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1.  A genome-wide association study of marginal zone lymphoma shows association to the HLA region 
Vijai, Joseph | Wang, Zhaoming | Berndt, Sonja I. | Skibola, Christine F. | Slager, Susan L. | de Sanjose, Silvia | Melbye, Mads | Glimelius, Bengt | Bracci, Paige M. | Conde, Lucia | Birmann, Brenda M. | Wang, Sophia S. | Brooks-Wilson, Angela R. | Lan, Qing | de Bakker, Paul I. W. | Vermeulen, Roel C. H. | Portlock, Carol | Ansell, Stephen M. | Link, Brian K. | Riby, Jacques | North, Kari E. | Gu, Jian | Hjalgrim, Henrik | Cozen, Wendy | Becker, Nikolaus | Teras, Lauren R. | Spinelli, John J. | Turner, Jenny | Zhang, Yawei | Purdue, Mark P. | Giles, Graham G. | Kelly, Rachel S. | Zeleniuch-Jacquotte, Anne | Ennas, Maria Grazia | Monnereau, Alain | Bertrand, Kimberly A. | Albanes, Demetrius | Lightfoot, Tracy | Yeager, Meredith | Chung, Charles C. | Burdett, Laurie | Hutchinson, Amy | Lawrence, Charles | Montalvan, Rebecca | Liang, Liming | Huang, Jinyan | Ma, Baoshan | Villano, Danylo J. | Maria, Ann | Corines, Marina | Thomas, Tinu | Novak, Anne J. | Dogan, Ahmet | Liebow, Mark | Thompson, Carrie A. | Witzig, Thomas E. | Habermann, Thomas M. | Weiner, George J. | Smith, Martyn T. | Holly, Elizabeth A. | Jackson, Rebecca D. | Tinker, Lesley F. | Ye, Yuanqing | Adami, Hans-Olov | Smedby, Karin E. | De Roos, Anneclaire J. | Hartge, Patricia | Morton, Lindsay M. | Severson, Richard K. | Benavente, Yolanda | Boffetta, Paolo | Brennan, Paul | Foretova, Lenka | Maynadie, Marc | McKay, James | Staines, Anthony | Diver, W. Ryan | Vajdic, Claire M. | Armstrong, Bruce K. | Kricker, Anne | Zheng, Tongzhang | Holford, Theodore R. | Severi, Gianluca | Vineis, Paolo | Ferri, Giovanni M. | Ricco, Rosalia | Miligi, Lucia | Clavel, Jacqueline | Giovannucci, Edward | Kraft, Peter | Virtamo, Jarmo | Smith, Alex | Kane, Eleanor | Roman, Eve | Chiu, Brian C. H. | Fraumeni, Joseph F. | Wu, Xifeng | Cerhan, James R. | Offit, Kenneth | Chanock, Stephen J. | Rothman, Nathaniel | Nieters, Alexandra
Nature Communications  2015;6:5751.
Marginal zone lymphoma (MZL) is the third most common subtype of B-cell non-Hodgkin lymphoma. Here we perform a two-stage GWAS of 1,281 MZL cases and 7,127 controls of European ancestry and identify two independent loci near BTNL2 (rs9461741, P=3.95 × 10−15) and HLA-B (rs2922994, P=2.43 × 10−9) in the HLA region significantly associated with MZL risk. This is the first evidence that genetic variation in the major histocompatibility complex influences MZL susceptibility.
Marginal zone lymphoma (MZL) is a common subtype of B-cell non-Hodgkin lymphoma. Here the authors carry out a two-stage genome-wide association study in over 8,000 Europeans and identify two new MZL risk loci at chromosome 6p, implicating the major histocompatibility complex in the disease for the first time.
doi:10.1038/ncomms6751
PMCID: PMC4287989  PMID: 25569183
2.  Cigarette Smoking Is Associated With an Increased Risk of Biochemical Disease Recurrence, Metastasis, Castration-Resistant Prostate Cancer, and Mortality After Radical Prostatectomy 
Cancer  2013;120(2):197-204.
BACKGROUND
The current study was conducted to analyze the association between cigarette smoking and metastasis (the primary outcome) as well as time to biochemical disease recurrence (BCR), metastasis, castration-resistant prostate cancer (CRPC), and prostate cancer-specific and overall mortality (secondary outcomes) after radical prostatectomy among men from the Shared Equal Access Regional Cancer Hospital cohort.
METHODS
A retrospective analysis was performed of 1450 subjects for whom smoking status was available from preoperative notes. Analysis of baseline characteristics by smoking status was performed using the chi-square and rank sum tests. The association between smoking status and time to the event was analyzed using Kaplan-Meier plots, the log-rank test, and Cox and competing risk models.
RESULTS
A total of 549 men (33%) men were active smokers and 1121 (67%) were nonsmokers at the time of surgery. Current smokers were younger and had a lower body mass index, higher prostate-specific antigen level, and more extracapsular extension and seminal vesicle invasion (all P <.05). A total of 509 patients, 26 patients, 30 patients, 18 patients, and 217 patients, respectively, experienced BCR, metastasis, CRPC, prostate cancer-related death, and any-cause death over a median follow-up of 62 months, 75 months, 61 months, 78 months, and 78 months, respectively. After adjusting for preoperative features, active smoking was found to be associated with an increased risk of BCR (hazards ratio [HR], 1.25; P =.024), metastasis (HR, 2.64; P =.026), CRPC (HR, 2.62; P =.021), and overall mortality (HR, 2.14; P <.001). Similar results were noted after further adjustment for postoperative features, with the exception of BCR (HR, 1.10; P =.335), metastasis (HR, 2.51; P =.044), CRPC (HR, 2.67; P =.015), and death (HR, 2.03; P <.001).
CONCLUSIONS
Among patients undergoing radical prostatectomy, cigarette smoking was associated with an increased risk of metastasis. In addition, smoking was associated with a higher risk of BCR, CRPC, and overall mortality. If confirmed, these data suggest that smoking is a modifiable risk factor in patients with aggressive prostate cancer.
doi:10.1002/cncr.28423
PMCID: PMC4149056  PMID: 24127391
disease-free survival; metastasis; mortality; prostate cancer; prostatectomy; prostate-specific antigen; smoking; tobacco
3.  Mortality and cancer in relation to ABO blood group phenotypes in the Golestan Cohort Study 
BMC Medicine  2015;13:8.
Background
A few studies have shown an association between blood group alleles and vascular disease, including atherosclerosis, which is thought to be due to the higher level of von Willebrand factor in these individuals and the association of blood group locus variants with plasma lipid levels. No large population-based study has explored this association with overall and cause-specific mortality.
Methods
We aimed to study the association between ABO blood groups and overall and cause-specific mortality in the Golestan Cohort Study. In this cohort, 50,045 people 40- to 70-years old were recruited between 2004 and 2008, and followed annually to capture all incident cancers and deaths due to any cause. We used Cox regression models adjusted for age, sex, smoking, socioeconomic status, ethnicity, place of residence, education and opium use.
Results
During a total of 346,708 person-years of follow-up (mean duration 6.9 years), 3,623 cohort participants died. Non-O blood groups were associated with significantly increased total mortality (hazard ratio (HR) = 1.09; 95% confidence interval (CI): 1.01 to 1.17) and cardiovascular disease mortality (HR = 1.15; 95% CI: 1.03 to 1.27). Blood group was not significantly associated with overall cancer mortality, but people with group A, group B, and all non-O blood groups combined had increased risk of incident gastric cancer. In a subgroup of cohort participants, we also showed higher plasma total cholesterol and low-density lipoprotein (LDL) in those with blood group A.
Conclusions
Non-O blood groups have an increased mortality, particularly due to cardiovascular diseases, which may be due to the effect of blood group alleles on blood biochemistry or their effect on von Willebrand factor and factor VIII levels.
Please see related commentary 10.1186/s12916-014-0250-y.
doi:10.1186/s12916-014-0237-8
PMCID: PMC4295491  PMID: 25592833
Blood group; ABO; Rh; Mortality; Cancer; Cardiovascular disease
4.  Screening for Complex Diseases and Personalized Health Care 
BioMed Research International  2015;2015:135931.
doi:10.1155/2015/135931
PMCID: PMC4310255  PMID: 25654083
5.  Aberrant Methylation of Hypermethylated-in-Cancer-1 and Exocyclic DNA Adducts in Tobacco Smokers 
Toxicological Sciences  2013;137(1):47-54.
Tobacco smoke has been shown to produce both DNA damage and epigenetic alterations. However, the potential role of DNA damage in generating epigenetic changes is largely underinvestigated in human studies. We examined the effects of smoking on the levels of DNA methylation in genes for tumor protein p53, cyclin-dependent kinase inhibitor2A, hypermethylated-in-cancer-1 (HIC1), interleukin-6, Long Interspersed Nuclear Element type1, and Alu retrotransposons in blood of 177 residents in Thailand using bisulfite-PCR andpyrosequencing. Then, we analyzed the relationship of this methylation with the oxidative DNA adduct, M1dG (a malondialdehyde adduct), measured by 32P-postlabeling. Multivariate statistical analyses showed that HIC1 methylation levels were significantly increased in smokers compared with nonsmokers (p ≤ .05). A dose response was observed, with the highest HIC1 methylation levels in smokers of ≥ 10 cigarettes/day relative to nonsmokers and intermediate values in smokers of 1–9 cigarettes/day (p for trend ≤ .001). No additional relationships were observed. We also evaluated correlations between M1dG and the methylation changes at each HIC1 CpG site individually. The levels of this adduct in smokers showed a significant linear correlation with methylation at one of the 3 CpGs evaluated in HIC1: hypermethylation at position 1904864340 was significantly correlated with the adduct M1dG (covariate-adjusted regression coefficient (β) = .224 ± .101 [SE], p ≤ .05). No other correlations were detected. Our study extends prior work by others associating hypermethylation of HIC1 with smoking; shows that a very specific hypermethylation event can arise from smoking; and encourages future studies that explore a possible role for M1dG in connecting smoking to this latter hypermethylation.
doi:10.1093/toxsci/kft241
PMCID: PMC3871933  PMID: 24154486
tobacco smoking; overall and site specific methylation; HIC1; oxidative DNA damage; M1dG.
6.  Maté drinking and esophageal squamous cell carcinoma in South America: pooled results from two large multi-center case-control studies 
Background
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.
Methods
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).
Results
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.
Conclusions
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.
Impact
Increased understanding of cancer risks with maté consumption enhances the understanding of the public health consequences given its purported health benefits.
doi:10.1158/1055-9965.EPI-13-0796
PMCID: PMC3947123  PMID: 24130226
7.  Association of marijuana smoking with oropharyngeal and oral tongue cancers: Pooled analysis from the INHANCE Consortium 
Background
The incidence of oropharyngeal and oral tongue cancers have increased over the last twenty years which parallels increased use of marijuana among individuals born after 1950.
Methods
Pooled analysis of individual-level data from nine case-control studies from the U.S. and Latin America in the INHANCE consortium. Self-reported information on marijuana smoking, demographic, and behavioral factors was obtained from 1,921 oropharyngeal cases, 356 oral tongue cases, and 7,639 controls.
Results
Compared with never marijuana smokers, ever marijuana smokers had an elevated risk of oropharyngeal (adjusted odds ratio [aOR]: 1.24; 95% confidence interval [CI]: 1.06, 1.47) and a reduced risk of oral tongue cancer (aOR: 0.47; 95% CI: 0.29, 0.75). The risk of oropharyngeal cancer remained elevated among never tobacco and alcohol users. The risk of oral tongue cancer decreased with increasing frequency (ptrend=0.005), duration (ptrend=0.002), and joint-years of marijuana use (ptrend=0.004), and was reduced among never users tobacco and alcohol users. Sensitivity analysis adjusting for potential confounding by HPV exposure attenuated the association of marijuana use with oropharyngeal cancer (aOR: 0.99; 95% CI: 0.71, 1.25), but had no effect on the oral tongue cancer association.
Conclusions
These results suggest that the association of marijuana use with Head and Neck Carcinoma may differ by tumor site.
Impact
The associations of marijuana use with oropharyngeal and oral tongue cancer are consistent with both possible pro- and anti-carcinogenic effects of cannabinoids. Additional work is needed to rule out various sources of bias, including residual confounding by HPV infection and misclassification of marijuana exposure.
doi:10.1158/1055-9965.EPI-13-0181
PMCID: PMC3947141  PMID: 24351902
marijuana; oropharynx; oral tongue; INHANCE; human papillomavirus
8.  Promotion of Cardiovascular Health in Preschool Children: 36-Month Cohort Follow-up 
The American journal of medicine  2013;126(12):1122-1126.
BACKGROUND
Educational interventions in preschool children could improve dietary behavior and physical activity, and prevent unhealthy body weights in low- and middle-income countries. Previously, we have reported the beneficial impact of an educational intervention in preschoolers in a 6-month trial. We now report extended results after 36 months.
METHODS
Evaluating the cohort of previously intervened children, baseline measurements were made in May 2009 in 14 preschool facilities in Usaquén (Bogotá, Colombia). Follow-up measurements were performed at 18 and 36 months. The primary outcome was the mean change in children’s knowledge and attitudes scores regarding healthy eating and living an active lifestyle, including habits scores related to physical activity. Secondary outcomes were the change over time of children’s nutritional status and the mean change in parent’s knowledge, attitudes, and habits.
RESULTS
We included 1216 children, 3–5 years of age, and 928 parents. After adjusting by sex and age of children, socioeconomic status, age of parents, and age and education level of teachers, we found a significant increase in mean knowledge, attitudes, and habits scores at 36 months, compared with baseline: 87.94 vs 76.15 (P <.001); 86.39 vs 57.03 (P <.001); and 66.29 vs 48.72 (P <.001), respectively. We observed a similar increase in knowledge and attitude scores in parents: 73.45 vs 70.01 (P <.001); and 78.08 vs 74.65 (P <.001). The proportion of eutrophic children increased from 62.1% at baseline to 75.0% at 36 months (P <.0001).
CONCLUSIONS
After 36 months, the educational intervention maintained a beneficial trend toward a healthy lifestyle in children and their parents.
doi:10.1016/j.amjmed.2013.06.021
PMCID: PMC4106297  PMID: 24262725
Cardiovascular disease (CVD); Global health; Health education; Noncommunicable disease (NCD); Preschool children
9.  Welding and Lung Cancer in a Pooled Analysis of Case-Control Studies 
American Journal of Epidemiology  2013;178(10):1513-1525.
Several epidemiologic studies have indicated an increased risk of lung cancer among welders. We used the SYNERGY project database to assess welding as a risk factor for developing lung cancer. The database includes data on 15,483 male lung cancer cases and 18,388 male controls from 16 studies in Europe, Canada, China, and New Zealand conducted between 1985 and 2010. Odds ratios and 95% confidence intervals between regular or occasional welding and lung cancer were estimated, with adjustment for smoking, age, study center, and employment in other occupations associated with lung cancer risk. Overall, 568 cases and 427 controls had ever worked as welders and had an odds ratio of developing lung cancer of 1.44 (95% confidence interval: 1.25, 1.67) with the odds ratio increasing for longer duration of welding. In never and light smokers, the odds ratio was 1.96 (95% confidence interval: 1.37, 2.79). The odds ratios were somewhat higher for squamous and small cell lung cancers than for adenocarcinoma. Another 1,994 cases and 1,930 controls had ever worked in occupations with occasional welding. Work in any of these occupations was associated with some elevation of risk, though not as much as observed in regular welders. Our findings lend further support to the hypothesis that welding is associated with an increased risk of lung cancer.
doi:10.1093/aje/kwt201
PMCID: PMC3888276  PMID: 24052544
case-control studies; lung cancer; occupational exposure; welding
10.  Inflammatory and metabolic biomarkers and risk of liver and biliary tract cancer 
Hepatology (Baltimore, Md.)  2014;60(3):858-871.
Obesity and associated metabolic disorders have been implicated in liver carcinogenesis; however, there are little data on the role of obesity-related biomarkers on liver cancer risk. We studied prospectively the association of inflammatory and metabolic biomarkers with risks of hepatocellular carcinoma (HCC), intrahepatic bile duct (IBD), and gallbladder and biliary tract cancers outside of the liver (GBTC) in a nested case-control study within the European Prospective Investigation into Cancer and Nutrition. Over an average of 7.7 years, 296 participants developed HCC (n = 125), GBTC (n = 137), or IBD (n = 34). Using risk-set sampling, controls were selected in a 2:1 ratio and matched for recruitment center, age, sex, fasting status, and time of blood collection. Baseline serum concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), C-peptide, total high-molecular-weight (HMW) adiponectin, leptin, fetuin-a, and glutamatdehydrogenase (GLDH) were measured, and incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. After adjustment for lifestyle factors, diabetes, hepatitis infection, and adiposity measures, higher concentrations of CRP, IL-6, C-peptide, and non-HMW adiponectin were associated with higher risk of HCC (IRR per doubling of concentrations = 1.22; 95% CI = 1.02-1.46; P = 0.03; 1.90; 95% CI = 1.30-2.77; P = 0.001; 2.25; 95% CI = 1.43-3.54; P = 0.0005; and 2.09; 95% CI = 1.19-3.67; P = 0.01, respectively). CRP was associated also with risk of GBTC (IRR = 1.22; 95% CI = 1.05-1.42; P = 0.01). GLDH was associated with risks of HCC (IRR = 1.62; 95% CI = 1.25-2.11; P = 0.0003) and IBD (IRR = 10.5; 95% CI = 2.20-50.90; P = 0.003). The continuous net reclassification index was 0.63 for CRP, IL-6, C-peptide, and non-HMW adiponectin and 0.46 for GLDH, indicating good predictive ability of these biomarkers. Conclusion: Elevated levels of biomarkers of inflammation and hyperinsulinemia are associated with a higher risk of HCC, independent of obesity and established liver cancer risk factors. (Hepatology 2014;60:858–871)
doi:10.1002/hep.27016
PMCID: PMC4231978  PMID: 24443059
11.  Lung Cancer Risk Among Hairdressers: A Pooled Analysis of Case-Control Studies Conducted Between 1985 and 2010 
American Journal of Epidemiology  2013;178(9):1355-1365.
Increased lung cancer risks among hairdressers were observed in large registry-based cohort studies from Scandinavia, but these studies could not adjust for smoking. Our objective was to evaluate the lung cancer risk among hairdressers while adjusting for smoking and other confounders in a pooled database of 16 case-control studies conducted in Europe, Canada, China, and New Zealand between 1985 and 2010 (the Pooled Analysis of Case-Control Studies on the Joint Effects of Occupational Carcinogens in the Development of Lung Cancer). Lifetime occupational and smoking information was collected through interviews with 19,369 cases of lung cancer and 23,674 matched population or hospital controls. Overall, 170 cases and 167 controls had ever worked as hairdresser or barber. The odds ratios for lung cancer in women were 1.65 (95% confidence interval (CI): 1.16, 2.35) without adjustment for smoking and 1.12 (95% CI: 0.75, 1.68) with adjustment for smoking; however, women employed before 1954 also experienced an increased lung cancer risk after adjustment for smoking (odds ratio = 2.66, 95% CI: 1.09, 6.47). The odds ratios in male hairdressers/barbers were generally not elevated, except for an increased odds ratio for adenocarcinoma in long-term barbers (odds ratio = 2.20, 95% CI: 1.02, 4.77). Our results suggest that the increased lung cancer risks among hairdressers are due to their smoking behavior; single elevated risk estimates should be interpreted with caution and need replication in other studies.
doi:10.1093/aje/kwt119
PMCID: PMC3813309  PMID: 24068200
case-control studies; hair bleaching agents; hair color; lung neoplasms; occupational exposure
12.  DataSHIELD: taking the analysis to the data, not the data to the analysis 
Background: Research in modern biomedicine and social science requires sample sizes so large that they can often only be achieved through a pooled co-analysis of data from several studies. But the pooling of information from individuals in a central database that may be queried by researchers raises important ethico-legal questions and can be controversial. In the UK this has been highlighted by recent debate and controversy relating to the UK’s proposed ‘care.data’ initiative, and these issues reflect important societal and professional concerns about privacy, confidentiality and intellectual property. DataSHIELD provides a novel technological solution that can circumvent some of the most basic challenges in facilitating the access of researchers and other healthcare professionals to individual-level data.
Methods: Commands are sent from a central analysis computer (AC) to several data computers (DCs) storing the data to be co-analysed. The data sets are analysed simultaneously but in parallel. The separate parallelized analyses are linked by non-disclosive summary statistics and commands transmitted back and forth between the DCs and the AC. This paper describes the technical implementation of DataSHIELD using a modified R statistical environment linked to an Opal database deployed behind the computer firewall of each DC. Analysis is controlled through a standard R environment at the AC.
Results: Based on this Opal/R implementation, DataSHIELD is currently used by the Healthy Obese Project and the Environmental Core Project (BioSHaRE-EU) for the federated analysis of 10 data sets across eight European countries, and this illustrates the opportunities and challenges presented by the DataSHIELD approach.
Conclusions: DataSHIELD facilitates important research in settings where: (i) a co-analysis of individual-level data from several studies is scientifically necessary but governance restrictions prohibit the release or sharing of some of the required data, and/or render data access unacceptably slow; (ii) a research group (e.g. in a developing nation) is particularly vulnerable to loss of intellectual property—the researchers want to fully share the information held in their data with national and international collaborators, but do not wish to hand over the physical data themselves; and (iii) a data set is to be included in an individual-level co-analysis but the physical size of the data precludes direct transfer to a new site for analysis.
doi:10.1093/ije/dyu188
PMCID: PMC4276062  PMID: 25261970
DataSHIELD; pooled analysis; ELSI; privacy; confidentiality; disclosure; distributed computing; intellectual property; bioinformatics
13.  Interaction between Cigarette Smoking and HBV or HCV Infection on the Risk of Liver Cancer: A Meta-Analysis 
Introduction
Chronic infection with HBV and HCV as well as cigarette smoking are established risk factors of hepatocellular carcinoma (HCC), but it is unclear whether an interaction exists between these factors in causing hepatocellular carcinogenesis. We conducted a meta-analysis to evaluate the interaction of HBV and HCV infection and cigarette smoking on the risk of HCC.
Methods
We systematically searched the PUBMED and the China National Knowledge Infrastructure (CNKI) databases. A total of 16 eligible publications were identified. Cigarette smoking, and chronic HBV and HCV infections were dichotomized into present or absent. Additive (S) and multiplicative interaction indexes (V) between smoking and each of the two infections and their 95% confidence intervals (95% CI) were calculated for each study and then combined in a meta-analysis.
Results
We found a more than additive interaction between HBV infection and cigarette smoking (S=1.44, 95% CI=1.00–2.06; 9 studies) and a more than multiplicative interaction (V=1.60, 95% CI=1.16–2.20; 6 studies) between HCV infection and cigarette smoking. No publication bias was detected.
Conclusion
Smoking appears to interact with both HBV and HCV in determining HCC risk. A pooled analysis of individual subject data, with appropriate adjustment with other risk factors is warranted to confirm these results.
Impact
Chronic carriers of HBV and HCV are suggested to avoid smoking.
doi:10.1158/1055-9965.EPI-09-1297
PMCID: PMC4170071  PMID: 20447919
Cigarette smoking; HBV; HCV; HCC; interaction
14.  Reproductive factors and risk of esophageal squamous cell carcinoma in northern Iran- A case-control study in a high risk area and literature review 
Background
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.
Methods
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).
Results
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.
Conclusion
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.
doi:10.1097/CEJ.0b013e32835c7f87
PMCID: PMC3731403  PMID: 23238586
case-control study; esophageal cancer; miscarriage; parity; reproductive; squamous cell carcinoma
15.  Cigarette, Cigar, and Pipe Smoking and the Risk of Head and Neck Cancers: Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium 
American Journal of Epidemiology  2013;178(5):679-690.
Cigar and pipe smoking are considered risk factors for head and neck cancers, but the magnitude of effect estimates for these products has been imprecisely estimated. By using pooled data from the International Head and Neck Cancer Epidemiology (INHANCE) Consortium (comprising 13,935 cases and 18,691 controls in 19 studies from 1981 to 2007), we applied hierarchical logistic regression to more precisely estimate odds ratios and 95% confidence intervals for cigarette, cigar, and pipe smoking separately, compared with reference groups of those who had never smoked each single product. Odds ratios for cigar and pipe smoking were stratified by ever cigarette smoking. We also considered effect estimates of smoking a single product exclusively versus never having smoked any product (reference group). Among never cigarette smokers, the odds ratio for ever cigar smoking was 2.54 (95% confidence interval (CI): 1.93, 3.34), and the odds ratio for ever pipe smoking was 2.08 (95% CI: 1.55, 2.81). These odds ratios increased with increasing frequency and duration of smoking (Ptrend ≤ 0.0001). Odds ratios for cigar and pipe smoking were not elevated among ever cigarette smokers. Head and neck cancer risk was elevated for those who reported exclusive cigar smoking (odds ratio = 3.49, 95% CI: 2.58, 4.73) or exclusive pipe smoking (odds ratio = 3.71, 95% CI: 2.59, 5.33). These results suggest that cigar and pipe smoking are independently associated with increased risk of head and neck cancers.
doi:10.1093/aje/kwt029
PMCID: PMC3755640  PMID: 23817919
head and neck neoplasms; smoking
16.  A Pooled Analysis of Alcohol Consumption and Risk of Multiple Myeloma in the International Multiple Myeloma Consortium 
Background
Recent findings suggest that alcohol consumption may reduce risk of multiple myeloma (MM).
Methods
To better understand this relationship, we conducted an analysis of six case-control studies participating in the International Multiple Myeloma Consortium (1,567 cases, 7,296 controls). Summary odds ratios (ORs) and 95% confidence intervals (CI) relating different measures of alcohol consumption and MM risk were computed by unconditional logistic regression with adjustment for age, race, and study center.
Results
Cases were significantly less likely than controls to report ever drinking alcohol (men: OR 0.72, 95% CI 0.59-0.89, women: OR 0.81, 0.68-0.95). The inverse association with MM was stronger when comparing current to never drinkers (men: OR=0.57, 95% CI 0.45-0.72, women: OR=0.55, 95% CI 0.45-0.68), but null among former drinkers. We did not observe an exposure-response relationship with increasing alcohol frequency, duration or cumulative lifetime consumption. Additional adjustment for body mass index, education, or smoking did not affect our results; and the patterns of association were similar for each type of alcohol beverage examined.
Conclusions
Our study is, to our knowledge, the largest of its kind to date, and our findings suggest that alcohol consumption may be associated with reduced risk of MM.
Impact
Prospective studies, especially those conducted as pooled analyses with large sample sizes, are needed to confirm our findings and further explore whether alcohol consumption provides true biologic protection against this rare, highly fatal malignancy.
doi:10.1158/1055-9965.EPI-13-0334
PMCID: PMC3769449  PMID: 23964064
18.  Can a genotype for lactase persistence be used as a tool to assess the relationship between renal cell carcinoma and milk drinking? Pitfalls in the application of Mendelian randomization 
Background
Increased risk of renal cell carcinoma (RCC) with milk consumption has been reported from observational studies including that involved here. Whether this represents causal association or whether it is the result of confounding or bias is unclear. We aimed to assess the potential for genetic variation in lactase persistence to be used as a tool for the interrogation of these relationships.
Methods
Using a large, hospital based case control study, we use a combination of observational genetic and phenotypic data to determine whether the MCM6 -13910 C/T(rs4988235) variant may be used as an non-confounded and unbiased marker for milk consumption.
Results
Consumption of milk during adulthood was associated with increased risk of RCC (OR=1.35 95% CI 1.03, 1.76 p=0.03). Among controls, consumption of milk was associated with the lactase persistence genotype at rs4988235 (2.39[1.81, 3.15], p=6.9*10−10), however the same genotype was not associated with RCC (OR=1.01 95% CI 0.83, 1.22 p=0.9). In controls, milk consumption was associated with confounding factors including smoking, and educational attainment, while the lactase persistence genotype at rs4988235 genotype showed negligible association with confounding factors.
Conclusions
The absence of an association between the MCM6 genotype and RCC suggests that observational associations between milk consumption and RCC may be due to confounding or bias. However, if the association between genotype and behavioral exposure is weak, then the power of this test may be low. The nature of intermediate risk factor instrumentation is an important consideration in the undertaking and interpretation of this type of causal analysis experiment.
doi:10.1158/1055-9965.EPI-09-1019
PMCID: PMC4141143  PMID: 20447925
Mendelian randomization; lactase persistence; renal carcinoma
19.  Adult height and head and neck cancer: a pooled analysis within the INHANCE Consortium 
Background
Several epidemiological studies have shown a positive association between adult height and cancer incidence. The only study conducted among women on mouth and pharynx cancer risk, however, reported an inverse association. This study aims to investigate the association between height and the risk of head and neck cancer (HNC) within a large international consortium of HNC.
Methods
We analyzed pooled individual-level data from 24 case-control studies participating in the International Head and Neck Cancer Epidemiology Consortium. Odds Ratios (ORs) and 95% Confidence Intervals (CIs) were estimated separately for men and women for associations between height and HNC risk. Educational level, tobacco smoking, and alcohol consumption were included in all regression models. Stratified analyses by HNC subsites were performed.
Results
This project included 17,666 cases and 28,198 controls. We found an inverse association between height and HNC (adjusted OR per 10 cm height =0.91, 95% CI 0.86–0.95 for men; adjusted OR=0.86, 95% CI 0.79–0.93 for women). In men, the estimated OR did vary by educational level, smoking status, geographic area, and control source. No differences by subsites were detected.
Conclusions
Adult height is inversely associated with HNC risk. As height can be considered a marker of childhood illness and low energy intake, the inverse association is consistent with prior studies showing that HNC occur more frequently among deprived individuals. Further studies designed to elucidate the mechanism of such association would be warranted.
doi:10.1007/s10654-013-9863-2
PMCID: PMC4122122  PMID: 24271556
20.  A critical review of the epidemiology of Agent Orange/TCDD and prostate cancer 
European Journal of Epidemiology  2014;29(10):667-723.
To inform risk assessment and regulatory decision-making, the relationship between 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and prostate cancer requires clarification. This article systematically and critically reviews the epidemiologic evidence on the association between exposure to TCDD or Agent Orange, a TCDD-contaminated herbicide used during the Vietnam War, and prostate cancer risk. Articles evaluated include 11 studies of three cohorts, four case–control or cross-sectional studies, and three case-only studies of military veterans with information on estimated Agent Orange or TCDD exposure; 13 studies of seven cohorts, one case–control study, and eight proportionate morbidity or mortality studies of Vietnam veterans without information on Agent Orange exposure; 11 cohort studies of workers with occupational exposure to TCDD; and two studies of one community cohort with environmental exposure to TCDD. The most informative studies, including those of Vietnam veterans involved in Agent Orange spraying or other handling, herbicide manufacturing or spraying workers with occupational TCDD exposure, and community members exposed to TCDD through an industrial accident, consistently reported no significant increase in prostate cancer incidence or mortality. Only some potentially confounded studies of Vietnam veterans compared with the general population, studies with unreliable estimates of Agent Orange exposure, and analyses of selected subgroups of Vietnam veterans reported positive associations. Overall, epidemiologic research offers no consistent or convincing evidence of a causal relationship between exposure to Agent Orange or TCDD and prostate cancer. More accurate exposure assessment is needed in large epidemiologic studies to rule out a causal association more conclusively.
Electronic supplementary material
The online version of this article (doi:10.1007/s10654-014-9931-2) contains supplementary material, which is available to authorized users.
doi:10.1007/s10654-014-9931-2
PMCID: PMC4197347  PMID: 25064616
Prostate cancer; TCDD; Dioxin; Agent Orange; Veterans; Epidemiology
21.  Opium; an emerging risk factor for gastric adenocarcinoma 
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.
doi:10.1002/ijc.28018
PMCID: PMC3644384  PMID: 23319416
Opium; Adenocarcinoma; Cardia
22.  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.
doi:10.1002/ijc.27953
PMCID: PMC3597757  PMID: 23175176
Polycyclic aromatic hydrocarbons; DNA adducts; nucleotide excision repair; polymorphism
23.  Attributable fraction of alcohol consumption on cancer using population-based nationwide cancer incidence and mortality data in the Republic of Korea 
BMC Cancer  2014;14:420.
Background
In the Republic of Korea, cancer is the most common cause of death, and cancer incidence and mortality rates are the highest in East Asia. As alcoholic beverages are carcinogenic to humans, we estimated the burden of cancer related to alcohol consumption in the Korean population.
Methods
The cancer sites studied were those for which there is convincing evidence of a positive association with alcohol consumption: oral cavity, pharynx, esophagus, colon, rectum, liver, larynx and female breast. Sex- and cancer-specific population attributable fractions (PAF) were calculated based on: 1) the prevalence of alcohol drinkers among adults ≥20 years of age in 1989; 2) the average daily alcohol consumption (g/day) among drinkers in 1998; 3) relative risk (RR) estimates for the association between alcohol consumption and site-specific cancer incidence obtained either from a large Korean cohort study or, when more than one Korean study was available for a specific cancer site, meta-analyses were performed and the resulting meta-RRs were used; 4) national cancer incidence and mortality data from 2009.
Results
Among men, 3% (2,866 cases) of incident cancer cases and 2.8% (1,234 deaths) of cancer deaths were attributable to alcohol consumption. Among women, 0.5% (464 cancer cases) of incident cancers and 0.1% (32 deaths) of cancer deaths were attributable to alcohol consumption. In particular, the PAF for alcohol consumption in relation to oral cavity cancer incidence among Korean men was 29.3%, and the PAFs for pharyngeal and laryngeal cancer incidence were 43.3% and 25.8%, respectively. Among Korean women, the PAF for colorectal cancer incidence was the highest (4.2%) and that for breast cancer incidence was only 0.2%. Avoiding alcohol consumption, or reducing it from the median of the highest 4th quartile of consumption (56.0 g/day for men, 28.0 g/day for women) to the median of the lowest quartile (2.80 g/day for men, 0.80 g/day for women), would reduce the burden of alcohol-related cancers in Korea.
Conclusions
A reduction in alcohol consumption would decrease the cancer burden and a significant impact is anticipated specifically for the cancers oral cavity, pharynx, and larynx among men in the Republic of Korea.
doi:10.1186/1471-2407-14-420
PMCID: PMC4065076  PMID: 24917392
Risk factor; Population attributable fraction; Lifestyle; Asia
24.  Attributable fraction of tobacco smoking on cancer using population-based nationwide cancer incidence and mortality data in Korea 
BMC Cancer  2014;14:406.
Background
Smoking is by far the most important cause of cancer that can be modified at the individual level. Cancer incidence and mortality rates in Korea are the highest among all Asian countries, and smoking prevalence in Korean men is one of the highest in developed countries. The purpose of the current study was to perform a systematic review and provide an evidence-based assessment of the burden of tobacco smoking-related cancers in the Korean population.
Methods
Sex- and cancer-specific population-attributable fractions (PAF) were estimated using the prevalence of ever-smoking and second-hand smoking in 1989 among Korean adults, respectively, and the relative risks were estimated from the meta-analysis of studies performed in the Korean population for ever-smoking and in the Asian population for passive smoking. National cancer incidence data from the Korea Central Cancer Registry and national cancer mortality data from Statistics Korea for the year 2009 were used to estimate the cancer cases and deaths attributable to tobacco smoking.
Results
Tobacco smoking was responsible for 20,239 (20.9%) cancer incident cases and 14,377 (32.9%) cancer deaths among adult men and 1,930 (2.1%) cancer incident cases and 1,351 (5.2%) cancer deaths among adult women in 2009 in Korea. In men, 71% of lung cancer deaths, 55%–72% of upper aerodigestive tract (oral cavity, pharynx, esophagus and larynx) cancer deaths, 23% of liver, 32% of stomach, 27% of pancreas, 7% of kidney and 45% of bladder cancer deaths were attributable to tobacco smoking. In women the proportion of ever-smoking-attributable lung cancer was 8.1%, while that attributable to second-hand smoking among non-smoking women was 20.5%.
Conclusions
Approximately one in three cancer deaths would be potentially preventable through appropriate control of tobacco smoking in Korean men at the population level and individual level. For Korean women, more lung cancer cases and deaths were attributable to second-hand than ever-smoking. Effective control programs against tobacco smoking should be further developed and implemented in Korea to reduce the smoking-related cancer burden.
doi:10.1186/1471-2407-14-406
PMCID: PMC4090397  PMID: 24902960
Risk factor; Population attributable fraction; Lifestyle; Asia
25.  An investigation of risk factors for renal cell carcinoma by histologic subtype in two case-control studies 
To investigate whether renal cell carcinoma (RCC) histologic subtypes possess different etiologies, we conducted analyses of established RCC risk factors by subtype (clear cell, papillary, chromophobe) in two case-control studies conducted in the United States (1,217 cases, 1,235 controls) and Europe (1,097 cases, 1,476 controls). Histology was ascertained for 706 U.S. cases (58% of total) and 917 European cases (84%) through a central slide review conducted by a single pathologist. For the remaining cases, histology was abstracted from the original diagnostic pathology report. Case-only analyses were performed to compute odds ratios (ORs) and 95% confidence intervals (CI) summarizing subtype differences by age, sex, and race. Case-control analyses were performed to compute subtype-specific ORs for other risk factors using polytomous regression. In case-only analyses, papillary cases (N=237) were older (OR=1.2, 95% CI=1.1–1.4 per 10-year increase), less likely to be female (OR=0.5, 95 % CI=0.4- 0.8) and more likely to be black (OR=2.6, 95% CI=1.8–3.9) compared to clear cell cases (N=1,524). In case-control analyses, BMI was associated with clear cell (OR=1.2, 95% CI=1.1–1.3 per 5kg/m2 increase) and chromophobe RCC (N=80; OR=1.2, 95% CI=1.1- 1.4), but not papillary RCC (OR=1.1, 95% CI=1.0–1.2; test vs. clear cell, P=0.006). No subtype differences were observed for associations with smoking, hypertension or family history of kidney cancer. Our findings support the existence of distinct age, sex and racial distributions for RCC subtypes, and suggest that the obesity-RCC association differs by histology.
doi:10.1002/ijc.27934
PMCID: PMC3717609  PMID: 23150424
Renal cell carcinoma; histology; case-control studies; body mass index

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