To evaluate the association of polycyclic aromatic hydrocarbon (PAH) exposure in esophageal epithelial tissue and esophageal squamous cell carcinoma (ESCC) case status in an ESCC case-control study in a high-risk population in northeastern Iran.
Immunohistochemical staining of tissue microarrays (TMAs) of non-tumoral esophageal biopsies from ESCC cases and control subjects. Immunohistochemistry was performed using monoclonal antibodies 8E11 and 5D11, raised against benzo[a]pyrene (B[a]P) diol epoxide (BPDE)-I-modified guanosine and BPDE-I-modified DNA, respectively. Staining intensity was quantified by image analysis, and the average staining in three replicates was calculated.
Rural region in northeastern Iran.
Cases were patients with biopsy-proven ESCC. Controls were GI clinic patients with no endoscopic or biopsy evidence of ESCC.
Main outcome measure
Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for the association between antibody staining intensity and ESCC case status.
Cultured ESCC cells exposed to B[a]P in vitro showed dose-dependent staining with 8E11, but not with 5D11. With 8E11, sufficient epithelial tissue was available in the TMA cores to analyze 91 cases and 103 controls. Compared to the lowest quintile of 8E11 staining in the controls, adjusted ORs (95% CIs) for the 2nd to 5th quintiles were 2.42, 5.77, 11.3, and 26.6 (5.21–135), respectively (P for trend < 0.001). With 5D11, 89 cases and 101 controls were analyzed. No association between staining and case status was observed (ORs (95% CIs) for the 2nd to 5th quintiles were 1.26, 0.88, 1.06, and 1.63 (0.63–4.21), P for trend = 0.40).
Dramatically higher levels of 8E11 staining were observed in non-tumoral esophageal epithelium from ESCC patients than from control subjects. This finding strengthens the evidence for a causal role for PAHs in esophageal carcinogenesis in northeastern Iran.
esophageal squamous cell carcinoma; polycyclic aromatic hydrocarbons; immunohistochemistry; tissue microarray
Populations in north central China are at high risk for gastric cancers (GC), and altered FAS-mediated cell signaling and/or apoptosis may contribute to this risk. We examined the association of 554 single nucleotide polymorphisms (SNPs) in 53 Fas signaling-related genes using a pathway-based approach in 1758 GC cases (1126 gastric cardia adenocarcinomas (GCA) and 632 gastric noncardia adenocarcinomas (GNCA)), and 2111 controls from a genome-wide association study (GWAS) of GC in ethnic Chinese. SNP associations with risk of overall GC, GCA and GNCA were evaluated using unconditional logistic regressions controlling for age, sex and study. Gene- and pathway-based associations were tested using the adaptive rank-truncated product (ARTP) method. Statistical significance was evaluated empirically by permutation. Significant pathway-based associations were observed for Fas signaling with risk of overall GC (P = 5.5E-04) and GCA (P = 6.3E-03), but not GNCA (P = 8.1E-02). Among examined genes in the Fas signaling pathway, MAP2K4, FAF1, MAPK8, CASP10, CASP8, CFLAR, MAP2K1, CAP8AP2, PAK2 and IKBKB were associated with risk of GC (nominal P < 0.05), and FAF1 and MAPK8 were significantly associated with risk of both GCA and GNCA (nominal P < 0.05). Our examination of genetic variation in the Fas signaling pathway is consistent with an association of altered Fas signaling and/or apoptosis with risk of GC. As one of the first attempts to investigate a pathway-level association, our results suggest that these genes and the Fas signaling pathway warrant further evaluation in relation to GC risk in other populations.
Gastric cancer; gastric cardia; gastric noncardia; Fas signaling; genetic variants; GWAS; single nucleotide polymorphisms; pathway genes
Maté tea is non-alcoholic infusion widely consumed in southern South America, and may increase risk of esophageal squamous cell carcinoma (ESCC) and other cancers due to polycyclic aromatic hydrocarbons and/or thermal injury.
We pooled two case-control studies: a 1988–2005 Uruguay study and a 1986–1992 multinational study in Argentina, Brazil, Paraguay and Uruguay, including 1,400 cases and 3,229 controls. We computed odds ratios (OR) and fitted a linear excess odds ratio (EOR) model for cumulative maté consumption in liters/day-year (LPDY).
The adjusted OR for ESCC with 95% confidence interval (CI) by ever compared with never use of maté was 1.60 (1.2,2.2). ORs increased linearly with LPDY (test of non-linearity, P=0.69). The estimate of slope (EOR/LPDY) was 0.009 (0.005,0.014) and did not vary with daily intake, indicating maté intensity did not influence the strength of association. EOR/LPDY estimates for consumption at warm, hot and very hot beverage temperatures were 0.004 (−0.002,0.013), 0.007 (0.003,0.013) and 0.016 (0.009,0.027), respectively, and differed significantly (P<0.01). EOR/LPDY estimates were increased in younger (<65) individuals and never alcohol drinkers, but these evaluations were post hoc, and were homogeneous by sex.
ORs for ESCC increased linearly with cumulative maté consumption and were unrelated to intensity, so greater daily consumption for shorter duration or lesser daily consumption for longer duration resulted in comparable ORs. The strength of association increased with higher mate temperatures.
Increased understanding of cancer risks with maté consumption enhances the understanding of the public health consequences given its purported health benefits.
Several epidemiologic studies have suggested an inverse association between female reproductive factors and risk of esophageal squamous cell carcinoma (ESCC), but the evidence is not conclusive. We investigated the association of the number of pregnancies, live-births, and miscarriages/stillbirths in women and the association of the number of children in both sexes with ESCC risk in Golestan Province, a high-risk area in Iran.
Data from 297 histopathologically confirmed ESCC cases (149 women) and 568 controls (290 women) individually matched to cases for age, sex, and neighborhood of residence were included in this analysis. Conditional logistic regression was used to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs).
The average numbers of live-births and miscarriages/stillbirths among controls were 8.2 and 0.8, respectively. Women with 6 or more live-births were at approximately one-third the risk of ESCC as those with 0–3 live-births; the OR (95% CI) for having 6–7 live-births was 0.33 (0.12–0.92). In contrast, the number of miscarriages/stillbirths was associated with an increase in ESCC risk. The OR (95% CI) for ≥ 3 versus no miscarriages/stillbirths was 4.43 (2.11–9.33). The number of children in women was suggestive an inverse association with ESCC, but this association was not statistically significant; in men, no association was seen.
The findings of this study support a protective influence of female hormonal factors on ESCC risk. However, further epidemiological and mechanistic studies are needed to prove a protective association.
case-control study; esophageal cancer; miscarriage; parity; reproductive; squamous cell carcinoma
Opium use has been associated with higher risk of cancers of the esophagus, bladder, larynx, and lung; however, no previous study has examined its association with gastric cancer. There is also little information on the associations between hookah (water pipe) smoking or the chewing of tobacco products and the risk of gastric cancer. In a case-control study in Golestan Province of Iran, we enrolled 309 cases of gastric adenocarcinoma (118 noncardia, 161 cardia, and 30 mixed-location adenocarcinomas) and 613 matched controls. Detailed information on long-term use of opium, tobacco products, and other covariates were collected using structured and validated lifestyle and food frequency questionnaires. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were obtained using conditional logistic regression models. Opium use was associated with an increased risk of gastric adenocarcinoma, with an adjusted OR (95% CI) of 3.1 (1.9 – 5.1), and this increased risk was apparent for both anatomic subsites (cardia and noncardia). There was a dose-response effect, and individuals with the highest cumulative opium use had the strongest association (OR: 4.5; 95%CI: 2.3-8.5). We did not find a statistically significant association between the use of any of the tobacco products and risk of gastric adenocarcinoma, overall or by anatomic subsite. We showed, for the first time, an association between opium use and gastric adenocarcinoma. Given that opium use is a traditional practice in many parts of the world, these results are of public health significance.
Opium; Adenocarcinoma; Cardia
The DNA repair pathways help to maintain genomic integrity and therefore genetic variation in the pathways could affect the propensity to develop cancer. Selected germline single nucleotide polymorphisms (SNPs) in the pathways have been associated with esophageal cancer and gastric cancer (GC) but few studies have comprehensively examined the pathway genes. We aimed to investigate associations between DNA repair pathway genes and risk of esophageal squamous cell carcinoma (ESCC) and GC, using data from a genome-wide association study in a Han Chinese population where ESCC and GC are the predominant cancers. In sum, 1942 ESCC cases, 1758 GC cases and 2111 controls from the Shanxi Upper Gastrointestinal Cancer Genetics Project (discovery set) and the Linxian Nutrition Intervention Trials (replication set) were genotyped for 1675 SNPs in 170 DNA repair-related genes. Logistic regression models were applied to evaluate SNP-level associations. Gene- and pathway-level associations were determined using the resampling-based adaptive rank-truncated product approach. The DNA repair pathways overall were significantly associated with risk of ESCC (P = 6.37 × 10−
4), but not with GC (P = 0.20). The most significant gene in ESCC was CHEK2 (P = 2.00 × 10−
6) and in GC was CLK2 (P = 3.02 × 10−
4). We observed several other genes significantly associated with either ESCC (SMUG1, TDG, TP53, GTF2H3, FEN1, POLQ, HEL308, RAD54B, MPG, FANCE and BRCA1) or GC risk (MRE11A, RAD54L and POLE) (P < 0.05). We provide evidence for an association between specific genes in the DNA repair pathways and the risk of ESCC and GC. Further studies are warranted to validate these associations and to investigate underlying mechanisms.
Poor oral health and tooth loss have been proposed as possible risk
factors for some chronic diseases, including gastric cancer. However only a
small number of studies have tested these associations.
We conducted a case-control study in Golestan Province, Iran, that
enrolled 309 cases diagnosed with gastric adenocarcinoma (118 noncardia, 161
cardia, and 30 mixed-locations) and 613 sex, age and neighborhood matched
controls. Data on oral health were obtained through physical examination and
questionnaire including tooth loss, the number of decayed, missing, and
filled teeth, and frequency of tooth brushing. Odds ratios (ORs) and
95% confidence intervals (95% CIs) were obtained using
conditional logistic regression models adjusted for potential confounders.
Standard one degree-of-freedom linear trend test and a multiple degree of
freedom global test of the effect of adding oral hygiene variables to the
model were also calculated.
Our results showed apparent associations between tooth loss and DMFT
score with risk of gastric cancer, overall and at each anatomic subsite.
However, these associations were not monotonic and were strongly confounded
by age. The results also showed that subjects who brushed their teeth less
than daily were at significantly higher risk for gastric cardia
adenocarcinoma OR (95% CI) of 5.6 (1.6–19.3).
We found evidence for an association between oral health and gastric
cancer, but the non- monotonic association, the relatively strong effect of
confounder adjustment, and inconsistent results across studies must temper
the strength of any conclusions.
Adenocarcinoma; Tooth loss; Oral health; Stomach
In China, esophageal cancer is the fourth leading cause of cancer death where essentially all cases are histologically esophageal squamous cell carcinoma (ESCC), in contrast to esophageal adenocarcinoma in the West. Globally, ESCC is 2.4 times more common among men than women and recently it has been suggested that sex hormones may be associated with the risk of ESCC. We examined the association between genetic variants in sex hormone metabolic genes and ESCC risk in a population from north central China with high-incidence rates. A total of 1026 ESCC cases and 1452 controls were genotyped for 797 unique tag single-nucleotide polymorphisms (SNPs) in 51 sex hormone metabolic genes. SNP-, gene- and pathway-based associations with ESCC risk were evaluated using unconditional logistic regression adjusted for age, sex and geographical location and the adaptive rank truncated product (ARTP) method. Statistical significance was determined through use of permutation for pathway- and gene-based associations. No associations were observed for the overall sex hormone metabolic pathway (P = 0.14) or subpathways (androgen synthesis: P = 0.30, estrogen synthesis: P = 0.15 and estrogen removal: P = 0.19) with risk of ESCC. However, six individual genes (including SULT2B1, CYP1B1, CYP3A7, CYP3A5, SHBG and CYP11A1) were significantly associated with ESCC risk (P < 0.05). Our examination of genetic variation in the sex hormone metabolic pathway is consistent with a potential association with risk of ESCC. These positive findings warrant further evaluation in relation to ESCC risk and replication in other populations.
Only a few studies in Western countries have investigated the association between gastroesophageal reflux disease (GERD) and mortality at the general population level and they have shown mixed results. This study investigated the association between GERD symptoms and overall and cause-specific mortality in a large prospective population-based study in Golestan Province, Iran.
Baseline data on frequency, onset time, and patient-perceived severity of GERD symptoms were available for 50001 participants in the Golestan Cohort Study (GCS). We identified 3107 deaths (including 1146 circulatory and 470 cancer-related) with an average follow-up of 6.4 years and calculated hazard ratios (HR) and 95% confidence intervals (CI) adjusted for multiple potential confounders.
Severe daily symptoms (defined as symptoms interfering with daily work or causing nighttime awakenings on a daily bases, reported by 4.3% of participants) were associated with cancer mortality (HR 1.48, 95% CI: 1.04-2.05). This increase was too small to noticeably affect overall mortality. Mortality was not associated with onset time or frequency of GERD and was not increased with mild to moderate symptoms.
We have observed an association with GERD and increased cancer mortality in a small group of individuals that had severe symptoms. Most patients with mild to moderate GERD can be re-assured that their symptoms are not associated with increased mortality.
Cardiovascular disease; Esophageal cancer; Gastroesophageal reflux disease; Mortality
Barrett's esophagus (BE) is a metaplastic precursor lesion of esophageal adenocarcinoma (EA), the most rapidly increasing cancer in western societies. While the prevalence of BE is increasing, the vast majority of EA occurs in patients with undiagnosed BE. Thus, we sought to identify genes that are altered in BE compared to the normal mucosa of the esophagus, and which may be potential biomarkers for the development or diagnosis of BE.
We performed gene expression analysis using HG-U133A Affymetrix chips on fresh frozen tissue samples of Barrett's metaplasia and matched normal mucosa from squamous esophagus (NE) and gastric cardia (NC) in 40 BE patients.
Using a cut off of 2-fold and P<1.12E-06 (0.05 with Bonferroni correction), we identified 1324 differentially-expressed genes comparing BE vs NE and 649 differentially-expressed genes comparing BE vs NC. Except for individual genes such as the SOXs and PROM1 that were dysregulated only in BE vs NE, we found a subset of genes (n = 205) whose expression was significantly altered in both BE vs NE and BE vs NC. These genes were overrepresented in different pathways, including TGF-β and Notch.
Our findings provide additional data on the global transcriptome in BE tissues compared to matched NE and NC tissues which should promote further understanding of the functions and regulatory mechanisms of genes involved in BE development, as well as insight into novel genes that may be useful as potential biomarkers for the diagnosis of BE in the future.
Gastroesophageal reflux disease (GERD) is a common cause of discomfort and morbidity worldwide. However, information on determinants of GERD from large-scale studies in low- to medium-income countries is limited. We investigated the factors associated with different measures of GERD symptoms, including frequency, patient-perceived severity, and onset time.
We performed a cross-sectional analysis of the baseline data from a population-based cohort study of ∼50,000 individuals in in Golestan Province, Iran. GERD symptoms in this study included regurgitation and/or heartburn.
Approximately 20% of participants reported at least weekly symptoms. Daily symptoms were less commonly reported by men, those of Turkmen ethnicity, and nass chewers. On the other hand, age, body mass index, alcohol drinking, cigarette smoking, opium use, lower socioeconomic status, and lower physical activity were associated with daily symptoms. Most of these factors showed similar associations with severe symptoms. Women with higher BMI and waist to hip ratio were more likely to report frequent and severe GERD symptoms. Hookah smoking (OR 1.34, 95% CI 1.02–1.75) and opium use (OR 1.70, 95% CI 1.55–1.87) were associated with severe symptoms, whereas nass chewing had an inverse association (OR 0.87, 95% CI 0.76–0.99). After exclusion of cigarette smokers, hookah smoking was still positively associated and nass chewing was inversely associated with GERD symptoms (all frequencies combined).
GERD is common in this population. The associations of hookah and opium use and inverse association of nass use with GERD symptoms are reported for the first time. Further studies are required to investigate the nature of these associations. Other determinants of GERD were mostly comparable to those reported elsewhere.
Water-pipe and smokeless tobacco use have been associated with several adverse health outcomes. However, little information is available on the association between water-pipe use and heart disease (HD). Therefore, we investigated the association of smoking water-pipe and chewing nass (a mixture of tobacco, lime, and ash) with prevalent HD.
Baseline data (collected in 2004–2008) from a prospective population-based study in Golestan Province, Iran.
50,045 residents of Golestan (40–75 years old; 42.4% male).
Main outcome measures
ORs and 95% CIs from multivariate logistic regression models for the association of water-pipe and nass use with HD prevalence.
A total of 3051 (6.1%) participants reported a history of HD, and 525 (1.1%) and 3726 (7.5%) reported ever water-pipe or nass use, respectively. Heavy water-pipe smoking was significantly associated with HD prevalence (highest level of cumulative use versus never use, OR= 3.75; 95% CI 1.52 – 9.22; P for trend= 0.04). This association persisted when using different cutoff points, when restricting HD to those taking nitrate compound medications, and among never cigarette smokers. There was no significant association between nass use and HD prevalence (highest category of use versus never use, OR= 0.91; 95% CI 0.69 – 1.20).
Our study suggests a significant association between HD and heavy water-pipe smoking. Although the existing evidence suggesting similar biological consequences of water-pipe and cigarette smoking make this association plausible, results of our study were based on a modest number of water-pipe users and need to be replicated in further studies.
hookah; ischemic heart disease; nass; tobacco; water-pipe
Esophageal cancer is unusually frequent in western Kenya, despite the low prevalence of classical risk factors such as heavy drinking and tobacco smoking. Among Kenyans consumption of fermented milk is an old tradition. Our hypothesis is that alcohol and acetaldehyde are produced during the fermentation process and that their carcinogenic potential contributes to the high incidence of esophageal cancer.
Eight samples of mursik milk starter cultures were collected from different Kalenjin families in the Rift Valley province, Western Kenya. A protocol provided by the families was used for milk fermentation. Ethanol and acetaldehyde levels were measured by gas chromatography. The microbial flora in starter cultures was identified by 16S and 18S sequencing.
7/8 starter cultures produced mutagenic (>100 µM) levels of acetaldehyde and 4/8 starter cultures produced >1000 µM of acetaldehyde. The highest alcohol levels (mean 79.4 mM) were detected in the four fermented milks with highest acetaldehyde production. The mean number of microbial species in the starter cultures was 5 (range 2–8). Yeasts were identified in all starter cultures (mean 1.5 species/milk) but their proportion of the total microbial count varied markedly (mean 35%, range 7–90%). A combination of yeast and lactobacilli, especially Candida krusei with Lactobacillus kefiriwith the exclusion of other species, seemed to correlate with higher acetaldehyde and ethanol levels.
Significant levels of ethanol and acetaldehyde were produced during mursik fermentation.
When ingested several times daily the repeated exposure to carcinogenic levels of acetaldehyde may contribute to esophageal carcinogenesis.
Candida; carcinogenesis; ethanol; fermented milk; lactobacilli
Prospective epidemiologic data on the association between vitamin D and mortality are limited, particularly in Asian populations. Among subjects in Linxian, China, the authors aimed to test whether baseline serum 25-hydroxyvitamin D (25(OH)D) concentrations in a prospective cohort were associated with all-cause mortality and cause-specific mortality rates over 24 years of follow-up (1986–2010). Serum 25(OH)D concentrations were measured in 1,101 subjects using an immunoassay. Hazard ratios and 95% confidence intervals were calculated using Cox regression models that were adjusted for age, sex, tobacco smoking, alcohol drinking, and hypertension. The 25th, 50th, and 75th percentile concentrations of 25(OH)D were 19.6, 31.9, and 48.4 nmol/L, respectively. During follow-up, 793 subjects died, including 279 who died of cerebrovascular accident, 217 who died of cancer, and 200 cardiovascular disease deaths. All-cause mortality was not associated with 25(OH)D concentrations using continuous models (for every 15 nmol/L, hazard ratio = 1.01, 95% confidence interval: 0.97, 1.05) or quartile models (fourth vs. first quartiles, hazard ratio = 1.06, 95% confidence interval: 0.87, 1.30; P for trend = 0.731). The authors also found no association with the cause-specific mortality outcomes. Results were similar for men and women. This study showed that prediagnostic serum 25(OH)D concentrations were not associated with all-cause or cause-specific mortality rates in this Chinese population who had low levels of vitamin D.
cancer; cardiovascular diseases; China; mortality; vitamin D
Iron is an essential micronutrient that can have carcinogenic effects when at high or low concentrations. Previous studies of iron in relation to gastric cancer have not assessed subtype-specific relationships. We used the prospective ATBC Cancer Prevention Study to assess whether iron metrics were associated with gastric cardia cancer (GCC) and gastric noncardia cancer (GNCC).
We selected 341 incident gastric cancer cases (86 cardia, 172 noncardia, and 83 non-specified), accrued during 22 years of follow-up, and 341 individually matched controls. We measured prediagnostic serum iron, ferritin, unsaturated iron binding capacity (UIBC), and C-reactive protein. Total iron binding capacity (TIBC) and transferrin saturation were estimated from these metrics. Dietary iron exposures were estimated from a food frequency questionnaire. Multivariable logistic regression was used for analysis.
Serum iron metrics were not associated with GCC, except for a potential ‘n’-shaped relationship with TIBC (global p=0.038). GNCC was inversely associated with serum ferritin (global p=0.024), serum iron (global p=0.060) and, possibly, transferrin saturation. TIBC appeared to share a ‘u’shaped relationship with GNCC (global p=0.033). Dietary iron exposures were not associated with either subsite. Adjustment for Helicobacter pylori and gastric atrophy had little effect on observed associations.
We found little evidence for the involvement of iron exposure in the pathogenesis of GCC. GNCC was associated with an iron profile similar to that of iron deficiency.
Helicobacter pylori; Iron; Nested Case-Control Studies; Prospective Studies; Stomach Neoplasms
The epidermal growth factor receptor (EGFR) signaling pathway regulates cell proliferation, differentiation, and survival, and is frequently dysregulated in esophageal and gastric cancers. Few studies have comprehensively examined the association between germline genetic variants in the EGFR pathway and risk of esophageal and gastric cancers. Based on a genome-wide association study in a Han Chinese population, we examined 3443 SNPs in 127 genes in the EGFR pathway for 1942 esophageal squamous cell carcinomas (ESCCs), 1758 gastric cancers (GCs), and 2111 controls. SNP-level analyses were conducted using logistic regression models. We applied the resampling-based adaptive rank truncated product approach to determine the gene- and pathway-level associations. The EGFR pathway was significantly associated with GC risk (P = 2.16×10−3). Gene-level analyses found 10 genes to be associated with GC, including FYN, MAPK8, MAP2K4, GNAI3, MAP2K1, TLN1, PRLR, PLCG2, RPS6KB2, and PIK3R3 (P<0.05). For ESCC, we did not observe a significant pathway-level association (P = 0.72), but gene-level analyses suggested associations between GNAI3, CHRNE, PAK4, WASL, and ITCH, and ESCC (P<0.05). Our data suggest an association between specific genes in the EGFR signaling pathway and risk of GC and ESCC. Further studies are warranted to validate these associations and to investigate underlying mechanisms.
Linzhou, China has one of the highest rates of esophageal squamous cell carcinoma in the world. Exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BaP), may play a role in this increased risk. To better understand PAH sources, we measured PAHs in the air and food of 20 non-smokers over multiple days and compared the concentrations to a urinary PAH biomarker, 1-hydroxypyrene glucuronide (1-OHPG). Sampling occurred over four consecutive days. Kitchen air samples (days 2–3) and duplicate diet samples (days 1–4) were analyzed for 14 or more unique PAHs, including BaP. Daily urine samples (days 1–3) were analyzed for 1-OHPG. Mixed-effects models were used to evaluate the associations between air or food PAH concentrations and urine 1-OHPG concentrations. The median kitchen air BaP concentration was 10.2 ng/m3 (inter-quartile range (IQR): 5.1–20.2 ng/m3). The median daily food BaP concentration and intake were 0.08 ng/g (IQR=0.04–0.16 ng/g) and 86 ng/day (IQR=41–142 ng/day), respectively. The median 1-OHPG concentration was 3.36 pmol/mL (IQR=2.09–6.98 pmol/mL). In mixed-effects models, 1-OHPG concentration increased with same-day concentration of food BaP (p=0.07). Though PAH concentrations in air were not associated with 1-OHPG concentrations, the high concentrations of PAHs in both air and food suggest that they are both important routes of exposure to PAHs in this population. Further evaluation of the role of PAH exposure from air and food in the elevated rates of esophageal cancer in this region is warranted.
polycyclic aromatic hydrocarbons; cancer; China; dietary exposure; inhalation exposure; biomonitoring; multimedia exposure assessment
Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P< 5 × 10−8, and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19–1.40) and P= 7.63 × 10−10. An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.
Fumonisin B1 (FB1), a mycotoxin that contaminates corn in certain climates, has been demonstrated to cause hepatocellular cancer (HCC) in animal models. Whether a relationship between FB1 and HCC exists in humans is not known. To examine the hypothesis, we conducted case-control studies nested within two large cohorts in China; the Haimen City Cohort and the General Population Study of the Nutritional Intervention Trials cohort in Linxian. In the Haimen City Cohort, nail FB1 levels were determined in 271 HCC cases and 280 controls. In the General Population Nutritional Intervention Trial, nail FB1 levels were determined in 72 HCC cases and 147 controls. In each population, odds ratios and 95% confidence intervals (95%CI) from logistic regression models estimated the association between measurable FB1 and HCC, adjusting for hepatitis B virus infection and other factors. A meta-analysis that included both populations was also conducted. The analysis revealed no statistically significant association between FB1 and HCC in either Haimen City (OR=1.10, 95%CI=0.64–1.89) or in Linxian (OR=1.47, 95%CI=0.70–3.07). Similarly, the pooled meta-analysis showed no statistically significant association between FB1 exposure and HCC (OR=1.22, 95%CI=0.79–1.89). These findings, although somewhat preliminary, do not support an associated between FB1 and HCC.
fumonisin; hepatocellular carcinoma; cohort study; China; epidemiology
The role of human papillomavirus (HPV) in the causation of esophageal squamous cell carcinoma is unclear. We examined the associations between esophageal squamous cell carcinoma and 28 centrally measured HPV serological markers in serum from six existing case–control studies conducted in regions with differing background risks of esophageal cancer.
We used centralized multiplex serology to test serum samples from 1561 case subjects and 2502 control subjects from six case–control studies for antibodies to the major HPV capsid protein (L1) and/or the early proteins E6 and/or E7 of eight high-risk, two low-risk, and four cutaneous HPV types. Study-specific odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using conditional logistic regression with adjustment for smoking, alcohol consumption, and other potential confounders. Pooled odds ratios and 95% confidence intervals were calculated using either a linear mixed-effects approach or a joint fixed-effects approach. All statistical tests were two-sided.
We found statistically significant associations between esophageal squamous cell carcinoma and antibodies to E6 for HPV16 (OR = 1.89, 95% CI = 1.09 to 3.29, P = .023) and HPV6 (OR = 2.53, 95% CI = 1.51 to 4.25, P < .001) but not for other tested HPV types. There were no statistically significant associations between esophageal squamous cell carcinoma and antibodies to E7 for any of the tested HPV types. Simultaneous seropositivity for HPV16 E6 and E7 was rare (four case subjects, two control subjects; OR = 5.57, 95% CI = 0.90 to 34.35; P = .064). We also found statistically significant associations between esophageal squamous cell carcinoma and capsid antibodies for the high-risk mucosal type HPV33 L1 (OR = 1.30, 95% CI = 1.00 to 1.69; P = .047) and the low-risk mucosal types HPV6 (OR = 1.22, 95% CI = 1.05 to 1.42; P = .010) and HPV11 (OR = 1.30, 95% CI = 1.09 to 1.56, P = .0036).
We found limited serological evidence of an association between esophageal squamous cell carcinoma and HPV in the populations studied. Although HPV does not appear to be an important risk factor for esophageal squamous cell carcinoma, we cannot exclude the possibility that certain HPV types may be involved in a small subset of cancers.
Drinking maté, common in southern South America, may increase the risk of esophageal squamous cell carcinoma (ESCC). In 2006, we found high but variable polycyclic aromatic hydrocarbon (PAH) content in commercial yerba maté samples from eight Brazilian brands. The PAH content of new samples from the same brands, purchased in 2008, and four brands from a single manufacturer processed in different ways, obtained in 2010, were quantified to determine whether PAH concentration was still high, PAH content variation was brand specific, and whether processing method affects PAH content of commercial yerba maté. Concentrations of individual PAHs were quantified using gas chromatography/mass spectrometry with deuterated PAHs as internal standards. Median total PAH concentration was 1500 ng/g (range: 625 to 3710 ng/g) and 1090 ng/g (621 to 1990 ng/g) in 2008 and 2010 samples, respectively. Comparing 2006 and 2008 samples, some brands had high PAH concentrations in both years, while PAH concentration changed considerably in others. Benzo[a]pyrene concentrations ranged from 11.9 to 99.3 ng/g and 5.11 to 21.0 ng/g in 2008 and 2010 samples, respectively. The 2010 sample processed without touching smoke had the lowest benzo[a]pyrene content. These results support previous findings of very high total and carcinogenic PAH concentrations in yerba maté, perhaps contributing to the high incidence of ESCC in southern South America. The large PAH content variation by brand, batch and processing method suggests it may be possible to reduce the content of carcinogenic PAHs in commercial yerba maté, making it a healthier beverage.
Polycyclic Aromatic Hydrocarbons; Yerba Maté; Carcinogens; Esophageal Cancer; Benzo(α)pyrene; Processing Method; Lifestyle
Oesophageal cancers rank as the eighth most common cancer and the sixth most common cause of cancer death, worldwide. Gastric atrophy, as determined by a low serum pepsinogen I/II ratio, may be associated with an increased risk of oesophageal squamous cell carcinoma (OSCC). Ghrelin, a hormone which, like pepsinogen, is produced in the fundic glands of the stomach, may be a sensitive and specific marker of gastric atrophy, but its association with OSCC is not known.
To examine the relationship between baseline serum ghrelin concentration and subsequent risk of OSCC, we conducted a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study. 82 cases of OSCC were matched (1:1) by age and date of blood draw to controls from the ATBC study. Serum ghrelin was measured by radioimmunoassay. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using conditional logistic regression with adjustment for potential confounders.
For those individuals in the lowest quartile of serum ghrelin, compared to those in the highest, the multivariate odds ratio of subsequent OSCC was 6.83 (95% CI: 1.46, 31.84). These associations were dose dependent (P for trend = 0.005 for both), and independent of the effects of low pepsinogen I/II ratio (a marker of gastric fundic atrophy) and Helicobacter pylori infection. The significance of these associations remained even for individuals developing OSCC up to 10 years after baseline ghrelin measurement, though they become attenuated after 10 years.
Lower baseline concentrations of serum ghrelin were associated with an increase in risk of OSCC. Further studies are needed to confirm this finding in other populations and to explore the role of ghrelin in the aetiology of OSCC.
ghrelin; oesophageal squamous cell carcinoma; atrophy
Esophageal cancer has a strikingly uneven geographical distribution, resulting in focal endemic areas in several countries. One such endemic area is in western Kenya. We conducted a retrospective review of all pathology-confirmed malignancies diagnosed at Tenwek Hospital, Bomet District, between January 1999 and September 2007. Tumor site, histology, sex, age, ethnicity, and location of residence were recorded. Cases were analyzed within and outside a traditional catchment area defined as ≤ 50 km from the hospital. Since 1999, the five most common cancer sites were esophagus, stomach, prostate, colorectum, and cervix. Esophageal cancer accounted for 914 (34.6%) of the 2643 newly diagnosed cancers, and showed increasing trends within and outside the catchment area. Fifty-eight (6.3%) patients were ≤ 30 years old and 9 (1%) were ≤ 20 years old; the youngest patient was 14 at diagnosis. Young cases (≤30) were more common among patients of Kalenjin ethnicity (9.2%) than among other ethnicities (1.7%) (odds ratio (95%CI) 5.7 (2.1–15.1)). This area of western Kenya is a high-risk region for esophageal cancer, and appears unique in its large proportion of young patients. Our findings support the need for further study of both environmental and genetic risk factors for esophageal cancer in this area.
Esophageal cancer; Kenya; age of onset; ethnicity
Iodine concentrates in gastric tissue and may act as an antioxidant for the stomach. We previously showed that self-reported goiter was associated with significantly increased risk of gastric noncardia adenocarcinoma (GNCA) and non-significantly increased risks of gastric cardia adenocarcinoma (GCA) and esophageal squamous cell carcinoma (ESCC) in a prospective case-cohort study in a high-risk population in China. Negatively correlated with iodine levels, serum thyroglobulin (Tg) is a more sensitive biomarker of iodine deficiency than goiter. This study aimed to determine whether baseline serum Tg was also associated with development of GNCA, GCA, and ESCC in the same cohort, the Linxian General Population Nutrition Intervention Trial. Sera from approximately 200 subjects of each case type and 400 non-cases were tested for serum Tg concentration using appropriate assays. Tg was modeled as sex- and assay-specific quartiles in Cox regression models adjusted for age, smoking, alcohol, Helicobacter pylori status, pepsinogens I/II ratio, family history, and commune of residence. In the final combined analysis, participants in the highest quartile of serum Tg, compared to those in the lowest quartile, had adjusted Hazard Ratios of 0.88 (95% confidence interval 0.50–1.52), 1.14 (0.63–2.05), and 0.78 (0.47–1.31) for GNCA, GCA, and ESCC, respectively. Using serum Tg, a sensitive biomarker of iodine deficiency, we found no association between serum Tg concentrations and risk of these upper gastrointestinal (UGI) cancers in the study population. Our results do not support the hypothesis that iodine deficiency, as assessed by serum Tg, is associated with an increased risk of UGI cancers.
iodine deficiency; esophageal cancer; gastric cancer; thyroglobulin; China
Cancers of the upper gastrointestinal tract remain a significant cause of morbidity and mortality. Cysteine, known to be involved in a myriad of immuno-modulatory, anti-oxidant, and anti-carcinogenic pathways, has not been investigated in the aetiology of oesophageal or gastric cancers. To examine the relationship between serum cysteine concentration and risk of these cancers we conducted a nested case-cohort study within the General Population Nutrition Intervention Trial in Linxian, China.
498 oesophageal squamous cell carcinomas (OSCC) and 255 gastric cardia adenocarcinomas (GCA) were matched by age and sex to 947 individuals from the wider cohort. We calculated hazard ratios (HR) and 95% confidence intervals (95% CI) using the case-cohort estimator for the Cox proportional hazards models, stratified on age and sex, with adjustment for potential confounders.
Higher concentrations of serum cysteine were significantly associated with a lower risk of both OSCC and GCA. For those in the highest quartile of serum cysteine, compared to those in the lowest, the multivariate HRs were 0.70 for OSCC (95% CI: 0.51, 0.98) and 0.59 for GCA (95% CI: 0.38, 0.91). These associations were dose dependent (P for trend = 0.006 and 0.008, respectively). These inverse associations were not significantly modified by other risk factors, with the exception of age, where a stronger association was noted among persons in the older age strata.
Higher serum concentrations of cysteine were associated with a significantly reduced risk of OSCC and GCA. Cysteine should be further investigated for its potential as a chemopreventive agent for upper gastrointestinal cancers.
oesophageal squamous cell carcinoma; gastric cardia cancer; hazard ratio; cysteine