Dataset Information

Is the inverse association between selenium and bladder cancer due to confounding by smoking?

ABSTRACT: Selenium has been linked to a reduced risk of bladder cancer in some studies. Smoking, a well-established risk factor for bladder cancer, has been associated with lower selenium levels in the body. We investigated the selenium-bladder cancer association in subjects from Maine, New Hampshire, and Vermont in the New England Bladder Cancer Case-Control Study. At interview (2001-2005), participants provided information on a variety of factors, including a comprehensive smoking history, and submitted toenail samples, from which we measured selenium levels. We estimated odds ratios and 95% confidence intervals among 1,058 cases and 1,271 controls using logistic regression. After controlling for smoking, we saw no evidence of an association between selenium levels and bladder cancer (for fourth quartile vs. first quartile, odds ratio (OR) = 0.98, 95% confidence interval (CI): 0.77, 1.25). When results were restricted to regular smokers, there appeared to be an inverse association (OR = 0.76, 95% CI: 0.58, 0.99); however, when pack-years of smoking were considered, this association was attenuated (OR = 0.91, 95% CI: 0.68, 1.20), indicating potential confounding by smoking. Despite some reports of an inverse association between selenium and bladder cancer overall, our results, combined with an in-depth evaluation of other studies, suggested that confounding from smoking intensity or duration could explain this association. Our study highlights the need to carefully evaluate the confounding association of smoking in the selenium-bladder cancer association.

SUBMITTER: Beane Freeman LE

PROVIDER: S-EPMC4447815 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Is the inverse association between selenium and bladder cancer due to confounding by smoking?

Beane Freeman Laura E LE Karagas Margaret R MR Baris Dalsu D Schwenn Molly M Johnson Alison T AT Colt Joanne S JS Jackson Brian B Hosain G M Monawar GM Cantor Kenneth P KP Silverman Debra T DT

American journal of epidemiology 20150315 7

Selenium has been linked to a reduced risk of bladder cancer in some studies. Smoking, a well-established risk factor for bladder cancer, has been associated with lower selenium levels in the body. We investigated the selenium-bladder cancer association in subjects from Maine, New Hampshire, and Vermont in the New England Bladder Cancer Case-Control Study. At interview (2001-2005), participants provided information on a variety of factors, including a comprehensive smoking history, and submitted ...[more]

PMID: 25776013

Similar Datasets

Project description:CONTEXT:Previous studies indicate that the population attributable risk (PAR) of bladder cancer for tobacco smoking is 50% to 65% in men and 20% to 30% in women and that current cigarette smoking triples bladder cancer risk relative to never smoking. During the last 30 years, incidence rates have remained stable in the United States in men (123.8 per 100,000 person-years to 142.2 per 100,000 person-years) and women (32.5 per 100,000 person-years to 33.2 per 100,000 person-years); however, changing smoking prevalence and cigarette composition warrant revisiting risk estimates for smoking and bladder cancer. OBJECTIVE:To evaluate the association between tobacco smoking and bladder cancer. DESIGN, SETTING, AND PARTICIPANTS:Men (n = 281,394) and women (n = 186,134) of the National Institutes of Health-AARP (NIH-AARP) Diet and Health Study cohort completed a lifestyle questionnaire and were followed up between October 25, 1995, and December 31, 2006. Previous prospective cohort studies of smoking and incident bladder cancer were identified by systematic review and relative risks were estimated from fixed-effects models with heterogeneity assessed by the I(2) statistic. MAIN OUTCOME MEASURES:Hazard ratios (HRs), PARs, and number needed to harm (NNH). RESULTS:During 4,518,941 person-years of follow-up, incident bladder cancer occurred in 3896 men (144.0 per 100,000 person-years) and 627 women (34.5 per 100,000 person-years). Former smokers (119.8 per 100,000 person-years; HR, 2.22; 95% confidence interval [CI], 2.03-2.44; NNH, 1250) and current smokers (177.3 per 100,000 person-years; HR, 4.06; 95% CI, 3.66-4.50; NNH, 727) had higher risks of bladder cancer than never smokers (39.8 per 100,000 person-years). In contrast, the summary risk estimate for current smoking in 7 previous studies (initiated between 1963 and 1987) was 2.94 (95% CI, 2.45-3.54; I(2) = 0.0%). The PAR for ever smoking in our study was 0.50 (95% CI, 0.45-0.54) in men and 0.52 (95% CI, 0.45-0.59) in women. CONCLUSION:Compared with a pooled estimate of US data from cohorts initiated between 1963 and 1987, relative risks for smoking in the more recent NIH-AARP Diet and Health Study cohort were higher, with PARs for women comparable with those for men.

Project description:Evidence supports no link between maternal smoking in pregnancy and autism spectrum disorder (autism) overall. To address remaining questions about the unexplained heterogeneity between study results and the possibility of risk for specific autism sub-phenotypes, we conducted a whole-population cohort study in Denmark. We followed births 1991-2011 (1,294,906 persons, including 993,301 siblings in 728,271 families), from 1 year of age until an autism diagnosis (13,547), death, emigration, or December 31, 2012. Autism, with and without attention deficit hyperactivity disorder (ADHD) and with and without intellectual disability (ID) were based on ICD-8 and ICD-10 codes from Danish national health registers, including 3,319 autism + ADHD, 10,228 autism - no ADHD, 2,205 autism + ID, and 11,342 autism - no ID. We estimated hazard ratios (HRs) and 95% confidence intervals (95% CIs) between any maternal smoking (from birth records) and autism (or sub-phenotypes) using survival models with robust standard errors, stratifying by birth year and adjusting for child sex, parity, and parental age, education, income, and psychiatric history. To additionally address confounding using family designs, we constructed a maternal cluster model (adjusting for the smoking proportion within the family), and a stratified sibling model. Associations with maternal smoking and autism were elevated in conventional adjusted analyses (HR of 1.17 [1.13-1.22]) but attenuated in the maternal cluster (0.98 [0.88-1.09]) and sibling (0.86 [0.64-1.15]) models. Similarly, risks of autism sub-phenotypes with maternal smoking were attenuated in the family-based models. Together these results support that smoking in pregnancy is not linked with autism or select autism comorbid sub-phenotypes after accounting for familial confounding. Autism Res 2020, 13: 134-144. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Smoking during pregnancy has many harmful impacts, which may include harming the baby's developing brain. However, in a study of thousands of families in Denmark, it does not appear that smoking in pregnancy leads to autism or autism in combination with intellectual problems or attention deficits, once you account for the way smoking patterns and developmental disabilities run in families.

Project description:While selenium is a cofactor of several antioxidant enzymes against cancer and is essential for human health, its excess intake may also be harmful. Though a safe intake of selenium has recently been recommended, it is not well understood in the Asian population. We aimed to determine the association between dietary intake of selenium and cancer risk in a case-control study of 3758 incident cancer cases (i.e., stomach, colon, rectum, lung cancers, and other sites) and 2929 control subjects in Vietnam. Daily intake of selenium was derived from a semiquantitative food frequency questionnaire. The unconditional logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the association between selenium intake and cancer risk. We observed a U-shaped association between selenium intake and cancer risk. A safe intake ranged from 110.8 to 124.4 µg/day (mean 117.8 µg/day). Compared to individuals with the safe intake of selenium, individuals with the lowest intake (i.e., 27.8-77.2 µg/day) were associated with an increased risk of cancer (OR = 3.78, 95% CI 2.89-4.95) and those with the highest intake (169.1-331.7 µg/day) also had an increased cancer risk (OR = 1.86, 95% CI 1.45-2.39). A U-shaped pattern of association between selenium intake and cancer risk was stronger among participants with body mass index (BMI) < 23 kg/m2 and never smokers than BMI ≥ 23 kg/m2 and ever smokers (P'sheterogeneity = 0.003 and 0.021, respectively) but found in both never and ever-drinkers of alcohol (Pheterogeneity = 0.001). A U-shaped association between selenium intake and cancer risk was seen in cancer sites of the stomach, colon, rectum, and lung cancers. In summary, we found a U-shaped association between selenium intake and cancer risk and a safe selenium intake (mean: 117.8 µg/day) in the Vietnamese population. Further mechanistic investigation is warranted to understand better a U-shaped association between selenium intake and cancer risk.

Dataset Information

Is the inverse association between selenium and bladder cancer due to confounding by smoking?

Publications

Is the inverse association between selenium and bladder cancer due to confounding by smoking?

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets