Incidence Trends in Upper Gastrointestinal Cancer in Young Adults: A Nationwide Time-Trend Analysis Using 2001-2019 US Cancer Statistics Databases.

INTRODUCTION: Upper gastrointestinal (UGI) cancers, comprising malignancies of the esophagus, stomach, duodenum, pancreas, liver, biliary tract, and gallbladder, are the second leading cause of cancer-related mortality in the United States and are associated with significant comorbidities. Recent studies show a disproportionate rise in pancreatic and stomach cancer among young adults. This study aims to use a nationwide, population-based cohort to (i) evaluate the trend of all UGI cancer as an aggregate and (ii) examine the role of demographics, histology, and tumor stage in UGI cancer incidence among young adults. METHODS: Individuals diagnosed with UGI cancer in the United States from 2001 to 2019 were identified and obtained from the Surveillance, Epidemiology, and End Results-National Program of Cancer Registries database. The primary outcomes were incidence rates of UGI cancer (calculated per 100,000, age-adjusted to the year 2000 US population), stratified by sex and age (< 55 years for young adults and ≥ 55 years for older adults). Trends, annual percentage change, and average annual percentage change were calculated using the parametric method. Sensitivity analysis was performed according to primary site and histology; further analysis examining race and cancer stage was performed in the young adult subgroup. RESULTS: A total of 2,333,161 patients with UGI cancer were identified. Most cases were male, and 14.3% were < 55 years of age. Incidence of UGI cancer increased most in women younger than 55 years, driven primarily by pancreatic and stomach cancers, as well as neuroendocrine tumor and gastrointestinal stromal tumor histology. African American race and localized tumors and malignancy with distant spread are also contributing to the disparate increase among young women. UGI mortality rates have not changed significantly in young adults. DISCUSSION: The overall incidence rate of upper gastrointestinal cancer is increasing significantly in young women compared with men. Increased endoscopic procedures and disparate exposure to risk factors are likely contributing to these trends.

Analysis of the Application of Professional Society Screening Guidelines for Colorectal Polyposis Syndromes at a Single Institution.

Several professional society guidelines suggest germline genetic testing for colorectal polyposis syndromes in patients with ≥10 lifetime adenomatous polyps. This study evaluated the factors associated with genetic testing decisions and outcomes when germline testing was recommended per guidelines. Surgical archives revealed 145 patients with a recommendation for germline genetic polyposis testing based on guidelines. Demographic data and medical history were collected to examine their association with testing decisions and results. Germline genetic testing was ordered in 90 out of 145 patients and was ordered in younger patients with more lifetime adenomas. Pathogenic alterations were detected in 12 out of 53 patients who completed testing. Younger ages and higher numbers of lifetime adenomas were not associated with the detection of germline genetic alterations. In fact, patients with a pathogenic germline alteration had higher median ages and fewer lifetime adenomas than those without an alteration. Half of the 12 patients with a pathogenic germline mutation were not White non-Hispanic, although White non-Hispanic patients comprised 75.5% of those tested. This study supports the 10 adenomatous polyp threshold for recommending germline genetic polyposis testing, as an alteration was detected in a sizable proportion (>20%) of patients tested. Although a younger age and a higher number of lifetime adenomas were associated with an increased likelihood of ordered tests, no evidence was found to support these additional factors in testing decisions.

Markedly increased duodenal villous surface apoptosis in patients taking pre-exposure prophylaxis (PrEP) against human immunodeficiency virus.

AIMS: Pre-exposure prophylaxis (PrEP) consists of combination antiretroviral therapy and is increasingly utilized to prevent human immunodeficiency virus (HIV) in high-risk populations. Two index cases noted during routine care showed markedly increased duodenal villous surface apoptosis in patients on PrEP. We sought to examine the prevalence of this finding and identify any clinicopathologic correlations. METHODS: Gastrointestinal biopsy specimens from 23 male patients aged 18-40 years taking PrEP and 23 control patients were reviewed. Patients with HIV, inflammatory gastrointestinal diseases, and celiac disease were excluded. Apoptoses were counted on surface epithelium and deep crypts. The highest apoptotic body count per tissue fragment was recorded. Clusters were defined as groups of ≥5 apoptoses. Apoptotic counts between patients taking PrEP and controls were compared using t-tests. RESULTS: In PrEP patients, the median age was 35 years (range 25-40) and 83% (19/23) were white. The control patients were demographically similar (median age: 32 years [range 23-40]; 70% [16/23] white). Duodenal apoptosis in villous surface epithelium was increased in PrEP patients, with 14/23 (60.9%) patients having ≥10 surface apoptoses compared to 2/23 (8.7%) controls (P = 2.1 × 10-3 ) and 14/23 (61%) having clusters compared to 3/23 (13%) controls (P = 2.0 × 10-3 ). There was no significant association between increased surface apoptosis or clusters and clinical symptoms or duration of PrEP use. CONCLUSION: Markedly increased villous surface apoptosis, particularly in clusters, is often seen in the duodenum of patients taking PrEP. Although the mechanism and significance are unknown, knowledge of this peculiar finding may prevent unnecessary additional testing.

GI Polyps and Polyposis in Individuals Harboring Germline CHEK2 Mutations.

BACKGROUND: Checkpoint kinase 2 is a tumor suppressor gene in the DNA damage checkpoint system that may be mutated in several cancers. Patients with germline checkpoint kinase 2 mutations and multiple colon polyps were noted during routine care, and genetic testing is recommended for patients with as few as 10 lifetime polyps. OBJECTIVE: This study assessed whether checkpoint kinase 2 is associated with attenuated or oligopolyposis and characterized the GI clinicopathologic profile. DESIGN: Retrospective observational study. SETTINGS: Records from patients harboring germline checkpoint kinase 2 mutations from 1999 to 2020 were reviewed. PATIENTS: A total of 45 patients with germline checkpoint kinase 2 mutations with endoscopic examinations. MAIN OUTCOME MEASURES: Description of clinicopathologic variables. RESULTS: Twenty-five of 45 patients had polyps: 3 with only upper GI polyps, 17 with only lower GI polyps, and 5 with both upper and lower GI polyps. The most common germline checkpoint kinase 2 mutations in patients with polyps were p.S428F (n = 10), p.I157T (n = 4), and p.T476M (n = 2), with other mutations present in 1 patient each. Among patients with lower GI polyps, 9 had adenomas, 6 had serrated polyps, 1 had an inflammatory polyp, and 6 had both adenomatous and serrated polyps. Three patients (p.I157T, n = 2; p.R117G, n = 1) had more than 10 adenomas and 1 (p.G259fs) had 18 serrated polyps. Five patients (11.1%) developed colorectal adenocarcinoma, including 2 with more than 10 adenomas. Five patients with p.S428F (50%) exclusively had right-sided adenomas. LIMITATIONS: Single-center descriptive study. CONCLUSIONS: Germline checkpoint kinase 2 mutations should be considered in patients with polyposis. The preponderance of right-sided adenomas in patients with p.S428F mutations suggests the importance of right-sided colonoscopy in these patients. See Video Abstract . PLIPOS Y POLIPOSIS GASTROINTESTINALES EN INDIVIDUOS QUE ALBERGAN MUTACIONES EN LA LNEA GERMINAL DEL GEN CHEK: ANTECEDENTES:El punto de control quinasa 2 (CHEK2) es un gen supresor de tumores en el sistema de puntos de control de daño del ácido desoxirribonucleico (ADN) que puede mutar en varios cánceres. Durante la atención de rutina se observaron pacientes con mutaciones de la línea germinal CHEK2 y múltiples pólipos en el colon, y se recomiendan pruebas genéticas para pacientes con al menos 10 pólipos en su vida.OBJETIVO:Este estudio evaluó si CHEK2 está asociado con poliposis atenuada u oligopoliposis y caracterizó el perfil clínico-patológico gastrointestinal (GI).DISEÑO:Estudio observacional retrospectivo.ESCENARIO:Se revisaron los registros de pacientes que albergaban mutaciones de la línea germinal CHEK2 de 1999 a 2020.PACIENTES:45 pacientes con mutaciones de la línea germinal CHEK2 con exámenes endoscópicos.PRINCIPALES MEDIDAS DE RESULTADO:Descripción de variables clínico-patológicas.RESULTADOS:25 de 45 pacientes tenían pólipos: 3 sólo con pólipos GI superiores, 17 sólo con pólipos GI inferiores y 5 con pólipos GI superiores e inferiores. Las mutaciones de la línea germinal CHEK2 más comunes en pacientes con pólipos fueron p.S428F (n = 10), p.I157T (n = 4) y p.T476M (n = 2), con otras mutaciones presentes en 1 paciente cada una. Entre los pacientes con pólipos gastrointestinales inferiores, 9 tenían adenomas, 6 tenían pólipos serrados, 1 tenía un pólipo inflamatorio y 6 tenían pólipos tanto adenomatosos como serrados. Tres pacientes (p.I157T, n=2; p.R117G, n = 1) tenían >10 adenomas y 1 (p.G259fs) tenía 18 pólipos serrados. Cinco pacientes (11,1%) desarrollaron adenocarcinoma colorrectal, incluidos 2 con >10 adenomas. Cinco pacientes con p.S428F (50%) tenían exclusivamente adenomas del lado derecho.LIMITACIONES:Estudio descriptivo unicéntrico.CONCLUSIONES:Las mutaciones de la línea germinal CHEK2 deben considerarse en pacientes con poliposis. La preponderancia de adenomas del lado derecho en pacientes con mutaciones p.S428F sugiere la importancia de la colonoscopia del lado derecho en estos pacientes. (Traducción-Dr. Felipe Bellolio ).

Glycogenic hepatopathy is associated with type 1 diabetes mellitus in only a minority of cases in a contemporary adult population.

OBJECTIVES: This study examines the clinical-pathological profiles of patients with glycogenic hepatopathy in a contemporary cohort of patients at an adult acute care hospital. METHODS: Liver biopsies with glycogenic hepatopathy were retrieved from the departmental surgical pathology database, the histological findings were studied, and the clinical findings were reviewed. RESULTS: Five cases of glycogenic hepatopathy were found, including cases associated with type 1 diabetes mellitus (n = 1), type 2 diabetes mellitus (n = 1), corticosteroids (n = 2), and anorexia (n = 2, including the patient with type 1 diabetes). AST and ALT were normal to mildly elevated (13-115 U/L and 7-126 U/L, respectively). Trace ascites was present in two patients. Hepatomegaly was only present in the patient with type 1 diabetes at the time of diagnosis. CONCLUSIONS: Four of five cases were associated with etiologies other than type 1 diabetes, which is widely reported as the most common etiology of glycogenic hepatopathy. This study suggests that etiologies currently only rarely recognized may actually be more common causes of glycogenic hepatopathy than type 1 diabetes in a contemporary adult population. It is important not only to recognize that these rarely reported causes of glycogenic hepatopathy may be underrecognized, but that the clinical presentation may also be mild.

Cell polarity (the 'four lines') distinguishes gastric dysplasia from epithelial changes in reactive gastropathy.

AIMS: Gastric dysplasia is a risk factor for synchronous and subsequent gastric carcinoma. Distinguishing gastric dysplasia from reactive changes is subject to interobserver disagreement and is a frequent reason for expert consultation. We previously used assessment of surface cell polarity (the 'four lines') as a key feature to decrease equivocal diagnoses in Barrett oesophagus. In the current study, we examined for the presence or absence of the four lines in gastric dysplasia and reactive gastropathy. MATERIALS AND METHODS: The study includes all (n = 91) in-house biopsies with at least gastric dysplasia from the surgical pathology archives of two academic institutions during a 5-year period from 2008 to 2012. A reactive gastropathy group (n = 60) was created for comparison. RESULTS: The dysplasia/neoplasia group was comprised of 14 biopsies of gastric foveolar-type dysplasia, 59 of intestinal-type dysplasia, 14 with dysplasia in fundic gland polyps, three pyloric gland adenomas and one oxyntic gland adenoma. Loss of surface cell polarity was seen in all 88 dysplasia cases with evaluable surface epithelium. All 57 reactive gastropathy cases with evaluable surface epithelium showed intact surface cell polarity except in focal areas directly adjacent to erosions in 17 cases, where the thin wisp of residual surface mucin could not be appreciated on haematoxylin and eosin. CONCLUSION: Surface cell polarity (the four lines) was lost in all gastric dysplasia biopsies with evaluable surface epithelium and maintained in all biopsies of reactive gastropathy. Caution should be taken in using this feature adjacent to erosions in reactive gastropathy.

Lymphogranuloma venereum (LGV) of the anorectum: evaluation of clinicopathological associations and the utility of a novel RNA in-situ hybridisation stain.

AIMS: Recent studies from multiple global regions have reported a resurgence of lymphogranuloma venereum (LGV) proctitis, which is caused by Chlamydia trachomatis (CT). LGV proctitis is histologically indistinguishable from other forms of sexually transmitted proctitis and is difficult to differentiate from inflammatory bowel disease. While immunohistochemical stains are available for syphilis, there is no commonly available stain for the tissue identification of CT. MATERIALS AND METHODS: From 200 positive CT nucleic acid tests (NAT) from anorectal swabs, we identified 12 patients with biopsies collected from the distal colorectum or anus within 90 days of the positive NAT. We collected basic demographic information and tabulated clinical and histological findings. We examined the performance of a novel RNA in-situ hybridisation (ISH) stain targeting CT 23s rRNA on these 12 cases and 10 controls from the anorectum. RESULTS: All 12 patients were male; nine were HIV+, two had concurrent gonococcal infection, one had concurrent syphilis and one had cytomegalovirus co-infection. The majority of biopsies (11 of 12) showed mild or moderate acute inflammation, had a prominent lymphoplasmacytic infiltrate (eight of 11) and lacked marked crypt distortion (10 of 10). The RNA ISH stain was positive in 10 of 12 cases (sensitivity 83%). One case showed equivocal staining. No controls showed definitive positive staining (specificity 100%). One had equivocal staining. CONCLUSION: Our series showed that anorectal LGV had similar histological findings to those of prior STI proctitis series predominantly comprised of syphilis. The novel RNA ISH stain was sensitive and specific and may show utility in differentiating types of STI proctitis.

Master transcription factors form interconnected circuitry and orchestrate transcriptional networks in oesophageal adenocarcinoma.

OBJECTIVE: While oesophageal squamous cell carcinoma remains infrequent in Western populations, the incidence of oesophageal adenocarcinoma (EAC) has increased sixfold to eightfold over the past four decades. We aimed to characterise oesophageal cancer-specific and subtypes-specific gene regulation patterns and their upstream transcription factors (TFs). DESIGN: To identify regulatory elements, we profiled fresh-frozen oesophageal normal samples, tumours and cell lines with chromatin immunoprecipitation sequencing (ChIP-Seq). Mathematical modelling was performed to establish (super)-enhancers landscapes and interconnected transcriptional circuitry formed by master TFs. Coregulation and cooperation between master TFs were investigated by ChIP-Seq, circularised chromosome conformation capture sequencing and luciferase assay. Biological functions of candidate factors were evaluated both in vitro and in vivo. RESULTS: We found widespread and pervasive alterations of the (super)-enhancer reservoir in both subtypes of oesophageal cancer, leading to transcriptional activation of a myriad of novel oncogenes and signalling pathways, some of which may be exploited pharmacologically (eg, leukemia inhibitory factor (LIF) pathway). Focusing on EAC, we bioinformatically reconstructed and functionally validated an interconnected circuitry formed by four master TFs-ELF3, KLF5, GATA6 and EHF-which promoted each other's expression by interacting with each super-enhancer. Downstream, these master TFs occupied almost all EAC super-enhancers and cooperatively orchestrated EAC transcriptome. Each TF within the transcriptional circuitry was highly and specifically expressed in EAC and functionally promoted EAC cell proliferation and survival. CONCLUSIONS: By establishing cancer-specific and subtype-specific features of the EAC epigenome, our findings promise to transform understanding of the transcriptional dysregulation and addiction of EAC, while providing molecular clues to develop novel therapeutic modalities against this malignancy.

Solvent detergent treated pooled plasma and reduction of allergic transfusion reactions.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) patients have increased risk for allergic transfusion reactions (ATR) due to the number of plasma products they require. This study evaluated the efficacy of solvent detergent treated plasma (S/D treated plasma) to reduce ATRs. STUDY DESIGN AND METHODS: All TTP patients who presented from April 2014 to February 2015 and experienced a moderate-severe ATR to untreated plasma with TPE were switched to S/D treated plasma (Octaplas) for their remaining procedures and included in the study. Patient records were retrospectively reviewed. RESULTS: The overall ATR rate per procedure decreased from 35.0% (95% CI = 15.4%-59.2%) with untreated plasma to 1.4% ([1/73] 95% CI = 0.0%-7.4%) with S/D treated plasma. The moderate-severe ATR rate decreased from 20.0% ([4/20] 95% CI = 5.7%-43.7%) with untreated plasma to 0.0% ([0/73] 95% CI = 0.0%-4.9%) with S/D treated plasma. The overall ATR rate per plasma unit decreased from 2.6% (95%CI = 1.0%-5.1%) with untreated plasma to 0.1% (95% CI = 0.0%-0.4%) with S/D treated plasma. No patients experienced VTE while receiving untreated plasma. Four patients experienced VTE events while receiving S/D treated plasma. All patients who experienced a VTE had additional risk factors for VTE. CONCLUSION: S/D plasma has promise as an effective product to reduce the risk of ATRs in TTP patients. Given the high risk of ATR in TTP patients, consideration of S/D plasma instead of untreated plasma for TPE in these patients may be warranted, especially for patients with a history of moderate to severe ATR. More extensive studies are needed to confirm these findings.

Single-cell sequencing defines genetic heterogeneity in pancreatic cancer precursor lesions.

Intraductal papillary mucinous neoplasms (IPMNs) are precursors to pancreatic cancer; however, little is known about genetic heterogeneity in these lesions. The objective of this study was to characterize genetic heterogeneity in IPMNs at the single-cell level. We isolated single cells from fresh tissue from ten IPMNs, followed by whole genome amplification and targeted next-generation sequencing of pancreatic driver genes. We then determined single-cell genotypes using a novel multi-sample mutation calling algorithm. Our analyses revealed that different mutations in the same driver gene frequently occur in the same IPMN. Two IPMNs had multiple mutations in the initiating driver gene KRAS that occurred in unique tumor clones, suggesting the possibility of polyclonal origin or an unidentified initiating event preceding this critical mutation. Multiple mutations in later-occurring driver genes were also common and were frequently localized to unique tumor clones, raising the possibility of convergent evolution of these genetic events in pancreatic tumorigenesis. Single-cell sequencing of IPMNs demonstrated genetic heterogeneity with respect to early and late occurring driver gene mutations, suggesting a more complex pattern of tumor evolution than previously appreciated in these lesions. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Is a Pathological Complete Response Following Neoadjuvant Chemoradiation Associated With Prolonged Survival in Patients With Pancreatic Cancer?

OBJECTIVES: To describe the survival outcome of patients with borderline resectable or locally advanced pancreatic ductal adenocarcinoma (BR/LA-PDAC) who have a pathologic complete response (pCR) following neoadjuvant chemoradiation. BACKGROUND: Patients with BR/LA-PDAC are often treated with neoadjuvant chemoradiation in an attempt to downstage the tumor. Uncommonly, a pCR may result. METHODS: A retrospective review of a prospectively maintained database was performed at a single institution. pCR was defined as no viable tumor identified in the pancreas or lymph nodes by pathology. A near complete response (nCR) was defined as a primary tumor less than 1 cm, without nodal metastasis. Overall survival (OS) and disease-free survival (DFS) were reported. RESULTS: One hundred eighty-six patients with BR/LA-PDAC underwent neoadjuvant chemoradiation and subsequent pancreatectomy. Nineteen patients (10%) had a pCR, 29 (16%) had an nCR, and the remaining 138 (74%) had a limited response. Median DFS was 26 months in patients with pCR, which was superior to nCR (12 months, P = 0.019) and limited response (12 months, P < 0.001). The median OS of nCR (27 months, P = 0.003) or limited response (26 months, P = 0.001) was less than that of pCR (more than 60 months). In multivariable analyses pCR was an independent prognostic factor for DFS (HR = 0.45; 0.22-0.93, P = 0.030) and OS (HR=0.41; 0.17-0.97, P = 0.044). Neoadjuvant FOLFIRINOX (HR=0.47; 0.26-0.87, P = 0.015) and negative lymph node status (HR=0.57; 0.36-0.90, P = 0.018) were also associated with improved survival. CONCLUSIONS: Patients with BR/LA-PDAC who had a pCR after neoadjuvant chemoradiation had a significantly prolonged survival compared with those who had nCR or a limited response.

Dynamics of self-assembled cytosine nucleobases on graphene.

Molecular self-assembly of cytosine (C n ) bases on graphene was investigated using molecular dynamics methods. For free-standing C n bases, simulation conditions (gas versus aqueous) determine the nature of self-assembly; the bases prefer to aggregate in the gas phase and are stabilized by intermolecular H-bonds, while in the aqueous phase, the water molecules disrupt base-base interactions, which facilitate the formation of π-stacked domains. The substrate-induced effects, on the other hand, find the polarity and donor-acceptor sites of the bases to govern the assembly process. For example, in the gas phase, the assembly of C n bases on graphene displays short-range ordered linear arrays stabilized by the intermolecular H-bonds. In the aqueous phase, however, there are two distinct configurations for the C n bases assembly on graphene. For the first case corresponding to low surface coverage, the bases are dispersed on graphene and are isolated. The second configuration archetype is disordered linear arrays assembled with medium and high surface coverage. The simulation results establish the role of H-bonding, vdW π-stacking, and the influence of graphene surface towards the self-assembly. The ability to regulate the assembly into well-defined patterns can aid in the design of self-assembled nanostructures for the next-generation DNA based biosensors and nanoelectronic devices.

Some observations on Barrett esophagus and associated dysplasia.

Biopsy samples from esophageal columnar metaplasia and dysplasia are commonly encountered in Western pathology practice and knowing a few pitfalls can save both pathologists and patients a great deal of anxiety. Herein we discuss criteria for Barrett esophagus, evaluation of dysplasia, and some pitfalls in reviewing endoscopic mucosal resections. Also included is a summary of suggested follow-up for patients with Barrett esophagus.

Squamous cell carcinoma complicating a chronic lesion of hidradenitis suppurativa: a case report and review of the literature.

Squamous cell carcinoma (SCC) arising from chronic hidradenitis suppurativa (HS) is rare; however, the morbidity associated with this presentation is high and management has not been standardised or optimised. We present a case of HS of the perineum and buttocks complicated by SCC, requiring multiple extensive surgical resections. Adjuvant radiotherapy was withheld initially because of concern for poor healing of the surgical wound but was eventually initiated after a second recurrence was identified. The patient ultimately expired 4 years after the initial diagnosis of SCC. We also review 80 cases of SCC complicating HS found in the English literature. Case reports and mechanistic studies suggest the possibility that human papilloma virus and smoking may be risk factors associated with SCC in HS. Despite the majority of SCC cases being well-differentiated tumours in HS, the highly aggressive nature of SCC in HS and its high likelihood for rapid progression, recurrence, metastasis and high mortality suggests the need to advocate for aggressive treatment. We recommend an aggressive approach to management at the time of SCC diagnosis in HS, which includes appropriate imaging to establish the extent of the tumour, large and deep surgical excision, sentinel lymph node evaluation, consultation with radiation oncology for potential adjuvant radiation therapy and close surveillance.

A robust nonlinear tissue-component discrimination method for computational pathology.

Advances in digital pathology, specifically imaging instrumentation and data management, have allowed for the development of computational pathology tools with the potential for better, faster, and cheaper diagnosis, prognosis, and prediction of disease. Images of tissue sections frequently vary in color appearance across research laboratories and medical facilities because of differences in tissue fixation, staining protocols, and imaging instrumentation, leading to difficulty in the development of robust computational tools. To address this challenge, we propose a novel nonlinear tissue-component discrimination (NLTD) method to register automatically the color space of histopathology images and visualize individual tissue components, independent of color differences between images. Our results show that the NLTD method could effectively discriminate different tissue components from different types of tissues prepared at different institutions. Further, we demonstrate that NLTD can improve the accuracy of nuclear detection and segmentation algorithms, compared with using conventional color deconvolution methods, and can quantitatively analyze immunohistochemistry images. Together, the NLTD method is objective, robust, and effective, and can be easily implemented in the emerging field of computational pathology.

Informed conditioning on clinical covariates increases power in case-control association studies.

Genetic case-control association studies often include data on clinical covariates, such as body mass index (BMI), smoking status, or age, that may modify the underlying genetic risk of case or control samples. For example, in type 2 diabetes, odds ratios for established variants estimated from low-BMI cases are larger than those estimated from high-BMI cases. An unanswered question is how to use this information to maximize statistical power in case-control studies that ascertain individuals on the basis of phenotype (case-control ascertainment) or phenotype and clinical covariates (case-control-covariate ascertainment). While current approaches improve power in studies with random ascertainment, they often lose power under case-control ascertainment and fail to capture available power increases under case-control-covariate ascertainment. We show that an informed conditioning approach, based on the liability threshold model with parameters informed by external epidemiological information, fully accounts for disease prevalence and non-random ascertainment of phenotype as well as covariates and provides a substantial increase in power while maintaining a properly controlled false-positive rate. Our method outperforms standard case-control association tests with or without covariates, tests of gene x covariate interaction, and previously proposed tests for dealing with covariates in ascertained data, with especially large improvements in the case of case-control-covariate ascertainment. We investigate empirical case-control studies of type 2 diabetes, prostate cancer, lung cancer, breast cancer, rheumatoid arthritis, age-related macular degeneration, and end-stage kidney disease over a total of 89,726 samples. In these datasets, informed conditioning outperforms logistic regression for 115 of the 157 known associated variants investigated (P-value = 1 × 10(-9)). The improvement varied across diseases with a 16% median increase in χ(2) test statistics and a commensurate increase in power. This suggests that applying our method to existing and future association studies of these diseases may identify novel disease loci.

Characterizing genetic risk at known prostate cancer susceptibility loci in African Americans.

GWAS of prostate cancer have been remarkably successful in revealing common genetic variants and novel biological pathways that are linked with its etiology. A more complete understanding of inherited susceptibility to prostate cancer in the general population will come from continuing such discovery efforts and from testing known risk alleles in diverse racial and ethnic groups. In this large study of prostate cancer in African American men (3,425 prostate cancer cases and 3,290 controls), we tested 49 risk variants located in 28 genomic regions identified through GWAS in men of European and Asian descent, and we replicated associations (at p≤0.05) with roughly half of these markers. Through fine-mapping, we identified nearby markers in many regions that better define associations in African Americans. At 8q24, we found 9 variants (p≤6×10(-4)) that best capture risk of prostate cancer in African Americans, many of which are more common in men of African than European descent. The markers found to be associated with risk at each locus improved risk modeling in African Americans (per allele OR = 1.17) over the alleles reported in the original GWAS (OR = 1.08). In summary, in this detailed analysis of the prostate cancer risk loci reported from GWAS, we have validated and improved upon markers of risk in some regions that better define the association with prostate cancer in African Americans. Our findings with variants at 8q24 also reinforce the importance of this region as a major risk locus for prostate cancer in men of African ancestry.

5-Hydroxymethylcytosine (5-hmC) loss is a marker of malignancy in biliary neoplasms.

OBJECTIVES: Adenocarcinomas of the biliary tract frequently present diagnostic challenges because of their histologic overlap with benign and preinvasive lesions. The molecular profiles of biliary adenocarcinomas vary by anatomical location. Variations in IDH1/2, common in intrahepatic cholangiocarcinoma, can lead to defective production of 5-hydroxymethylcytosine (5-hmC). Limited ancillary studies are available for biliary adenocarcinomas, and loss of 5-hmC staining could serve as a helpful ancillary diagnostic tool for biliary tract malignancies. METHODS: We evaluated 93 cases-20 benign biliary lesions, 15 preinvasive biliary neoplasms, 46 invasive biliary carcinomas, and 12 pancreatic adenocarcinomas-for 5-hmC staining. Preoperative biopsies from 16 cases of biliary carcinoma were also stained. Sixteen nonneoplastic/reactive bile duct biopsies served as controls. RESULTS: Loss of 5-hmC was seen in 41 of 46 (89.1%) biliary malignancies vs 0 of 20 benign tumors (P < .001), for a sensitivity and specificity of 89.1% and 100%, respectively. Intrahepatic cholangiocarcinoma showed loss of 5-hmC in 11 of 13 (84.6%) cases, similar to the 30 of 33 (90.9%) cases in other biliary adenocarcinomas (P = .61). Similarly, 5-hmC loss was more frequent in distal bile duct adenocarcinomas than in pancreatic ductal adenocarcinomas, at 15 of 17 (88.2%) vs 4 of 12 (33.3%), respectively (P = .0045). There was no difference in the frequency of 5-hmC loss in patients that received neoadjuvant therapy vs those who did not (90.9% vs 88.6%, P > .99). 5-hmC immunohistochemistry in preoperative biopsies was concordant with the resection specimen in 81.3% (13/16) of cases. CONCLUSIONS: Loss of 5-hmC is not unique to intrahepatic cholangiocarcinoma among biliary carcinomas, but is a useful diagnostic marker differentiating malignancies of the biliary tree from benign mimics.

Analysis of case-control association studies with known risk variants.

MOTIVATION: The question of how to best use information from known associated variants when conducting disease association studies has yet to be answered. Some studies compute a marginal P-value for each Several Nucleotide Polymorphisms independently, ignoring previously discovered variants. Other studies include known variants as covariates in logistic regression, but a weakness of this standard conditioning strategy is that it does not account for disease prevalence and non-random ascertainment, which can induce a correlation structure between candidate variants and known associated variants even if the variants lie on different chromosomes. Here, we propose a new conditioning approach, which is based in part on the classical technique of liability threshold modeling. Roughly, this method estimates model parameters for each known variant while accounting for the published disease prevalence from the epidemiological literature. RESULTS: We show via simulation and application to empirical datasets that our approach outperforms both the no conditioning strategy and the standard conditioning strategy, with a properly controlled false-positive rate. Furthermore, in multiple data sets involving diseases of low prevalence, standard conditioning produces a severe drop in test statistics whereas our approach generally performs as well or better than no conditioning. Our approach may substantially improve disease gene discovery for diseases with many known risk variants. AVAILABILITY: LTSOFT software is available online http://www.hsph.harvard.edu/faculty/alkes-price/software/.