Thomas L. Vaughan

Increased risk of noncardia gastric cancer associated with proinflammatory cytokine gene polymorphisms

BACKGROUND & AIMS Genetic variations in proinflammatory and anti-inflammatory cytokine genes influence individual response to carcinogenic exposures. Polymorphisms in interleukin (IL)-1 beta and its endogenous receptor antagonist are associated with risk of Helicobacter pylori-related gastric cancer. The aim of this study was to evaluate the role of proinflammatory cytokine gene polymorphisms in gastric and esophageal cancers defined by anatomic subsite. METHODS We assessed polymorphisms of the IL-1 gene cluster and 4 other cytokine genes in a population-based case-control study of upper gastrointestinal cancers, including gastric cardia (n = 126) and noncardia adenocarcinoma (n = 188), esophageal squamous cell carcinoma (n = 53), and adenocarcinoma (n = 108), and frequency-matched controls (n = 212). ORs for the different cancers were computed from logistic regression models adjusted for potential confounding factors. RESULTS Proinflammatory genotypes of tumor necrosis factor alpha and IL-10 were each associated with more than doubling of the risk of noncardia gastric cancer. Carriage of multiple proinflammatory polymorphisms of IL-1B(o) IL-1 receptor antagonist, tumor necrosis factor A, and IL-10 conferred greater risk, with ORs (and 95% confidence intervals) of 2.8 (1.6-5.1) for one, 5.4 (2.7-10.6) for 2, and 27.3 (7.4-99.8) for 3 or 4 high-risk genotypes. In contrast, these polymorphisms were not consistently related to the risks of esophageal or gastric cardia cancers. Polymorphisms in IL-4 and IL-6 were not associated with any of the cancers studied. CONCLUSIONS A proinflammatory cytokine genetic profile increases the risk of noncardia gastric adenocarcinoma but not other upper gastrointestinal cancers, possibly by inducing a hypochlorhydric and atrophic response to gastric H. pylori infection.

Occupational exposure assessment in case-control studies: opportunities for improvement

Community based case–control studies are an efficient means to study disease aetiologies, and may be the only practical means to investigate rare diseases. However, exposure assessment remains problematic. We review the literature on the validity and reliability of common case–control exposure assessment methods: occupational histories, job–exposure matrices (JEMs), self reported exposures, and expert assessments. Given the variable quality of current exposure assessment techniques, we suggest methods to improve assessments, including the incorporation of hygiene measurements: using data from administrative exposure databases; using results of studies identifying determinants of exposure to develop questionnaires; and where reasonable given latency and biological half life considerations, directly measuring exposures of study subjects.

Barrett's oesophagus and oesophageal adenocarcinoma: time for a new synthesis.

The public health importance of Barretts oesophagus lies in its association with oesophageal adenocarcinoma. The incidence of oesophageal adenocarcinoma has risen at an alarming rate over the past four decades in many regions of the Western world, and there are indications that the incidence of this disease is on the rise in Asian populations in which it has been rare. Much has been learned of host and environmental risk factors that affect the incidence of oesophageal adenocarcinoma, and data indicate that patients with Barretts oesophagus rarely develop oesophageal adenocarcinoma. Given that 95% of oesophageal adenocarcinomas arise in individuals without a prior diagnosis of Barretts oesophagus, what strategies can be used to reduce late diagnosis of oesophageal adenocarcinoma?

Effect of Segment Length on Risk for Neoplastic Progression in Patients with Barrett Esophagus

In Barrett esophagus, the normal stratified squamous epithelium of the esophagus is replaced by specialized columnar epithelium in response to the tissue injury caused by chronic gastroesophageal reflux (1). Barrett esophagus is present in approximately 5% to 15% of persons with clinical indications for elective upper endoscopy (2-5). The results of several recent studies suggest that most patients with Barrett esophagus have short-segment (<3 cm) Barrett esophagus (2-7). Patients with long-segment ( 3 cm) Barrett esophagus are known to have a much greater risk for esophageal adenocarcinoma than members of the general population (8-11). Because investigators were initially uncertain whether short-segment Barrett esophagus predisposed persons to esophageal adenocarcinoma and because short-segment Barrett esophagus is more difficult to diagnose endoscopically (12), patients with short segments were often excluded from studies of the natural history of Barrett esophagus (8-11, 13, 14). Since the late 1980s, however, there have been several reports of esophageal adenocarcinoma in patients with short-segment Barrett esophagus (5, 15-18). Although this suggests that patients with short-segment Barrett esophagus are at increased risk for esophageal adenocarcinoma, the extent of the increase is largely unknown. The survival of patients who receive a diagnosis of esophageal adenocarcinoma is usually poor. More than 90% of patients with invasive disease die within 5 years of diagnosis (19). If tumors are resected at an early stage, however, survival improves substantially (20-22). Therefore, many authors have recommended regular endoscopic surveillance for patients with Barrett esophagus who are good surgical candidates (20, 21, 23-27) and prompt resection of the entire Barrett segment if cancer is identified (22, 28, 29). However, endoscopic surveillance has several disadvantages, including its high cost, procedure-related risks, inconvenience, and discomfort (30, 31). Because only a small percentage of patients with Barrett esophagus will develop cancer, it is reasonable to question the merits of frequent endoscopic surveillance for all such persons (11, 12, 23). We hypothesized that the risk for esophageal adenocarcinoma would increase with Barrett segment length. If this was true, it might be appropriate to perform endoscopic surveillance less frequently in patients with short-segment Barrett esophagus than in those with longer segments. To investigate this hypothesis, we conducted a prospective cohort study among patients who were participating in the Seattle Barretts Esophagus Project, which includes regular endoscopic surveillance. We determined the incidence of esophageal adenocarcinoma in patients with short-segment Barrett esophagus and examined the relation between segment length and cancer risk through multivariate analyses. We also examined the relation between segment length and aneuploidy, a genetic abnormality that usually precedes the development of esophageal adenocarcinoma and has been shown to predict progression to cancer (32). Aneuploidy was chosen as an outcome of interest primarily because it occurred more frequently than cancer in the study cohort, thus increasing statistical power for analyzing the relation between segment length and neoplastic progression. Methods Study Sample Study participants were selected from a cohort of patients who were enrolled in the Seattle Barretts Esophagus Project and underwent endoscopic surveillance between July 1983 and July 1998. Gastroenterologists who practice in Washington State have been the primary source of referrals to this cohort. All cohort members who met the following criteria as of 10 July 1998 were included in our study: 1) at least two endoscopies with histologic diagnoses, 2) presence of specialized columnar epithelium in the esophagus at the first endoscopy, 3) a record of Barrett segment length at the first endoscopy, 4) no esophageal cancer at the first endoscopy, and 5) no history of esophageal cancer. Three hundred nine persons qualified for the study. All of the study patients received counseling on lifestyle measures to reduce gastroesophageal reflux, and most used acid-reducing medication regularly. The Human Subjects Review Committee at the University of Washington approved the study. To evaluate the relation between segment length and aneuploidy, it was necessary to have information about the presence or absence of aneuploidy from at least two endoscopies. Of the 208 patients for whom this information was available, 37 had aneuploidy at the first qualifying endoscopy and were therefore excluded, leaving 171 for analyses with the aneuploidy end point. Endoscopy Barrett segment length was defined as the distance between the esophagogastric junction and the squamocolumnar junction. The esophagogastric junction was defined as the endoscopic lower esophageal sphincter or, if this was not apparent, the location at which the tubular esophagus joined the proximal margin of the gastric folds. The squamocolumnar junction was defined as the location at which the light-pink mucosa of the squamous-lined esophagus joined the red mucosa of the columnar-lined esophagus. The locations of these landmarks were determined as the endoscope was withdrawn from the stomach to the upper esophagus. Air was always removed from the stomach before this assessment. Tissue samples were obtained by using the turn and suction technique and jumbo biopsy forceps, as described elsewhere (33, 34). Until 1992, four biopsies (one per quadrant of the esophagus) were obtained from every other centimeter of the Barrett segment in all patients. From 1992 through 1998, four biopsies (one per quadrant of the esophagus) were obtained from every centimeter of the Barrett segment in patients with a history of high-grade dysplasia. In all patients, at least one control biopsy specimen was also taken from the gastric fundus and several biopsy specimens were taken from any visible mucosal abnormality. Each biopsy specimen was oriented on plastic mesh, epithelial surface upward, as soon as it was obtained. The gastric biopsy specimen and half of the first biopsy specimen from every level were placed in separate vials containing minimum essential medium with 5% serum and 10% dimethyl sulfoxide. The specimens were then immediately placed on wet ice and were stored at 70 C for subsequent flow cytometric analysis. The other half of the first biopsy specimen and the remaining three biopsy specimens from each level were placed in Hollande solution (one vial per level) for subsequent histologic examination. The most advanced histologic diagnosis at a given endoscopy was used to select the follow-up interval to the next endoscopy and the biopsy protocol for that endoscopy. The median interval between endoscopies was 25 months for patients with a baseline diagnosis of metaplasia, 18 months for patients with a baseline diagnosis of indefinite for dysplasia or low-grade dysplasia, and 5 months for patients with a baseline diagnosis of high-grade dysplasia. Histologic Examination The fixed biopsy specimens were serially cut into 4-m sections, mounted onto slides, and stained with hematoxylin and eosin alone or with hematoxylin and eosin, saffron, and Alcian blue at a pH of 2.5. The slides were examined by an experienced gastrointestinal pathologist, as described elsewhere (35). A histologic diagnosis of negative for dysplasia, indefinite for dysplasia, low-grade dysplasia, high-grade dysplasia, or intramucosal carcinoma was assigned to each slide by using established criteria (36). Because pathologists cannot consistently differentiate between the diagnoses of indefinite for dysplasia and low-grade dysplasia (36), these histologic diagnoses were combined into one category for all statistical analyses. DNA Content Flow Cytometry The methods used to prepare biopsy specimens for cell sorting, to perform flow cytometry, and to analyze the resulting data have been described elsewhere (34). Aneuploidy was diagnosed if, in at least one biopsy specimen from a particular endoscopy, two discrete peaks were observed on the histogram (one reflecting the presence of an aneuploid population and the other reflecting the presence of a diploid population) and the aneuploid peak represented at least 2.5% of the cells in the biopsy specimen (32). Tetraploid DNA contents in the range of 3.85N to 4.1N were also excluded. Demographic, Lifestyle, and Anthropometric Data Trained staff used a standard questionnaire to interview 71% (220 of 309) of the patients in this study in person between January 1995 and July 1998. Collected data included information on cigarette use, usual weight, height, ethnicity, annual income, education, and symptoms of gastroesophageal reflux. Information on age at study entry and sex was extracted from electronic patient records. Statistical Analysis Incidence rates were calculated by dividing the total number of cases by the total follow-up time (in person-years) in the full study sample or in defined subsets of the study sample. For each patient, follow-up time within the cohort began on the date of the first endoscopy that met the eligibility criteria. In analyses in which cancer was the outcome of interest, follow-up time ended on the date of the last endoscopy before the end of our study (10 July 1998) or on the date of the endoscopy that led to a diagnosis of cancer, whichever occurred first. Similarly, in analyses in which aneuploidy was the outcome of interest, follow-up time ended on the date of the last endoscopy before the end of the study or on the date of the endoscopy that led to a diagnosis of aneuploidy. In the analyses in which aneuploidy was the disease end point, a small number of participants (n=10) received a diagnosis of cancer at an endoscopy for which no flow cytometry data were available. Because approximately 90% of esophageal adenocarcinomas contain aneuploid cell p

NSAIDs Modulate CDKN2A, TP53, and DNA Content Risk for Progression to Esophageal Adenocarcinoma

Background Somatic genetic CDKN2A, TP53, and DNA content abnormalities are common in many human cancers and their precursors, including esophageal adenocarcinoma (EA) and Barretts esophagus (BE), conditions for which aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) have been proposed as possible chemopreventive agents; however, little is known about the ability of a biomarker panel to predict progression to cancer nor how NSAID use may modulate progression. We aimed to evaluate somatic genetic abnormalities with NSAIDs as predictors of EA in a prospective cohort study of patients with BE. Methods and Findings Esophageal biopsies from 243 patients with BE were evaluated at baseline for TP53 and CDKN2A (p16) alterations, tetraploidy, and aneuploidy using sequencing; loss of heterozygosity (LOH); methylation-specific PCR; and flow cytometry. At 10 y, all abnormalities, except CDKN2A mutation and methylation, contributed to EA risk significantly by univariate analysis, ranging from 17p LOH (relative risk [RR] = 10.6; 95% confidence interval [CI] 5.2–21.3, p < 0.001) to 9p LOH (RR = 2.6; 95% CI 1.1–6.0, p = 0.03). A panel of abnormalities including 17p LOH, DNA content tetraploidy and aneuploidy, and 9p LOH was the best predictor of EA (RR = 38.7; 95% CI 10.8–138.5, p < 0.001). Patients with no baseline abnormality had a 12% 10-y cumulative EA incidence, whereas patients with 17p LOH, DNA content abnormalities, and 9p LOH had at least a 79.1% 10-y EA incidence. In patients with zero, one, two, or three baseline panel abnormalities, there was a significant trend toward EA risk reduction among NSAID users compared to nonusers (p = 0.01). The strongest protective effect was seen in participants with multiple genetic abnormalities, with NSAID nonusers having an observed 10-y EA risk of 79%, compared to 30% for NSAID users (p < 0.001). Conclusions A combination of 17p LOH, 9p LOH, and DNA content abnormalities provided better EA risk prediction than any single TP53, CDKN2A, or DNA content lesion alone. NSAIDs are associated with reduced EA risk, especially in patients with multiple high-risk molecular abnormalities.

Gastroesophageal reflux disease, use of H2 receptor antagonists, and risk of esophageal and gastric cancer

AbstractObjective: The incidence of esophageal adenocarcinoma has risen rapidly in the past two decades, for unknown reasons. The goal of this analysis was to determine whether gastroesophageal reflux disease (GERD) or the medications used to treat it are associated with an increased risk of esophageal or gastric cancer, using data from a large population-based case–control study. Methods: Cases were aged 30–79 years, newly diagnosed with esophageal adenocarcinoma (n = 293), esophageal squamous cell carcinoma (n = 221), gastric cardia adenocarcinoma (n = 261), or non-cardia gastric adenocarcinoma (n = 368) in three areas with population-based tumor registries. Controls (n = 695) were chosen by random digit dialing and from Health Care Financing Administration rosters. Data were collected using an in-person structured interview. Results: History of gastric ulcer was associated with an increased risk of non-cardia gastric adenocarcinoma (OR 2.1, 95% CI 1.4–3.2). Risk of esophageal adenocarcinoma increased with frequency of GERD symptoms; the odds ratio in those reporting daily symptoms was 5.5 (95% CI 3.2–9.3). Ever having used H2 blockers was unassociated with esophageal adenocarcinoma risk (OR 0.9, 95% CI 0.5–1.5). The odds ratio was 1.3 (95% CI 0.6–2.8) in long-term (4 or more years) users, but increased to 2.1 (95% CI 0.8–5.6) when use in the 5 years prior to the interview was disregarded. Risk was also modestly increased among users of antacids. Neither GERD symptoms nor use of H2 blockers or antacids was associated with risk of the other three tumor types. Conclusions: Individuals with long-standing GERD are at increased risk of esophageal adenocarcinoma, whether or not the symptoms are treated with H2blockers or antacids.

Non-steroidal anti-inflammatory drugs and risk of neoplastic progression in Barrett's oesophagus: a prospective study

BACKGROUND Aspirin and other non-steroidal anti-inflammatory drugs (NSAID) probably decrease the risk of colorectal neoplasia; however their effect on development of oesophageal adenocarcinoma is less clear. We aimed to assess the role of NSAID in the development of oesophageal adenocarcinoma and precursor lesions in people with Barretts oesophagus--a metaplastic disorder that confers a high risk of oesophageal adenocarcinoma. METHODS We did a prospective study of the relation between duration, frequency, and recency of NSAID use and the risk of oesophageal adenocarcinoma, aneuploidy, and tetraploidy in a cohort of 350 people with Barretts oesophagus followed for 20,770 person-months. We used proportional-hazards regression to calculate hazard ratios (HR) adjusted for age, sex, cigarette use, and anthropometric measurements. FINDINGS Median follow-up was 65.5 months (range 3.1-106.9). Compared with never users, HR for oesophageal adenocarcinoma (n=37 cases) in current NSAID users was 0.32 (95% CI 0.14-0.76), and in former users was 0.70 (0.31-1.58). 5-year cumulative incidence of oesophageal adenocarcinoma was 14.3% (95% CI 9.3-21.6) for never users, 9.7% (4.5-20.5) for former users, and 6.6% (3.1-13.6) for current NSAID users. When changes in NSAID use during follow up were taken into account, the associations were strengthened: HR for oesophageal adenocarcinoma for current users at baseline or afterwards was 0.20 (95% CI 0.10-0.41) compared with never users. Compared with never users, current NSAID users (at baseline and follow-up) had less aneuploidy (n=35 cases; 0.25 [0.12-0.54]) and tetraploidy (n=45 cases; 0.44 [0.22-0.87]). INTERPRETATION NSAID use might be an effective chemopreventive strategy, reducing the risk of neoplastic progression in Barretts oesophagus.

Cigarette Smoking and Adenocarcinomas of the Esophagus and Esophagogastric Junction: A Pooled Analysis From the International BEACON Consortium

BACKGROUND Previous studies that showed an association between smoking and adenocarcinomas of the esophagus and esophagogastric junction were limited in their ability to assess differences by tumor site, sex, dose-response, and duration of cigarette smoking cessation. METHODS We used primary data from 10 population-based case-control studies and two cohort studies from the Barretts Esophagus and Esophageal Adenocarcinoma Consortium. Analyses were restricted to white non-Hispanic men and women. Patients were classified as having esophageal adenocarcinoma (n = 1540), esophagogastric junctional adenocarcinoma (n = 1450), or a combination of both (all adenocarcinoma; n = 2990). Control subjects (n = 9453) were population based. Associations between pack-years of cigarette smoking and risks of adenocarcinomas were assessed, as well as their potential modification by sex and duration of smoking cessation. Study-specific odds ratios (ORs) estimated using multivariable logistic regression models, adjusted for age, sex, body mass index, education, and gastroesophageal reflux, were pooled using a meta-analytic methodology to generate summary odds ratios. All statistical tests were two-sided. RESULTS The summary odds ratios demonstrated strong associations between cigarette smoking and esophageal adenocarcinoma (OR = 1.96, 95% confidence interval [CI] = 1.64 to 2.34), esophagogastric junctional adenocarcinoma (OR = 2.18, 95% CI = 1.84 to 2.58), and all adenocarcinoma (OR = 2.08, 95% CI = 1.83 to 2.37). In addition, there was a strong dose-response association between pack-years of cigarette smoking and each outcome (P < .001). Compared with current smokers, longer smoking cessation was associated with a decreased risk of all adenocarcinoma after adjusting for pack-years (<10 years of smoking cessation: OR = 0.82, 95% CI = 0.60 to 1.13; and > or =10 years of smoking cessation: OR = 0.71, 95% CI = 0.56 to 0.89). Sex-specific summary odds ratios were similar. CONCLUSIONS Cigarette smoking is associated with increased risks of adenocarcinomas of the esophagus and esophagogastric junction in white men and women; compared with current smoking, smoking cessation was associated with reduced risks.

Semen quality of men employed at a lead smelter.

OBJECTIVE: To evaluate the effects of recent and long term occupational lead exposure on indicators of male reproductive health. METHODS: In a cross sectional study of male employees of a lead smelter (n = 2469), blood samples were obtained from 152 workers including 119 who also provided semen samples. Semen analysis and serum concentrations of testosterone, follicle stimulating hormone, and luteinising hormone were used as indicators of reproductive health. Semen and hormone variables were examined in relation to measures of current and long term body lead burden estimated from current blood lead concentrations and historical blood lead monitoring data. RESULTS: For current blood lead concentration groups of < 15, 15-24, 25-39, > 40 micrograms/dl, the geometric mean sperm concentrations were, respectively, 79.1, 56.5, 62.7, and 44.4 million cells/ml and geometric mean total sperm counts were 186, 153, 137, and 89 million cells (P for trend 0.04). Compared with workers with blood lead concentrations less than 15 micrograms/dl, workers with current blood lead concentrations of 40 micrograms/dl or more had an increased risk of below normal sperm concentration (odds ratio (OR) 8.2, 95% confidence interval (95% CI) 1.2-57.9) and total sperm count (OR 2.6, 95% CI 0.4-15.7), based on World Health Organisation standards. Independent of current lead exposure, sperm concentration, total sperm count, and total motile sperm count were inversely related to measures of long term lead exposure. No association was found between lead exposure and measures of sperm motility, sperm morphology, or serum concentrations of reproductive hormones. CONCLUSIONS: Blood lead concentrations below the currently accepted worker protection criteria seem to adversely affect spermatogenesis.

Leukocyte telomere length predicts cancer risk in Barrett's esophagus.

Purpose: Leukocyte telomere length has gained attention as a marker of oxidative damage and age-related diseases, including cancer. We hypothesize that leukocyte telomere length might be able to predict future risk of cancer and examined this in a cohort of patients with Barretts esophagus, who are at increased risk of esophageal adenocarcinoma and thus were enrolled in a long-term cancer surveillance program. Patients and Methods: In this prospective study, telomere length was measured by quantitative PCR in baseline blood samples in a cohort of 300 patients with Barretts esophagus followed for a mean of 5.8 years. Leukocyte telomere length hazard ratios (HR) for risk of esophageal adenocarcinoma were calculated using multivariate Cox models. Results: Shorter telomeres were associated with increased esophageal adenocarcinoma risk (age-adjusted HR between top and bottom quartiles of telomere length, 3.45; 95% confidence interval, 1.35-8.78; P = 0.009). This association was still significant when individually or simultaneously adjusted for age, gender, nonsteroidal anti-inflammatory drug (NSAID) use, cigarette smoking, and waist-to-hip ratio (HR, 4.18; 95% confidence interval, 1.60-10.94; P = 0.004). The relationship between telomere length and cancer risk was particularly strong among NSAID nonusers, ever smokers, and patients with low waist-to-hip ratio. Conclusion: Leukocyte telomere length predicts risk of esophageal adenocarcinoma in patients with Barretts esophagus independently of smoking, obesity, and NSAID use. These results show the ability of leukocyte telomere length to predict the risk of future cancer and suggest that it might also have predictive value in other cancers arising in a setting of chronic inflammation. (Cancer Epidemiol Biomarkers Prev 2007;16(12):2649–55)