estimated the overall and race-stratified risk of subsequent prostate cancer associated with higher adduct levels. Prostate cancer risk for men with elevated adduct levels (defined as greater than control group median) was slightly increased [odds ratio (OR) = 1.28, 95% confidence interval (CI) = 0.98-1.67, P = 0.07]. After race stratification, elevated adduct levels were significantly associated with increased risk in African American men (OR = 1.56, CI = 1.00-2.44, *P = 0.05) but not White men (OR = 1.14, CI = 0.82-1.59, P = 0.45). Elevated PAH-DNA adduct levels were significantly associated with 60% increased risk of prostate cancer among cases diagnosed 1-4 years after cohort entry (OR = 1.60, CI = 1.07-2.41) with a greater risk observed in African Americans within the first 4 years of follow-up (OR = 4.71, CI = 1.97-11.26, ***P = 0.0005). Analyses stratified by age or tumor grade revealed no additional significant heterogeneity in risk. Increased prostate cancer risk associated with high PAH-DNA adduct levels in benign prostate was found only in African Americans; risk was greatest within 4 years of follow-up, possibly reflecting a carcinogenic process not yet histologically detectable.

Admixture Fine-Mapping in African Americans Implicates XAF1 as a Possible Sarcoidosis Risk Gene

Sarcoidosis is a complex, multi-organ granulomatous disease with a likely genetic component. West African ancestry confers a higher risk for sarcoidosis than European ancestry. Admixture mapping provides the most direct method to locate genes that underlie such ethnic variation in disease risk. We sought to identify genetic risk variants within four previously-identified ancestry-associated regions—6p24.3–p12.1, 17p13.3–13.1, 2p13.3–q12.1, and 6q23.3–q25.2—in a sample of 2,727 African Americans. We used logistic regression fit by generalized estimating equations and the MIX score statistic to determine which variants within ancestry-associated regions were associated with risk and responsible for the admixture signal. Fine mapping was performed by imputation, based on a previous genome-wide association study; significant variants were validated by direct genotyping. Within the 6p24.3–p12.1 locus, the most significant ancestry-adjusted SNP was rs74318745 (p = 9.4*10−11), an intronic SNP within the HLA-DRA gene that did not solely explain the admixture signal, indicating the presence of more than a single risk variant within this well-established sarcoidosis risk region. The locus on chromosome 17p13.3–13.1 revealed a novel sarcoidosis risk SNP, rs6502976 (p = 9.5*10−6), within intron 5 of the gene X-linked Inhibitor of Apoptosis Associated Factor 1 (XAF1) that accounted for the majority of the admixture linkage signal. Immunohistochemical expression studies demonstrated lack of expression of XAF1 and a corresponding high level of expression of its downstream target, X-linked Inhibitor of Apoptosis (XIAP) in sarcoidosis granulomas. In conclusion, ancestry and association fine mapping revealed a novel sarcoidosis susceptibility gene, XAF1, which has not been identified by previous genome-wide association studies. Based on the known biology of the XIAP/XAF1 apoptosis pathway and the differential expression patterns of XAF1 and XIAP in sarcoidosis granulomas, we suggest that this pathway may play a role in the maintenance of sarcoidosis granulomas.

Performance of HLA allele prediction methods in African Americans for class II genes HLA-DRB1, −DQB1, and –DPB1

BackgroundThe expense of human leukocyte antigen (HLA) allele genotyping has motivated the development of imputation methods that use dense single nucleotide polymorphism (SNP) genotype data and the region’s haplotype structure, but the performance of these methods in admixed populations (such as African Americans) has not been adequately evaluated. We compared genotype-based—derived from both genome-wide genotyping and targeted sequencing—imputation results to existing allele data for HLA–DRB1, −DQB1, and –DPB1.ResultsIn European Americans, the newly-developed HLA Genotype Imputation with Attribute Bagging (HIBAG) method outperformed HLA*IMP:02. In African Americans, HLA*IMP:02 performed marginally better than HIBAG pre-built models, but HIBAG models constructed using a portion of our African American sample with both SNP genotyping and four-digit HLA class II allele typing had consistently higher accuracy than HLA*IMP:02. However, HIBAG was significantly less accurate in individuals heterozygous for local ancestry (p ≤0.04). Accuracy improved in models with equal numbers of African and European chromosomes. Variants added by targeted sequencing and SNP imputation further improved both imputation accuracy and the proportion of high quality calls.ConclusionCombining the HIBAG approach with local ancestry and dense variant data can produce highly-accurate HLA class II allele imputation in African Americans.

Methylation of the RARB Gene Increases Prostate Cancer Risk in Black Americans

PURPOSE Gene promoter hypermethylation may be useful as a biomarker for cancer risk in histopathologically benign prostate specimens. MATERIALS AND METHODS We performed a nested case-control study of gene promoter methylation status for 5 genes (APC, RARB, CCND2, RASSF1 and MGMT) measured in benign biopsy specimens from 511 prostate cancer case-control pairs. We estimated the overall and race stratified risk of subsequent prostate cancer associated with methylation status. RESULTS On race stratified analysis RARB methylation was associated with a higher cancer risk in black American men (OR 2.18, 95% CI 1.39-3.44). APC methylation was associated with an increased risk of high grade tumors (OR 2.43, 95% CI 1.20-4.90), which was higher in black than in white men (OR 3.21 vs 2.04). In cases RARB and APC gene methylation in benign prostate samples persisted in matched malignant specimens. In black cases the combined risk associated with RARB and APC methylation (OR 3.04, 95% CI 1.44-6.42) was greater than the individual risk of each gene and significantly different from that in white cases (OR 1.14, 95% CI 0.56-2.30). CONCLUSIONS RARB gene methylation in histopathologically benign prostate samples was associated with a statistically significant increased risk of subsequent prostate cancer in black men. Methylation data on additional genes may improve risk stratification and clinical decision making algorithms for cancer screening and diagnosis.

2-Amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP)-DNA adducts in benign prostate and subsequent risk for prostate cancer

Despite convincing evidence that 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP)—a heterocyclic amine generated by cooking meats at high temperatures—is carcinogenic in animal models, it remains unclear whether PhIP exposure leads to increased cancer risk in humans. PhIP‐DNA adduct levels were measured in specimens from 534 prostate cancer case‐control pairs nested within a historical cohort of men with histopathologically benign prostate specimens. We estimated the overall and race‐stratified risk of subsequent prostate cancer associated with higher adduct levels. PhIP‐DNA adduct levels in benign prostate were significantly higher in Whites than African Americans (0.274 optical density units (OD) ±0.059 vs. 0.256 OD ±0.054; p<0.0001). Prostate cancer risk for men in the highest quartile of PhIP‐DNA adduct levels was modestly increased [odds ratio (OR) = 1.25; 95% confidence interval (CI) = 0.76–2.07]. In subset analyses, the highest risk estimates were observed in White patients diagnosed more than 4 years after cohort entry (OR = 2.74; 95% CI = 1.01–7.42) or under age 65 (OR = 2.80; 95% CI = 0.87–8.97). In Whites, cancer risk associated with high‐grade prostatic intraepithelial neoplasia combined with elevated PhIP‐DNA adduct levels (OR = 3.89; 95% CI = 1.56–9.73) was greater than risk associated with either factor alone. Overall, elevated levels of PhIP‐DNA adducts do not significantly increase prostate cancer risk. However, our data show that White men have higher PhIP‐DNA adduct levels in benign prostate tissue than African American men, and suggest that in certain subgroups of White men high PhIP‐DNA adduct levels may predispose to an increased risk for prostate cancer.

Association of HLA-DRB1 with Sarcoidosis Susceptibility and Progression in African Americans

HLA-DRB1 is a sarcoidosis risk gene, and the *03:01 allele is strongly associated with disease resolution in European sarcoidosis cases. Whereas the HLA-DRB1 variation is associated with sarcoidosis susceptibility in African Americans, DRB1 risk alleles are not as well defined, and associations with disease resolution have not been studied. Associations between genotyped and imputed HLA-DRB1 alleles and disease susceptibility/resolution were evaluated in a sample of 1,277 African-American patients with sarcoidosis and 1,467 control subjects. In silico binding assays were performed to assess the functional significance of the associated alleles. Increased disease susceptibility was associated with the HLA-DRB1 alleles *12:01 (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.65-2.69; P = 3.2 × 10(-9)) and *11:01 (OR, 1.69; 95% CI, 1.42-2.01; P = 3.0 × 10(-9)). The strongest protective association was found with *03:01 (OR, 0.56; 95% CI, 0.44-0.73; P = 1.0 × 10(-5)). The African-derived allele *03:02 was associated with decreased risk of persistent radiographic disease (OR, 0.52; 95% CI, 0.37-0.72; P = 1.3 × 10(-4)), a finding consistent across the three component studies comprising the analytic sample. The DRB1*03:01 association with disease persistence was dependent upon local ancestry, with carriers of at least one European allele at DRB1 at a decreased risk of persistent disease (OR, 0.36; 95% CI, 0.14-0.94; P = 0.037). Results of in silico binding analyses showed that DRB1*03:01 consistently demonstrated the highest binding affinities for six bacterial peptides previously found in sarcoidosis granulomas, whereas *12:01 displayed the lowest binding affinities. This study has identified DRB1*03:01 and *03:02 as novel alleles associated with disease susceptibility and course in African Americans. Further investigation of DRB1*03 alleles may uncover immunologic factors that favor sarcoidosis protection and resolution among African Americans.

Changing trends in complications of chronic hepatitis C

Chronic hepatitis C virus (HCV)‐related complications have increased over the past decade.

Race, Age, and Geography Impact Hepatitis C Genotype Distribution in the United States

Goals: To determine the impact of geography and patient characteristics on hepatitis C virus (HCV) genotype and subtype distribution in a large sample of patients under routine clinical care Background: HCV genotype impacts disease course and response to treatment. Although several studies have reported genotype distribution within specific US populations, there are no comprehensive descriptions in large, geographically diverse cohorts. Study: Using data from the Chronic Hepatitis Cohort Study, we present the distribution of HCV genotypes (GT) and subtypes (ST) among a racially diverse cohort of over 8000 HCV-infected patients from four large US health systems. Results: Genotype distribution varied significantly by geographic and demographic factors. In age-adjusted analyses, African American patients had significantly higher prevalence of GT1 (85%) than other racial categories, largely driven by a markedly higher proportion of GT1 subtype b (∼34%) than in Asian/other (24%) and white (21%) patients. GT3 represented an increasing proportion of infections as birth decade progressed, from 4% in patients born before 1946 to 18% of those born after 1976. Within the cohort of “living/uncured” patients, highly elevated alanine aminotransferase (>2 times the upper limit of normal) was significantly more common in GT3 patients, whereas Fibrosis-4 Index scores indicative of cirrhosis were most common in the combined group of GT4&6 patients. Conclusion: Distribution of HCV genotypes and subtypes in the United States is more variable than suggested by previous national-level estimates and single-center studies. “Real-world” prevalence data may improve targeting of prevention, screening, and treatment efforts for hepatitis C.