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ABSTRACT: Identifying associations of risk factors sharing the same pathway with disease risk is complicated by small individual effects and intercorrelated components; this can be addressed by creating comprehensive exposure scores. We developed and validated 3 novel weighting methods (literature review-derived, study data-based, and a Bayesian method that combines prior knowledge with study data) to incorporate components into a pathway score for oxidative balance in addition to a commonly used method that assumes all components contribute equally to the score. We illustrate our method using pooled data from 3 US case-control studies of sporadic colorectal adenoma (1991-2002). We created 4 oxidative balance scores (OBS) to reflect combined summary measures of dietary and nondietary antioxidant and prooxidant exposures. A higher score represents a predominance of antioxidant exposures over prooxidant exposures. In the pooled data, the odds ratios comparing the highest tertile of OBS with the lowest for adenoma risk ranged from 0.38 to 0.54 for the 4 measures; all were statistically significant. These findings suggest that 1) OBS are indicators of oxidative balance and may be inversely associated with colorectal adenoma risk and 2) using comprehensive exposure scores may be preferable to investigating individual component-disease associations for complex exposures, such as oxidative balance.
American journal of epidemiology 05/2013; · 5.59 Impact Factor
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ABSTRACT: The United States Environmental Protection Agency and other regulatory agencies around the world have registered glyphosate as a broad-spectrum herbicide for use on multiple food and non-food use crops. Glyphosate is widely considered by regulatory authorities and scientific bodies to have no carcinogenic potential, based primarily on results of carcinogenicity studies of rats and mice. To examine potential cancer risks in humans, we reviewed the epidemiologic literature to evaluate whether exposure to glyphosate is associated causally with cancer risk in humans. We also reviewed relevant methodological and biomonitoring studies of glyphosate. Seven cohort studies and fourteen case-control studies examined the association between glyphosate and one or more cancer outcomes. Our review found no consistent pattern of positive associations indicating a causal relationship between total cancer (in adults or children) or any site-specific cancer and exposure to glyphosate. Data from biomonitoring studies underscore the importance of exposure assessment in epidemiologic studies, and indicate that studies should incorporate not only duration and frequency of pesticide use, but also type of pesticide formulation. Because generic exposure assessments likely lead to exposure misclassification, it is recommended that exposure algorithms be validated with biomonitoring data.
Regulatory Toxicology and Pharmacology 06/2012; 63(3):440-52. · 2.43 Impact Factor
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ABSTRACT: To systematically evaluate epidemiologic studies on pesticides and colon cancer and rectal cancer in agricultural pesticide applicator populations using a transparent "weight-of-evidence" (WOE) methodological approach.
Twenty-nine (29) publications from the Agricultural Health Study (AHS) and 13 additional epidemiologic studies were identified that reported data for pesticide applicators and/or specific pesticide compounds and colorectal, colon, or rectal cancer. The AHS evaluated pesticide applicators as well as dose-response associations for specific pesticide compounds, whereas the large majority of non-AHS evaluated applicators but did not analyze specific compounds or dose-response trends. This WOE assessment of 153 different pesticide-outcome pairs emphasized several key evidentiary features: existence of statistically significant relative risks, magnitude of observed associations, results from the most reliable exposure assessments, and evidence of convincing dose-response relationships (i.e., those monotonically increasing, with statistically significant trend tests).
Occupation as a pesticide applicator or pesticide application as a farming-related function was not associated with increasing the risk of colon or rectal cancer. Deficits of colon or rectal cancer were observed across most studies of pesticide applicators. After applying the WOE methodology to the epidemiologic studies of specific pesticide compounds and colon or rectal cancer, a number of pesticide-outcome pairs were identified and evaluated further based on positive statistical associations. Of these, only two-aldicarb and colon cancer and imazethapyr and proximal colon cancer-appears to warrant further discussion regarding a possible causal relationship, although the epidemiologic data are limited. For the remainder, a lack of a clear dose-response trend, inconsistencies in associations between exposure metrics and comparison groups, imprecise associations, variable participation rates for analyses of specific compounds, and the reliance upon data from one study (the AHS) limit interpretation regarding risk.
The available epidemiologic evidence does not support a causal relationship between occupation as a pesticide applicator or specific pesticide exposures and colon or rectal cancer.
Archiv für Gewerbepathologie und Gewerbehygiene 12/2011; 85(7):715-45. · 1.89 Impact Factor
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ABSTRACT: Medical and public health decisions are informed by reviews, which makes the quality of reviews an important scientific concern.
We systematically assessed the quality of published reviews on sugar-sweetened beverages (SSBs) and health, which is a controversial topic that is important to public health.
We performed a search of PubMed and Cochrane databases and a hand search of reference lists. Studies that were selected were published reviews and meta-analyses (June 2001 to June 2011) of epidemiologic studies of the relation between SSBs and obesity, type 2 diabetes, metabolic syndrome, and coronary heart disease. A standardized data-abstraction form was used. Review quality was assessed by using the validated instrument AMSTAR (assessment of multiple systematic reviews), which is a one-page tool with 11 questions.
Seventeen reviews met our inclusion and exclusion criteria: obesity or weight (16 reviews), diabetes (3 reviews), metabolic syndrome (3 reviews), and coronary heart disease (2 reviews). Authors frequently used a strictly narrative review (7 of 17 reviews). Only 6 of 17 reviews reported quantitative data in a table format. Overall, reviews of SSBs and health outcomes received moderately low-quality scores by the AMSTAR [mean: 4.4 points; median: 4 points; range: 1-8.5 points (out of a possible score of 11 points)]. AMSTAR scores were not related to the conclusions of authors (8 reviews reported an association with a mean AMSTAR score of 4.1 points; 9 reviews with equivocal conclusions scored 4.7 points; P value = 0.84). Less than one-third of published reviews reported a comprehensive literature search, listed included and excluded studies, or used duplicate study selection and data abstraction.
The comprehensive reporting of epidemiologic evidence and use of systematic methodologies to interpret evidence were underused in published reviews on SSBs and health.
American Journal of Clinical Nutrition 09/2011; 94(5):1340-7. · 6.67 Impact Factor
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ABSTRACT: The United States (US) Environmental Protection Agency (EPA) and other regulatory agencies around the world have registered glyphosate as a broad-spectrum herbicide for use on multiple food and non-food use crops. To examine potential health risks in humans, we searched and reviewed the literature to evaluate whether exposure to glyphosate is associated causally with non-cancer health risks in humans. We also reviewed biomonitoring studies of glyphosate to allow for a more comprehensive discussion of issues related to exposure assessment and misclassification. Cohort, case-control and cross-sectional studies on glyphosate and non-cancer outcomes evaluated a variety of endpoints, including non-cancer respiratory conditions, diabetes, myocardial infarction, reproductive and developmental outcomes, rheumatoid arthritis, thyroid disease, and Parkinson's disease. Our review found no evidence of a consistent pattern of positive associations indicating a causal relationship between any disease and exposure to glyphosate. Most reported associations were weak and not significantly different from 1.0. Because accurate exposure measurement is crucial for valid results, it is recommended that pesticide-specific exposure algorithms be developed and validated.
Regulatory Toxicology and Pharmacology 07/2011; 61(2):172-84. · 2.43 Impact Factor
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ABSTRACT: To evaluate the relationship between egg consumption and CHD and stroke mortality using the Third National Health and Nutrition Examination Survey 1988-1994 (NHANES III) and follow-up survey.
A cross-sectional survey using a stratified, multi-stage probability sample was analysed, adjusting for survey design. Egg consumption was obtained from the FFQ and separated into categories of egg intake. Hazard ratios (HR) were calculated for CHD and stroke mortality using multivariate Cox regression models.
A health and nutrition survey conducted in the USA from 1988 to 1994 with follow-up through 31 December 2000.
The study population included men and women who were free of CVD and had completed a FFQ at baseline.
Multivariate models adjusting for health, lifestyle and dietary factors indicated that 'high' egg consumption (≥ 7 times/week v. <1 time/week) was not associated with significantly increased CHD mortality (HR = 1·13, 95 % CI 0·61, 2·11 (men); HR = 0·92, 95 % CI 0·27, 3·11 (women)). There was a statistically significant inverse association between 'high' egg consumption and stroke mortality among men (HR = 0·27, 95 % CI 0·10, 0·73), but the estimate was imprecise because of sparse data. We did not observe a statistically significant positive association between 'high' egg consumption and CHD or stroke mortality in analyses restricted to individuals with diabetes, but these analyses may be limited due to the small number of diabetics.
We did not find a significant positive association between egg consumption and increased risk of mortality from CHD or stroke in the US population. These results corroborate the findings of previous studies.
Public Health Nutrition 02/2011; 14(2):261-70. · 2.17 Impact Factor
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ABSTRACT: Survival following diagnosis of pediatric Ewing's sarcoma or osteosarcoma is increasing in the United States, but whether survival differs between patients who receive limb salvage surgery compared to amputation has not been evaluated in nationally representative, population-based data.
Multivariable-adjusted survival was calculated using Cox regression models among surgically treated pediatric (age <20) osteosarcoma and Ewing's sarcoma patients with bone cancer of the limbs or joints reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program during 1988-2007.
Over half (66.3%) of the 890 osteosarcoma patients underwent limb salvage surgery. Five-year overall survival among patients who received limb salvage was 72.7% for osteosarcoma patients and 71.8% for Ewing's sarcoma patients. Among patients who received amputation, 5-year survival was 60.1% for osteosarcoma and 63.1% for Ewing's sarcoma patients. After multivariable adjustment, the mortality was 35% greater for amputation vs limb salvage (HR=1.35, 95% CI: 1.05-1.75). Among 165 Ewing's sarcoma patients, 73.9% underwent limb salvage (vs amputation), and the adjusted mortality was higher for patients receiving amputation, although results were not statistically significant (HR=1.61, 95% CI: 0.80-3.21).
Limb salvage surgery (vs amputation) is associated with longer survival among pediatric patients with bone cancer of the limbs or joints. Patient and physician characteristics and the effectiveness of neoadjuvant therapy may play a role in surgery choice, but we were unable to control for these factors.
J Registry Manag 01/2011; 38(3):153-61.
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ABSTRACT: Multiple myeloma (MM) is the most common hematologic malignancy in blacks. Some prior studies suggest inferior survival in blacks; others suggest similar survival. Using the original 9 Surveillance, Epidemiology, and End Results registries, we conducted a large-scale population-based study including 5798 black and 28 939 white MM patients diagnosed 1973-2005, followed through 2006. Age-adjusted incidence rates, disease-specific survival, and relative survival rates were calculated by race, age, and time period of diagnosis. Mean age at diagnosis was 65.8 and 69.8 years for blacks and whites, respectively (P < .001). Incidence among blacks was m twice that among whites; this disparity was greater among patients < 50 years (P = .002). Over the entire study period, disease-specific and relative survival rates were higher in blacks than whites (P < .001). For whites, 5-year relative survival rates increased significantly 1973-1993 to 1994-1998 (26.3% to 30.8%; P < .001) and 1994-1998 to 1999-2005 (30.8% to 35.0%; P = .004). Survival improvements among blacks were smaller and nonsignificant (1973-1993 to 1999-2005: 31.0% to 34.1%; P = .07). We found (1) a younger age of onset among blacks; (2) better survival in blacks 1973-2005; and (3) significant survival improvement among whites over time, with smaller, nonsignificant change seen among blacks, possibly due to unequal access to and/or disparate responsiveness to novel therapies.
Blood 12/2010; 116(25):5501-6. · 9.90 Impact Factor
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ABSTRACT: The relationship between meat consumption and breast cancer has been the focus of several epidemiological investigations, yet there has been no clear scientific consensus as to whether red or processed meat intake increases the risk of breast cancer. We conducted a comprehensive meta-analysis incorporating data from several recently published prospective studies of red or processed meat intake and breast cancer. In the meta-analysis utilising data from the Pooling Project publication (includes data from eight cohorts) combined with data from nine studies published between 2004 and 2009 and one study published in 1996, the fixed-effect summary relative risk estimate (SRRE) for red meat intake (high v. low) and breast cancer was 1·02 (95 % CI 0·98, 1·07; P value for heterogeneity = 0·001) and the random-effects SRRE was 1·07 (95 % CI 0·98, 1·17). The SRRE for each 100 g increment of red meat was 1·04 (95 % CI 1·00, 1·07), based on a fixed-effects model, and 1·12 (95 % CI 1·03, 1·23) based on a random-effects model. No association was observed for each 100 g increment of red meat among premenopausal women (SRRE 1·01; 95 % CI 0·92, 1·11) but a statistically significant SRRE of 1·22 (95 % CI 1·04, 1·44) was observed among postmenopausal women using a random-effects model. However, the association for postmenopausal women was attenuated and non-significant when using a fixed-effects model (SRRE 1·03; 95 % CI 0·98, 1·08). The fixed- and random-effect SRRE for high (v. low) processed meat intake and breast cancer were 1·00 (95 % CI 0·98, 1·01; P value for heterogeneity = 0·005) and 1·08 (95 % CI 1·01, 1·16), respectively. The fixed- and random-effect SRRE for each 30 g increment of processed meat were 1·03 (95 % CI 1·00, 1·06) and 1·06 (95 % CI 0·99, 1·14), respectively. Overall, weak positive summary associations were observed across all meta-analysis models, with the majority being non-statistically significant. Heterogeneity was evident in most analyses, summary associations were sensitive to the choice of analytical model (fixed v. random effects), and publication bias appeared to have produced slightly elevated summary associations. On the basis of this quantitative assessment, red meat and processed meat intake does not appear to be independently associated with increasing the risk of breast cancer, although further investigations of potential effect modifiers, such as analyses by hormone receptor status, may provide valuable insight to potential patterns of associations.
Nutrition Research Reviews 12/2010; 23(2):349-65. · 4.84 Impact Factor
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ABSTRACT: Over the past decade, several large epidemiologic investigations of meat intake and prostate cancer have been published. Therefore, a meta-analysis of prospective studies was conducted to estimate potential associations between red or processed meat intake and prostate cancer. Fifteen studies of red meat and 11 studies of processed meat were included in the analyses. High vs. low intake and dose-response analyses were conducted using random effects models to generate summary relative risk estimates (SRRE). No association between high vs. low red meat consumption (SRRE = 1.00, 95% CI: 0.96-1.05) or each 100 g increment of red meat (SRRE = 1.00, 95% CI: 0.95-1.05) and total prostate cancer was observed. Similarly, no association with red meat was observed for advanced prostate cancer (SRRE = 1.01, 95% CI: 0.94-1.09). A weakly elevated summary association between processed meat and total prostate cancer was found (SRRE = 1.05, 95% CI: 0.99-1.12), although heterogeneity was present, the association was attenuated in a sub-group analysis of studies that adjusted for multiple potential confounding factors, and publication bias likely affected the summary effect. In conclusion, the results of this meta-analysis are not supportive of an independent positive association between red or processed meat intake and prostate cancer.
Nutrition Journal 11/2010; 9:50. · 2.48 Impact Factor
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Human and Ecological Risk Assessment 08/2010; October 2004(Vol. 10):923-938. · 1.54 Impact Factor
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ABSTRACT: The objective of the present review was to examine the potential association between animal fat intake and breast cancer. We conducted a meta-analysis and review of epidemiological cohort studies, including data reported in the Pooling Project publication of Prospective Studies of Diet and Cancer. Random- and fixed-effects models were utilised to generate summary relative risk estimates (SRRE), and sensitivity and influence analyses were conducted. In the meta-analysis that included data reported in the Pooling Project publication of prospective cohorts (n 8) and subsequent publications of cohort studies (n 3), no significant association was observed comparing the highest category of animal fat intake with the lowest (SRRE 1.03; 95 % CI: 0.76, 1.40). Similarly, no significant association between a 5 % increment of energy from animal fat intake and breast cancer (SRRE 1.02; 95 % CI 0.97, 1.07) was observed in the meta-analysis of these studies. In conclusion, the results of the present quantitative assessment are not supportive of a positive independent association between consumption of animal fat and breast cancer, although findings may be sensitive to the type of dietary instrument used in cohort studies.
Nutrition Research Reviews 02/2010; 23(1):169-79. · 4.84 Impact Factor
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ABSTRACT: We conducted a meta-analysis of occupational studies of trichloroethylene-exposed workers to evaluate patterns of associations by study design, exposure assessment methods, and occupational groups.
Estimates of summary relative risk (RR) were calculated using inverse-variance weighting methods. Cohort studies were classified as group I or group II, depending on quality of the study design and exposure assessment procedures. We conducted sensitivity analyses to examine sources of heterogeneity.
Across all studies meeting our inclusion criteria (n = 23), the summary RR was 1.42 (95% confidence interval = 1.17-1.77), with heterogeneity present (test for heterogeneity: P = 0.001). After removal of 3 outlier studies, the summary RR for the remaining studies was 1.24 (1.06-1.45 (test for heterogeneity: P = 0.616)). The summary RR for studies of workers who were identified as more likely exposed to trichloroethylene (group I studies) was 1.34 (1.06-1.68). With outlier studies removed, the group II summary RR estimates for the cohort studies was 0.88 (0.58-1.33) and for the case-control studies was 1.33 (1.02-1.73). The summary RR for studies that used biomarkers to classify exposure (n = 3) was 1.02 (0.59-1.77) and for studies of aerospace/aircraft workers (n = 7) was 1.14 (0.84-1.57).
Positive associations were observed across various study groups. However, considerations of unmeasured potential confounding, lack of quantitative exposure assessment and lack of exposure-response patterns limit epidemiologic insight into the role of trichloroethylene exposure and its potential causal association with kidney cancer.
Epidemiology (Cambridge, Mass.) 01/2010; 21(1):95-102. · 5.51 Impact Factor
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ABSTRACT: Occupational sprain and strain injuries are one of the most common types of nonfatal occupational injuries and a significant source of lost workdays. This study examines factors associated with severe work-related sprain/strain injuries to the back, shoulder, and knees.
A synthetic case-control study was performed (controls were selected from the same pool of utility workers as cases). Cases included all electric utility workers who had experienced a severe work-related sprain/strain injury to the back, knee, or shoulder. Primary controls were selected from all workers who had sustained a minor injury. Secondary controls were selected from employees with a minor sprain/strain injury to the back, knee, or shoulder. Multivariate logistic regression models were used to estimate odds ratios and 95% confidence intervals.
Workers 41 years and older were more likely to have experienced severe shoulder sprain/strain injuries [Age 41-50: OR = 3.62, 95% CI: 1.71-7.65; age 51 and older: OR = 4.49, 95% CI: 1.89-10.67] and severe back sprain/strain injuries [Age 41-50: OR = 1.70, 95% CI: 1.06-2.33; age 51 and older: OR = 1.5, 95% CI: 0.90-2.52]. Line workers and maintenance workers had an increased risk of serious sprain/strain injuries. Gender and day of week were not significantly associated with sprain/strain injuries.
Though this study is limited by available data, future studies may benefit from this preliminary examination of occupational and demographic characteristics associated with serious sprain/strain injuries among electric utility workers.
American Journal of Industrial Medicine 01/2009; 52(3):210-20. · 1.63 Impact Factor
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ABSTRACT: Mesothelioma rates are declining toward background levels, although estimates of the background rate have varied. We expanded upon earlier analyses and provided a data-based estimate of the background rate. We analyzed US male and female patterns for five age groups using the National Cancer Institute's Surveillance Epidemiology and End Results registry data from 1973 to 2002. Age-specific and age-adjusted incidence rates per 1 000 000 persons per year, standardized to the 2000 US population, were calculated for total, pleural, and peritoneal mesothelioma. We also calculated rates for persons who attained working age after the US Occupational Safety and Health Administration asbestos exposure limits took effect. Mesothelioma rates observed among young males and females varied little over time. We observed a decline and convergence of recent male and female rates in older age groups, except those who are between the age of 60 and above, for whom the 2002 male rate was approximately five times greater than that of females. As expected, rates were higher in major shipyard areas on the West coast. Rates for persons with little or no opportunity for occupational asbestos exposure were 1.15 (95% confidence interval: 0.90-1.45) for men and 0.94 (95% confidence interval: 0.87-1.24) for women. Mesothelioma is rare in younger age groups, and rates have been relatively stable and similar for both sexes. Rates continue to decline in older age groups, but remain high for males at 60 years or older. Rates among females at older ages suggest an impact of occupational exposure. The background rate for persons below age 50 is approximately one per million, independent of sex. Future data are needed to estimate this rate for older age groups.
European journal of cancer prevention: the official journal of the European Cancer Prevention Organisation (ECP) 12/2008; 17(6):525-34. · 2.21 Impact Factor
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ABSTRACT: Flavonoids, which are found in certain plant foods, are thought to lower cancer risk through their antioxidant, antiestrogenic and antiproliferative properties. We examined the association of intake of total flavonoids and 7 flavonoid subclasses with risk of lung, colorectal, breast, pancreatic and upper aerodigestive cancer among women in a large prospective cohort study. Study participants were 34,708 postmenopausal women in the Iowa Women's Health Study who completed a food frequency questionnaire and were followed for cancer occurrence from 1986 through 2004. Flavonoid intake was estimated from 3 databases developed by the USDA Nutrient Data Laboratory (NDL). Hazard ratios (HR) for cancer risk were calculated across total flavonoid and flavonoid subclass intake categories. Interactions between smoking history and flavonoid intake were also examined. After multivariable adjustment, lung cancer incidence was inversely associated with intakes of flavanones (HR = 0.68; 95% CI: 0.53-0.86, all results highest vs. lowest quintile) and proanthocyanidins (HR = 0.75; 95% CI: 0.57-0.97). Among current and past smokers, those with intakes in the highest quintile for flavanones (HR = 0.66; 95% CI: 0.50-0.86), and proanthocyanidins (HR = 0.66; 95% CI; 0.49-0.89) had significantly lower lung cancer incidence than those in the lowest quintile. Similar associations were not seen in never smokers. Isoflavone intake was inversely associated with overall cancer incidence (HR = 0.93, 95% CI: 0.86-1.00). This study provides further support for a beneficial effect of flavonoid intake on lung cancer risk, especially among current and past smokers.
International Journal of Cancer 09/2008; 123(3):664-71. · 5.44 Impact Factor
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ABSTRACT: An association of low plasma HDL-cholesterol with risk of breast cancer has been suggested by multiple studies; the evidence, however, is not conclusive. We examined the possible association of low HDL-cholesterol with incidence of breast cancer using data from the Atherosclerosis Risk in Communities Study (ARIC) cohort, a prospective study of a randomly selected sample of women and men from four U.S. communities.
Among 7,575 female members of the ARIC cohort, 359 cases of incident breast cancer were ascertained during the follow-up from 1987 through 2000.
In analysis adjusted for age, race, body mass index, smoking, and reproductive variables, we observed no association of low baseline HDL-cholesterol (<50mg/dL) with incident breast cancer in the total sample (hazard ratio [HR]=1.08 [95% confidence interval (CI), 0.84-1.40]) and a modest association (HR=1.67 [95% CI, 1.06-2.63]) among women who were premenopausal at baseline. No association was observed among women who were postmenopausal at baseline. Removal from analysis of the first 5 years of follow-up did not appreciably change the observed associations.
Results of our study suggest that low HDL-cholesterol among premenopausal women may be a marker of increased breast cancer risk.
Annals of epidemiology 09/2008; 18(9):671-7. · 2.95 Impact Factor
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ABSTRACT: Although exposure to high levels of arsenic in drinking water is associated with excess cancer risk (e.g., skin, bladder, and lung), lower exposures (e.g., <100-200 microg/L) generally are not. Lack of significant associations at lower exposures may be attributed to methodologic issues (e.g., inadequate statistical power, exposure misclassification), or to differences in the dose-response relationship at high versus low exposures. The objectives of this review and meta-analysis were to evaluate associations, examine heterogeneity across studies, address study design and sample size issues, and improve the precision of estimates. Eight studies of bladder cancer and low-level arsenic exposure met our inclusion criteria. Meta-analyses of never smokers produced summary relative risk estimates (SRREs) below 1.0 (highest versus lowest exposure). The SRRE for never and ever smokers combined was elevated slightly, but not significantly (1.11; 95% CI: 0.95-1.30). The SRRE was somewhat elevated among ever smokers (1.24; 95% CI: 0.99-1.56), and statistical significance was observed in some subgroup analyses; however, heterogeneity across studies was commonly present. Although uncertainties remain, low-level arsenic exposure alone did not appear to be a significant independent risk factor for bladder cancer. More studies with detailed smoking history will help resolve whether smoking is an effect modifier.
Regulatory Toxicology and Pharmacology 09/2008; 52(3):299-310. · 2.43 Impact Factor
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ABSTRACT: Prostate cancer is the most commonly diagnosed cancer in US men, and the second most commonly diagnosed cancer among men worldwide. Although pesticides have been implicated in studies of prostate cancer among farmers, meta-analyses have found heterogeneity across studies, and a number of exposures and lifestyle factors may be unique to farmers. The purpose of this paper is to review the epidemiologic literature to evaluate the hypothesis that agricultural exposure to pesticides is causally associated with prostate cancer risk. We analyzed the eight cohort studies and five case-control studies that quantified and/or evaluated agricultural exposure to particular pesticide classes or chemicals. Despite sporadic positive findings, these studies did not show consistently increased risks to support a causal association between agricultural pesticide use and prostate cancer. Studies using an 'external' comparison group must be interpreted in the context of confounding by differences in prostate-specific antigen screening intensity. Furthermore, most studies did not adjust for potential confounders other than age and time period. It is clearly not possible to exonerate any particular pesticide as a putative cause of prostate cancer - to do so would require an inverse empirical association with an upper confidence limit below the null value. Existing evidence does not point to any pesticide as satisfying widely used guidelines for establishing causation: a strong, exposure-dependent and demonstrably unconfounded, unbiased association, documented in several studies.
European journal of cancer prevention: the official journal of the European Cancer Prevention Organisation (ECP) 05/2008; 17(2):97-110. · 2.21 Impact Factor
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ABSTRACT: Findings from epidemiologic studies of trichloroethylene (TCE) exposure and liver cancer have been inconsistent. To quantitatively evaluate this association and to examine sources of heterogeneity, we conducted a meta-analysis of occupational studies of TCE exposure and liver/biliary tract cancer.
We identified 14 occupational cohort studies of TCE exposed workers and one case-control study that met our inclusion criteria. Nine studies specifically identified TCE as a workplace exposure, and were classified as Group I cohort studies. Subcohorts of workers, identified within eight of these studies as more likely exposed to TCE than the total cohort, were analyzed separately.
The combined liver/biliary cancer summary relative risk estimate (SRRE) for all studies was 1.08 (95% CI 0.91-1.29; heterogeneity (H)-P-value=0.12). For the total study populations in the Group I cohorts, the SRRE was 1.14 (95% CI 0.93-1.39; H-P-value=0.05) and for the subcohorts, the SRRE was 1.30 (95% CI 1.09-1.55). Within this subcohort analysis, the association for the European studies of workers from various industries (SRRE=1.38; based on four studies) was higher than the association for the US studies of aerospace and aircraft workers (SRRE=0.97, based on four studies).
Although positive associations were observed for some analyses, results were inconsistent across occupational groups (aerospace/aircraft vs. other industries combined), study location, and incidence versus mortality endpoints. In addition, exposure-response trends were not observed consistently across studies. Interpretation is also limited by the potential impact of uncontrolled confounding by other occupational or lifestyle exposures such as smoking or alcohol consumption. Given these limitations, the currently available epidemiologic data are not sufficient to support a causal relation between occupational TCE exposure and liver/biliary cancer.
Archiv für Gewerbepathologie und Gewerbehygiene 12/2007; 81(2):127-43. · 1.89 Impact Factor
