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1.  Variation in PAH-related DNA adduct levels among non-smokers: the role of multiple genetic polymorphisms and nucleotide excision repair phenotype 
Polycyclic aromatic hydrocarbons (PAHs) likely play a role in many cancers even in never-smokers. We tried to find a model to explain the relationship between variation in PAH-related DNA adduct levels among people with similar exposures, multiple genetic polymorphisms in genes related to metabolic and repair pathways, and nucleotide excision repair (NER) capacity. In 111 randomly-selected female never-smokers from the Golestan Cohort Study in Iran, we evaluated 21 SNPs in 14 genes related to xenobiotic metabolism and 12 SNPs in 8 DNA repair genes. NER capacity was evaluated by a modified comet assay, and aromatic DNA adduct levels were measured in blood by 32P-postlabelling. Multivariable regression models were compared by Akaike’s information criterion (AIC). Aromatic DNA adduct levels ranged between 1.7 and 18.6 per 108 nucleotides (mean: 5.8±3.1). DNA adduct level was significantly lower in homozygotes for NAT2 slow alleles and ERCC5 non risk-allele genotype, and was higher in the MPO homozygote risk-allele genotype. The sum of risk alleles in these genes significantly correlated with the log-adduct level (r=0.4, p<0.001). Compared with the environmental model, adding phase I SNPs and NER capacity provided the best fit, and could explain 17% more of the variation in adduct levels. NER capacity was affected by polymorphisms in the MTHFR and ERCC1 genes. Female non-smokers in this population had PAH-related DNA adduct levels 3-4 times higher than smokers and occupationally-exposed groups in previous studies, with large inter-individual variation which could best be explained by a combination of phase I genes and NER capacity.
PMCID: PMC3597757  PMID: 23175176
Polycyclic aromatic hydrocarbons; DNA adducts; nucleotide excision repair; polymorphism
2.  Smoking water-pipe, chewing nass, and prevalence of heart disease – A cross-sectional analysis of baseline data from the Golestan Cohort Study, Iran 
Heart (British Cardiac Society)  2012;99(4):272-278.
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.
Cross-sectional study.
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.
PMCID: PMC3671096  PMID: 23257174
hookah; ischemic heart disease; nass; tobacco; water-pipe
3.  Alcohol and acetaldehyde in African fermented milk mursik – A possible etiological factor for high incidence of esophageal cancer in western Kenya 
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.
PMCID: PMC3538938  PMID: 23155139
Candida; carcinogenesis; ethanol; fermented milk; lactobacilli
4.  Prospective Study of Serum 25-Hydroxyvitamin D Concentration and Mortality in a Chinese Population 
American Journal of Epidemiology  2012;176(11):1043-1050.
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.
PMCID: PMC3571239  PMID: 23139250
cancer; cardiovascular diseases; China; mortality; vitamin D
5.  Iron in Relation to Gastric Cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study 
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.
PMCID: PMC3493744  PMID: 23001240
Helicobacter pylori; Iron; Nested Case-Control Studies; Prospective Studies; Stomach Neoplasms
6.  Genome-wide association studies of gastric adenocarcinoma and esophageal squamous cell carcinoma identify a shared susceptibility locus in PLCE1 at 10q23 
Nature genetics  2012;44(10):1090-1097.
We conducted a genome-wide association study of gastric cancer (GC) and esophageal squamous cell carcinoma (ESCC) in ethnic Chinese subjects in which we genotyped 551,152 single nucleotide polymorphisms (SNPs). We report a combined analysis of 2,240 GC cases, 2,115 ESCC cases, and 3,302 controls drawn from five studies. In logistic regression models adjusted for age, sex, and study, multiple variants at 10q23 had genome-wide significance for GC and ESCC independently. A notable signal was rs2274223, a nonsynonymous SNP located in PLCE1, for GC (P=8.40×1010; per allele odds ratio (OR) = 1.31) and ESCC (P=3.85×10−9; OR = 1.34). The association with GC differed by anatomic subsite. For tumors located in the cardia the association was stronger (P=4.19 × 10−15; OR= 1.57) and for those located in the noncardia stomach it was absent (P=0.44; OR=1.05). Our findings at 10q23 could provide insight into the high incidence rates of both cancers in China.
PMCID: PMC3513832  PMID: 22960999
7.  A multi-day environmental study of polycyclic aromatic hydrocarbon exposure in a high-risk region for esophageal cancer in China 
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.
PMCID: PMC3504638  PMID: 22805987
polycyclic aromatic hydrocarbons; cancer; China; dietary exposure; inhalation exposure; biomonitoring; multimedia exposure assessment
8.  Genotypic variants at 2q33 and risk of esophageal squamous cell carcinoma in China: a meta-analysis of genome-wide association studies 
Abnet, Christian C. | Wang, Zhaoming | Song, Xin | Hu, Nan | Zhou, Fu-You | Freedman, Neal D. | Li, Xue-Min | Yu, Kai | Shu, Xiao-Ou | Yuan, Jian-Min | Zheng, Wei | Dawsey, Sanford M. | Liao, Linda M. | Lee, Maxwell P. | Ding, Ti | Qiao, You-Lin | Gao, Yu-Tang | Koh, Woon-Puay | Xiang, Yong-Bing | Tang, Ze-Zhong | Fan, Jin-Hu | Chung, Charles C. | Wang, Chaoyu | Wheeler, William | Yeager, Meredith | Yuenger, Jeff | Hutchinson, Amy | Jacobs, Kevin B. | Giffen, Carol A. | Burdett, Laurie | Fraumeni, Joseph F. | Tucker, Margaret A. | Chow, Wong-Ho | Zhao, Xue-Ke | Li, Jiang-Man | Li, Ai-Li | Sun, Liang-Dan | Wei, Wu | Li, Ji-Lin | Zhang, Peng | Li, Hong-Lei | Cui, Wen-Yan | Wang, Wei-Peng | Liu, Zhi-Cai | Yang, Xia | Fu, Wen-Jing | Cui, Ji-Li | Lin, Hong-Li | Zhu, Wen-Liang | Liu, Min | Chen, Xi | Chen, Jie | Guo, Li | Han, Jing-Jing | Zhou, Sheng-Li | Huang, Jia | Wu, Yue | Yuan, Chao | Huang, Jing | Ji, Ai-Fang | Kul, Jian-Wei | Fan, Zhong-Min | Wang, Jian-Po | Zhang, Dong-Yun | Zhang, Lian-Qun | Zhang, Wei | Chen, Yuan-Fang | Ren, Jing-Li | Li, Xiu-Min | Dong, Jin-Cheng | Xing, Guo-Lan | Guo, Zhi-Gang | Yang, Jian-Xue | Mao, Yi-Ming | Yuan, Yuan | Guo, Er-Tao | Zhang, Wei | Hou, Zhi-Chao | Liu, Jing | Li, Yan | Tang, Sa | Chang, Jia | Peng, Xiu-Qin | Han, Min | Yin, Wan-Li | Liu, Ya-Li | Hu, Yan-Long | Liu, Yu | Yang, Liu-Qin | Zhu, Fu-Guo | Yang, Xiu-Feng | Feng, Xiao-Shan | Wang, Zhou | Li, Yin | Gao, She-Gan | Liu, Hai-Lin | Yuan, Ling | Jin, Yan | Zhang, Yan-Rui | Sheyhidin, Ilyar | Li, Feng | Chen, Bao-Ping | Ren, Shu-Wei | Liu, Bin | Li, Dan | Zhang, Gao-Fu | Yue, Wen-Bin | Feng, Chang-Wei | Qige, Qirenwang | Zhao, Jian-Ting | Yang, Wen-Jun | Lei, Guang-Yan | Chen, Long-Qi | Li, En-Min | Xu, Li-Yan | Wu, Zhi-Yong | Bao, Zhi-Qin | Chen, Ji-Li | Li, Xian-Chang | Zhuang, Xiang | Zhou, Ying-Fa | Zuo, Xian-Bo | Dong, Zi-Ming | Wang, Lu-Wen | Fan, Xue-Pin | Wang, Jin | Zhou, Qi | Ma, Guo-Shun | Zhang, Qin-Xian | Liu, Hai | Jian, Xin-Ying | Lian, Sin-Yong | Wang, Jin-Sheng | Chang, Fu-Bao | Lu, Chang-Dong | Miao, Jian-Jun | Chen, Zhi-Guo | Wang, Ran | Guo, Ming | Fan, Zeng-Lin | Tao, Ping | Liu, Tai-Jing | Wei, Jin-Chang | Kong, Qing-Peng | Fan, Lei | Wang, Xian-Zeng | Gao, Fu-Sheng | Wang, Tian-Yun | Xie, Dong | Wang, Li | Chen, Shu-Qing | Yang, Wan-Cai | Hong, Jun-Yan | Wang, Liang | Qiu, Song-Liang | Goldstein, Alisa M. | Yuan, Zhi-Qing | Chanock, Stephen J. | Zhang, Xue-Jun | Taylor, Philip R. | Wang, Li-Dong
Human Molecular Genetics  2012;21(9):2132-2141.
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.
PMCID: PMC3315211  PMID: 22323360
9.  InterSCOPE Study: Associations Between Esophageal Squamous Cell Carcinoma and Human Papillomavirus Serological Markers 
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.
PMCID: PMC3260131  PMID: 22228147
10.  Significant variation in the concentration of carcinogenic polycyclic aromatic hydrocarbons in yerba maté samples by brand, batch and processing method 
Environmental science & technology  2012;46(24):13488-13493.
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.
PMCID: PMC3525749  PMID: 23101992
Polycyclic Aromatic Hydrocarbons; Yerba Maté; Carcinogens; Esophageal Cancer; Benzo(α)pyrene; Processing Method; Lifestyle
11.  Parameters predicting lymph node metastasis in patients with superficial esophageal squamous cell carcinoma 
Endoscopic resection is a less invasive treatment than esophagectomy for superficial esophageal squamous cell carcinoma, but patients with lymph node metastasis need additional treatment after endoscopic resection. The purpose of this study was to establish a set of indicators to identify superficial esophageal squamous cell carcinoma patients at a high risk of metastasis. 271 superficial esophageal squamous cell carcinoma esophagectomy cases were reviewed retrospectively. The relationships between clinicopathological parameters and immunohistochemical findings (p53, Cyclin D1, EGFR and VEGF) on tissue microarrays, on the one hand, and lymph node metastasis were assessed by univariate and multivariate logistic regression analyses. Patients with intraluminal masses and ulcerated masses had a high risk of lymph node metastasis. Patients with superficial esophageal squamous cell carcinoma 1) thinner than 1200µm; 2) confined to the mucosa; 3) with submucosal invasion <250µm; 4) with submucosal invasion ≥250µm but with negative VEGF expression and well/moderately differentiated or basaloid histology; or 5) with submucosal invasion ≥250µm but with weak VEGF expression and well differentiated histology had almost no risk of lymph node metastasis. We recommend endoscopic resection for all erosive, papillary and plaque-like superficial esophageal squamous cell carcinomas where endoscopic resection is clinically feasible, and esophagectomy for all other erosive, papillary and plaque-like cases and all intraluminal masses and ulcerated tumors. No additional treatment is needed for endoscopic resection cases with superficial esophageal squamous cell carcinoma 1) thinner than 1200µm; 2) confined to the mucosa; 3) with submucosal invasion <250µm; 4) with submucosal invasion ≥250µm but with negative VEGF expression and well/moderately differentiated or basaloid histology; or 5) with submucosal invasion ≥250µm but with weak VEGF expression and well differentiated histology. These clinical and pathological criteria should enable more accurate selection of patients for these procedures.
PMCID: PMC3505024  PMID: 22627741
superficial cancer; esophageal cancer; squamous cell carcinoma; endoscopic resection; lymph node metastasis
12.  Attributable Causes of Esophageal Cancer Incidence and Mortality in China 
PLoS ONE  2012;7(8):e42281.
To estimate the contribution of tobacco smoking, alcohol drinking, low vegetable intake and low fruit intake to esophageal cancer mortality and incidence in China.
Methodology/Principal Findings
We calculated the proportion of esophageal cancer attributable to four known modifiable risk factors [population attributable fraction (PAF)]. Exposure data was taken from meta-analyses and large-scale national surveys of representative samples of the Chinese population. Data on relative risks were also from meta-analyses and large-scale prospective studies. Esophageal cancer mortality and incidence came from the 3rd national death cause survey and population-based cancer registries in China. We estimated that 87,065 esophageal cancer deaths (men 67,686; women: 19,379) and 108,206 cases (men: 83,968, women: 24,238) were attributable to tobacco smoking, alcohol drinking, low vegetable intake and low fruit intake in China in 2005. About 17.9% of esophageal cancer deaths among men and 1.9% among women were attributable to tobacco smoking. About 15.2% of esophageal cancer deaths in men and 1.3% in women were caused by alcohol drinking. Low vegetable intake was responsible for 4.3% esophageal cancer deaths in men and 4.1% in women. The fraction of esophageal cancer deaths attributable to low fruit intake was 27.1% in men and 28.0% in women. Overall, 46% of esophageal cancers (51% in men and 33% in women) were attributable to these four modifiable risk factors.
Tobacco smoking, alcohol drinking, low vegetable intake and low fruit intake were responsible for 46% of esophageal cancer mortality and incidence in China in 2005. These findings provide useful data for developing guidelines for esophageal cancer prevention and control in China.
PMCID: PMC3410925  PMID: 22876312
13.  Predicting esophageal squamous cell carcinoma and squamous dysplasia: risk modeling in a high risk area in Iran 
Archives of Iranian Medicine  2012;15(1):18-21.
Identifying people at higher risk of having squamous dysplasia, the precursor lesion for esophageal squamous cell carcinoma (ESCC), would allow targeted endoscopic screening.
We used multivariate logistic regression models to predict ESCC and dysplasia as outcomes. The ESCC model was based on data from the Golestan Case-Control Study (total n=871; cases=300), and the dysplasia model was based on data from a cohort of subjects from a GI clinic in Northeast Iran (total n=724; cases=26). In each of these analyses, we fit a model including all risk factors known in this region to be associated with ESCC. Individual risks were calculated using the linear combination of estimated regression coefficients and individual-specific values for covariates. We used cross-validation to determine the area under the curve (AUC) and to find the optimal cut points for each of the models.
The model had an area under the curve of 0.77 (95% CI: 0.74–0.80) to predict ESCC with 74% sensitivity and 70.4% specificity for the optimum cut point. The area under the curve was 0.71 (95% CI: 0.64–0.79) for dysplasia diagnosis, and the classification table optimized at 61.5% sensitivity and 69.5% specificity. In this population, the positive and negative predictive values for diagnosis of dysplasia were 6.8% and 97.8%, respectively.
Our models were able to discriminate between ESCC cases and controls in about 77%, and between individuals with and without squamous dysplasia in about 70% of the cases. Using risk factors to predict individual risk of ESCC or squamous dysplasia still has limited application in clinical practice, but such models may be suitable for selecting high risk individuals in research studies, or increasing the pretest probability for other screening strategies.
PMCID: PMC3294378  PMID: 22208438
14.  Is Opium a Real Risk Factor for Esophageal Cancer or Just a Methodological Artifact? Hospital and Neighborhood Controls in Case-Control Studies 
PLoS ONE  2012;7(3):e32711.
Control selection is a major challenge in epidemiologic case-control studies. The aim of our study was to evaluate using hospital versus neighborhood control groups in studying risk factors of esophageal squamous cell carcinoma (ESCC).
Methodology/Principal Findings
We compared the results of two different case-control studies of ESCC conducted in the same region by a single research group. Case definition and enrollment were the same in the two studies, but control selection differed. In the first study, we selected two age- and sex-matched controls from inpatient subjects in hospitals, while for the second we selected two age- and sex-matched controls from each subject's neighborhood of residence. We used the test of heterogeneity to compare the results of the two studies. We found no significant differences in exposure data for tobacco-related variables such as cigarette smoking, chewing Nass (a tobacco product) and hookah (water pipe) usage, but the frequency of opium usage was significantly different between hospital and neighborhood controls. Consequently, the inference drawn for the association between ESCC and tobacco use did not differ between the studies, but it did for opium use. In the study using neighborhood controls, opium use was associated with a significantly increased risk of ESCC (adjusted OR 1.77, 95% CI 1.17–2.68), while in the study using hospital controls, this was not the case (OR 1.09, 95% CI 0.63–1.87). Comparing the prevalence of opium consumption in the two control groups and a cohort enrolled from the same geographic area suggested that the neighborhood controls were more representative of the study base population for this exposure.
Hospital and neighborhood controls did not lead us to the same conclusion for a major hypothesized risk factor for ESCC in this population. Our results show that control group selection is critical in drawing appropriate conclusions in observational studies.
PMCID: PMC3291619  PMID: 22396792
15.  Opium use and mortality in Golestan Cohort Study: prospective cohort study of 50 000 adults in Iran 
Objectives To investigate the association between opium use and subsequent risk of death.
Design Prospective cohort study.
Setting The Golestan Cohort Study in north-eastern Iran collected detailed validated data on opium use and other exposures at baseline. Participants were enrolled between January 2004 and June 2008 and were followed to May 2011, with a follow-up success rate of over 99%.
Participants 50 045 participants aged 40-75 at baseline.
Main outcomes Mortality, all cause and major subcategories.
Results 17% (n=8487) of the participants reported opium use, with a mean duration of 12.7 years. During the follow-up period 2145 deaths were reported. The adjusted hazard ratio for all cause mortality associated with ever use of opium was 1.86 (95% confidence interval 1.68 to 2.06). Opium consumption was significantly associated with increased risks of deaths from several causes including circulatory diseases (hazard ratio 1.81) and cancer (1.61). The strongest associations were seen with deaths from asthma, tuberculosis, and chronic obstructive pulmonary disease (11.0, 6.22, and 5.44, respectively). After exclusion of people who self prescribed opium after the onset of major chronic illnesses, the associations remained strong with a dose-response relation.
Conclusion Opium users have an increased risk of death from multiple causes compared with non-users. Increased risks were also seen in people who used low amounts of opium for a long period and those who had no major illness before use.
PMCID: PMC3328545  PMID: 22511302

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