A hypothetical intervention to reduce inequities in anxiety for Multiracial people: simulating an intervention on childhood adversity.

Multiracial people report higher mean Adverse Childhood Experiences (ACEs) scores and prevalence of anxiety than other racial groups. Studies using statistical interactions to estimate racial differences in ACEs-anxiety associations do not show stronger associations for Multiracial people. Using data from Waves 1 (1995-97) through 4 (2008-09) of the National Longitudinal Study of Adolescent to Adult Health (Add Health), we simulated a stochastic intervention over 1,000 resampled datasets to estimate the race-specific cases averted per 1,000 of anxiety if all racial groups had the same exposure distribution of ACEs as Whites. Simulated cases averted were greatest for the Multiracial group, (median = -4.17 cases per 1,000, 95% CI: -7.42, -1.86). The model also predicted smaller risk reductions for Black participants (-0.76, 95% CI: -1.53, -0.19). CIs around estimates for other racial groups included the null. An intervention to reduce racial disparities in exposure to ACEs could help reduce the inequitable burden of anxiety on the Multiracial population. Stochastic methods support consequentialist approaches to racial health equity, and can encourage greater dialogue between public health researchers, policymakers, and practitioners.

Neighborhood-level Fatal Police Violence and Severe Maternal Morbidity in California.

Police violence is a pervasive issue that may have adverse implications for severe maternal morbidity (SMM). We assessed how the occurrence of fatal police violence (FPV) in one's neighborhood before/during pregnancy may influence SMM risk. Hospital discharge records from California between 2002-2018 were linked with the Fatal Encounters database (N=2,608,682). We identified 2,184 neighborhoods (census-tracts) with at least one FPV incident during the study period and used neighborhood fixed-effects models adjusting for individual sociodemographic characteristics to estimate odds of SMM associated with experiencing FPV in one's neighborhood anytime within the 24-months before childbirth. We did not find conclusive evidence on the link between FPV occurrence before delivery and SMM. However, estimates show that birthing people residing in neighborhoods where one or more FPV events had occurred within the preceding 24-months of giving birth may have a mildly elevated odds of SMM than those residing in the same neighborhoods with no FPV occurrence during the 24-months preceding childbirth (Odds Ratio (OR)=1.02; 95% Confidence Interval (CI): 0.99-1.05), particularly among those living in neighborhoods with fewer (1-2) FPV incidents throughout the study period (OR=1.03; 95% CI:1.00-1.06). Our findings provide evidence for the need to continue to examine the health consequences of police violence.

Body composition and cancer survival: a narrative review.

Interest in understanding the relationship between body composition and cancer survival has remained strong for decades, with a number of recent systematic reviews on the topic. However, the current state of evidence is based on heterogeneous exposure definitions based on anthropometry, yielding inconsistent findings with regard to this association. Recently the field has taken an exciting direction with the application of radiological assessments to measure specific aspects of body composition, yet reconciliation of findings from these modern assessment tools with those from the historic use of anthropometric data proves challenging. In this paper, I briefly review the biological basis for a link between body composition and cancer survival and summarize the epidemiological evidence with consideration to specific exposure measures. As enthusiasm is building around novel assessments, I conclude with a discussion of issues that researchers should be aware of when interpreting results from these new modalities.

The association between the Mediterranean Diet Score and death from cancer of the head and neck.

PURPOSE: The association between diet quality, captured by the Mediterranean Diet Score (MDS), and mortality was studied among 1184 individuals diagnosed with head and neck cancer (HNC) who reflected on the year preceding diagnosis about their usual diet using National Cancer Institute's Diet History Questionnaire (DHQ). METHODS: Intakes of nine dietary components were scored and summed to construct the MDS (sample: median = 4; range (0-9); lower MDS reflected poorer diet quality; 5-year survival probability = 0.62). Cox regression estimated 5-year hazard ratios (HR) and 95% confidence intervals (95CI) for all-cause mortality and for HNC-specific death for contrasts of MDS quintiles. Effect measure modification (EMM) by tumor features [human papillomavirus (HPV) positivity; anatomic site] and sociodemographic behavioral factors [race, body mass index (BMI), smoking, alcohol consumption] was explored. RESULTS: The 5-year [HR (95CI); P-trend] for all-cause mortality and HNC-specific mortality for highest versus lowest MDS quintile contrasts were [0.51 (0.33, 0.80); 0.014] and [0.43 (0.22, 0.85); 0.004], respectively. A unit increase in MDS adherence resulted in a 15% reduction of the 5-year HR for HNC-specific death for tumors located at the oral cavity [HR (95CI): 0.85 (0.75, 0.96)]. Poor diet quality (MDS ≤ 4) interacted with lower BMI (kg/m2 < 25) and separately with ever-using alcohol to produce 5-year HRs for all-cause and HNC-specific mortality that were statistically significantly larger than the sum of the individual HRs representing each combination (Poor diet quality + lower BMI; Poor diet quality + ever-using alcohol). CONCLUSION: Greater adherence to a Mediterranean diet pattern prior to HNC diagnosis may reduce post-diagnosis mortality.

Accounting for Misclassification and Selection Bias in Estimating Effectiveness of Self-managed Medication Abortion.

BACKGROUND: Studies on the effectiveness of self-managed medication abortion may suffer from misclassification and selection bias due to self-reported outcomes and loss of follow-up. Monte Carlo sensitivity analysis can estimate self-managed abortion effectiveness accounting for these potential biases. METHODS: We conducted a Monte Carlo sensitivity analysis based on data from the Studying Accompaniment model Feasibility and Effectiveness Study (the SAFE Study), to generate bias-adjusted estimates of the effectiveness of self-managed abortion with accompaniment group support. Between July 2019 and April 2020, we enrolled a total of 1051 callers who contacted accompaniment groups in Argentina and Nigeria for self-managed abortion information; 961 took abortion medications and completed at least one follow-up. Using these data, we calculated measures of effectiveness adjusted for ineligibility, misclassification, and selection bias across 50,000 simulations with bias parameters drawn from pre-specified Beta distributions in R. RESULTS: After accounting for the potential influence of various sources of bias, bias-adjusted estimates of effectiveness were similar to observed estimates, conditional on chosen bias parameters: 92.68% (95% simulation interval: 87.80%, 95.74%) for mifepristone in combination with misoprostol (versus 93.7% in the observed data) and 98.47% (95% simulation interval: 96.79%, 99.39%) for misoprostol alone (versus 99.3% in the observed data). CONCLUSIONS: After adjustment for multiple potential sources of bias, estimates of self-managed medication abortion effectiveness remain high. Monte Carlo sensitivity analysis may be useful in studies measuring an epidemiologic proportion (i.e., effectiveness, prevalence, cumulative incidence) while accounting for possible selection or misclassification bias.

Development and validation of prediction models for gestational diabetes treatment modality using supervised machine learning: a population-based cohort study.

BACKGROUND: Gestational diabetes (GDM) is prevalent and benefits from timely and effective treatment, given the short window to impact glycemic control. Clinicians face major barriers to choosing effectively among treatment modalities [medical nutrition therapy (MNT) with or without pharmacologic treatment (antidiabetic oral agents and/or insulin)]. We investigated whether clinical data at varied stages of pregnancy can predict GDM treatment modality. METHODS: Among a population-based cohort of 30,474 pregnancies with GDM delivered at Kaiser Permanente Northern California in 2007-2017, we selected those in 2007-2016 as the discovery set and 2017 as the temporal/future validation set. Potential predictors were extracted from electronic health records at different timepoints (levels 1-4): (1) 1-year preconception to the last menstrual period, (2) the last menstrual period to GDM diagnosis, (3) at GDM diagnosis, and (4) 1 week after GDM diagnosis. We compared transparent and ensemble machine learning prediction methods, including least absolute shrinkage and selection operator (LASSO) regression and super learner, containing classification and regression tree, LASSO regression, random forest, and extreme gradient boosting algorithms, to predict risks for pharmacologic treatment beyond MNT. RESULTS: The super learner using levels 1-4 predictors had higher predictability [tenfold cross-validated C-statistic in discovery/validation set: 0.934 (95% CI: 0.931-0.936)/0.815 (0.800-0.829)], compared to levels 1, 1-2, and 1-3 (discovery/validation set C-statistic: 0.683-0.869/0.634-0.754). A simpler, more interpretable model, including timing of GDM diagnosis, diagnostic fasting glucose value, and the status and frequency of glycemic control at fasting during one-week post diagnosis, was developed using tenfold cross-validated logistic regression based on super learner-selected predictors. This model compared to the super learner had only a modest reduction in predictability [discovery/validation set C-statistic: 0.825 (0.820-0.830)/0.798 (95% CI: 0.783-0.813)]. CONCLUSIONS: Clinical data demonstrated reasonably high predictability for GDM treatment modality at the time of GDM diagnosis and high predictability at 1-week post GDM diagnosis. These population-based, clinically oriented models may support algorithm-based risk-stratification for treatment modality, inform timely treatment, and catalyze more effective management of GDM.

Residential proximity to agricultural pesticide use and risk-taking behaviors in young adults from the CHAMACOS study.

BACKGROUND: Prenatal pesticide exposure has been associated with poorer neurodevelopment during childhood, which could lead to greater risk-taking behaviors and delinquency in adolescence. This association may be augmented by adversity exposure. OBJECTIVES: Evaluate the relationship between prenatal pesticide exposure and risk-taking behavior in young adults at 18-years of age. Assess whether adversity exposure modifies these associations. METHODS: Participants included mother-child dyads (n = 467) enrolled in the Center for the Health Assessment of Mothers and Children Of Salinas (CHAMACOS) study, a longitudinal birth cohort set in the agricultural Salinas Valley of California. We estimated agricultural pesticide use within one km of maternal residences during pregnancy using a geographic information system, residential addresses, and California's Pesticide Use Reporting data. We used Bayesian hierarchical regression to evaluate associations of prenatal exposure to a mixture of 11 neurotoxic pesticides with self-reported police encounters, risk-taking behaviors, and unique types and frequency of delinquent acts. We also evaluated effect modification of these relationships by adversity exposure. RESULTS: We observed generally null associations of neurotoxic pesticide use with risk-taking behaviors. Prenatal residential proximity to chlorpyrifos use was associated with higher risk of a police encounter, a delinquent act, and higher incidence of both unique types of acts committed and total frequency of delinquent acts. Prenatal residential proximity to dimethoate use was associated with a higher incidence of police encounters and methomyl with a higher risk of committing a delinquent act. There were no consistent differences when stratified by the number of adverse childhood experiences. CONCLUSIONS: We observed mostly null associations between prenatal residential proximity to agricultural pesticide use and risk-taking behaviors at age 18, with little evidence of effect modification by childhood adversity. There were suggestive associations for chlorpyrifos use with having any police encounter and with all measures of delinquent acts that warrant confirmation in other studies.

Predicting Non-Alcoholic Fatty Liver Disease for Adults Using Practical Clinical Measures: Evidence from the Multi-ethnic Study of Atherosclerosis.

BACKGROUND: Many adults have risk factors for non-alcoholic fatty liver disease (NAFLD). Screening all adults with risk factors for NAFLD using imaging is not feasible. OBJECTIVE: To develop a practical scoring tool for predicting NAFLD using participant demographics, medical history, anthropometrics, and lab values. DESIGN: Cross-sectional. PARTICIPANTS: Data came from 6194 white, African American, Hispanic, and Chinese American participants from the Multi-Ethnic Study of Atherosclerosis cohort, ages 45-85 years. MAIN MEASURES: NAFLD was identified by liver computed tomography (≤ 40 Hounsfield units indicating > 30% hepatic steatosis) and data on 14 predictors was assessed for predicting NAFLD. Random forest variable importance was used to identify the minimum subset of variables required to achieve the highest predictive power. This subset was used to derive (n = 4132) and validate (n = 2063) a logistic regression-based score (NAFLD-MESA Index). A second NAFLD-Clinical Index excluding laboratory predictors was also developed. KEY RESULTS: NAFLD prevalence was 6.2%. The model included eight predictors: age, sex, race/ethnicity, type 2 diabetes, smoking history, body mass index, gamma-glutamyltransferase (GGT), and triglycerides (TG). The NAFLD-Clinical Index model excluded GGT and TG. In the NAFLD-MESA model, the derivation set achieved an AUCNAFLD-MESA = 0.83 (95% CI, 0.81 to 0.86), and the validation set an AUCNAFLD-MESA = 0.80 (0.77 to 0.84). The NAFLD-Clinical Index model was AUCClinical = 0.78 [0.75 to 0.81] in the derivation set and AUCClinical = 0.76 [0.72 to 0.80] in the validation set (pBonferroni-adjusted < 0.01). CONCLUSIONS: The two models are simple but highly predictive tools that can aid clinicians to identify individuals at high NAFLD risk who could benefit from imaging.

Menopausal hormone therapy use and long-term all-cause and cause-specific mortality in the Long Island Breast Cancer Study Project.

Previous studies have observed a reduced mortality risk associated with menopausal hormone therapy (MHT) use among breast cancer survivors. We sought to clarify whether such association could be explained by tumor heterogeneity, specific causes of death, confounding from comorbidities or health behaviors, and a comparison group of women without breast cancer. We interviewed 1508 women newly diagnosed with first primary breast cancer in 1996 to 1997 (~3 months after diagnosis), and 1556 age-matched women without breast cancer, about MHT use history. The National Death Index was used to ascertain vital status after a median of 17.6 years of follow-up (N = 597 deaths for breast cancer subjects). Multivariable-adjusted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) for all-cause mortality, and cause-specific HR (cHR) for breast cancer and cardiovascular disease (CVD). The Fine-Gray model was used to account for competing causes of death. Among women with breast cancer, ever vs never MHT use was inversely associated with all-cause (HR = 0.77, 95%CI = 0.62-0.95), breast cancer-specific (cHR = 0.69, 95%CI = 0.48-0.98), and CVD-specific mortality (cHR = 0.57, 95%CI = 0.38-0.85). Difference of the association was observed in breast cancer-specific mortality according to hormone receptor status (negative tumors: cHR = 0.44, 95%CI = 0.19-1.01; positive tumors: cHR = 0.96, 95%CI = 0.60-1.53). Among the comparison group, we observed similar, but more modest inverse associations for all-cause and CVD-specific mortality. MHT use was inversely associated with mortality after breast cancer, even after accounting for competing causes of death and multiple confounders, and was evident among women without breast cancer. Potential heterogeneity by hormone receptor status requires more study.

Abdominal and gluteofemoral size and risk of liver cancer: The liver cancer pooling project.

Obesity is known to be associated with primary liver cancer (PLC), but the separate effects of excess abdominal and gluteofemoral size are unclear. Thus, we examined the association between waist and hip circumference with risk of PLC overall and by histologic type-hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). The Liver Cancer Pooling Project is a consortium of prospective cohort studies that include data from 1,167,244 individuals (PLC n = 2,208, HCC n = 1,154, ICC n = 335). Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CI) were estimated using proportional hazards regression. Waist circumference, per 5 cm increase, was associated with an 11% increased PLC risk (HR = 1.11, 95%CI: 1.09-1.14), including when adjusted for hip circumference (HR = 1.12, 95%CI: 1.08-1.17) and also when restricted to individuals in a normal body mass index (BMI) range (18.5 to <25 kg/m2 ; HR = 1.14, 95%CI: 1.07-1.21). Hip circumference, per 5 cm increase, was associated with a 9% increased PLC risk (HR = 1.09, 95%CI: 1.06-1.12), but no association remained after adjustment for waist circumference (HR = 0.99, 95%CI: 0.94-1.03). HCC and ICC results were similar. These findings suggest that excess abdominal size is associated with an increased risk of liver cancer, even among individuals considered to have a normal BMI. However, excess gluteofemoral size alone confers no increased risk. Our findings extend prior analyses, which found an association between excess adiposity and risk of liver cancer, by disentangling the separate effects of excess abdominal and gluteofemoral size through utilization of both waist and hip circumference measurements.

Diabetes and cardiovascular disease mortality among a population-based cohort of women with and without breast cancer.

PURPOSE: We investigated whether the relationship between diabetes and all-cause and CVD-related mortality differed between women with and without breast cancer among a cohort drawn from the same source population. METHODS: We interviewed 1,363 women newly diagnosed with breast cancer in 1996-1997, and 1,358 age-matched women without breast cancer, to assess history of physician-diagnosed diabetes. All-cause (n = 631) and CVD-specific mortality (n = 234) was determined by the National Death Index through 2009. We estimated multivariable-adjusted hazard ratios (HRs) for the rates of all-cause and CVD-specific mortality and, to account for competing causes of death, and subdistribution HRs (sHRs) for risk of CVD-related death. RESULTS: Among women with and without breast cancer, respectively, diabetes was associated with: all-cause mortality [HR (95% CI) 1.52 (1.13, 2.05) and 2.17 (1.46, 3.22)]; CVD-specific deaths [1.74 (1.06, 2.84) and 2.06 (1.11, 3.84)]; and risk of CVD-related death [sHR 1.36 (0.81, 2.27) and 1.79 (0.94, 3.40)]. Differences in effect estimates between women with and without breast cancer did not reach statistical significance (p-interaction > 0.10). CONCLUSION: We found that the positive association between a history of physician-diagnosed diabetes and risk of all-cause and CVD-related mortality is of similar magnitude among a population-based cohort of women with or without breast cancer.

A Bayesian Sensitivity Analysis to Partition Body Mass Index Into Components of Body Composition: An Application to Head and Neck Cancer Survival.

Previous studies have suggested a "J-shaped" relationship between body mass index (BMI, calculated as weight (kg)/height (m)2) and survival among head and neck cancer (HNC) patients. However, BMI is a vague measure of body composition. To provide greater resolution, we used Bayesian sensitivity analysis, informed by external data, to model the relationship between predicted fat mass index (FMI, adipose tissue (kg)/height (m)2), lean mass index (LMI, lean tissue (kg)/height (m)2), and survival. We estimated posterior median hazard ratios and 95% credible intervals for the BMI-mortality relationship in a Bayesian framework using data from 1,180 adults in North Carolina with HNC diagnosed between 2002 and 2006. Risk factors were assessed by interview shortly after diagnosis and vital status through 2013 via the National Death Index. The relationship between BMI and all-cause mortality was convex, with a nadir at 28.6, with greater risk observed throughout the normal weight range. The sensitivity analysis indicated that this was consistent with opposing increases in risk with FMI (per unit increase, hazard ratio = 1.04 (1.00, 1.08)) and decreases with LMI (per unit increase, hazard ratio = 0.90 (0.85, 0.95)). Patterns were similar for HNC-specific mortality but associations were stronger. Measures of body composition, rather than BMI, should be considered in relation to mortality risk.

Prediagnosis aspirin use, DNA methylation, and mortality after breast cancer: A population-based study.

BACKGROUND: The authors hypothesized that epigenetic changes may help to clarify the underlying biologic mechanism linking aspirin use to breast cancer prognosis. To the authors' knowledge, this is the first epidemiologic study to examine whether global methylation and/or tumor promoter methylation of breast cancer-related genes interact with aspirin use to impact mortality after breast cancer. METHODS: Prediagnosis aspirin use was assessed through in-person interviews within a population-based cohort of 1508 women diagnosed with a first primary breast cancer in 1996 and 1997. Global methylation in peripheral blood was assessed by long interspersed elements-1 (LINE-1) and the luminometric methylation assay. Promoter methylation of 13 breast cancer-related genes was measured in tumor by methylation-specific polymerase chain reaction and the MethyLight assay. Vital status was determined by the National Death Index through December 31, 2014 (N = 202/476 breast cancer-specific/all-cause deaths identified among 1266 women with any methylation assessment and complete aspirin data). Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs, and the likelihood ratio test was used to evaluate multiplicative interactions. RESULTS: All-cause mortality was elevated among aspirin users who had methylated promotor of BRCA1 (HR, 1.67; 95% CI, 1.26-2.22), but not among those with unmethylated promoter of BRCA1 (HR, 0.99; 95% CI, 0.67-1.45; P for interaction ≤.05). Decreased breast cancer-specific mortality was observed among aspirin users who had unmethylated promotor of BRCA1 and PR and global hypermethylation of LINE-1 (HR, 0.60, 0.78, and 0.63, respectively; P for interaction ≤.05), although the 95% CIs included the null. CONCLUSIONS: The current study suggests that the LINE-1 global methylation and promoter methylation of BRCA1 and PR in tumor may interact with aspirin use to influence mortality after breast cancer.

Breast Cancer Incidence and Exposure to Metalworking Fluid in a Cohort of Female Autoworkers.

Breast cancer is the leading cancer diagnosed among women, and environmental studies have produced few leads on modifiable risk factors for breast cancer. Following an Institute of Medicine recommendation for occupational studies of women highly exposed to potential breast cancer risk factors, we took advantage of an existing cohort of 4,503 female autoworkers in Michigan exposed to metalworking fluid (MWF), complex mixtures of oils and chemicals widely used in metal manufacturing worldwide. Cox proportional hazards models were fit to estimate hazard ratios for incident breast cancer (follow-up, 1985-2013) and cumulative exposure (20-year lag) to straight mineral oils (a known human carcinogen) and water-based soluble and synthetic MWF. Because the state cancer registry began decades after the cohort was defined, we restricted our analyses to subcohorts of women hired closer to the start of follow-up. Among those hired after 1969, the hazard ratio associated with a 1 interquartile-range increase in straight MWF exposure was 1.13 (95% confidence interval: 1.03, 1.23). In separate analyses of premenopausal breast cancer, defined by age at diagnosis, the hazard ratio was elevated for exposure to synthetic MWF (chemical lubricants with no oil content), possibly suggesting a different mechanism in the younger women with breast cancer. This study adds to the limited literature regarding quantitative chemical exposures and breast cancer risk.

Pre-diagnostic aspirin use and mortality after breast cancer.

BACKGROUND: Whether aspirin or other nonsteroidal anti-inflammation drug (NSAID) use is associated with mortality following breast cancer remains unclear. Consideration of use patterns and interaction with obesity may help to clarify the inconsistent results. METHODS: Pre-diagnosis NSAID use, weight, and height were assessed ~ 3 months after diagnosis through in-person interviews with a population-based cohort of 1,442 women with first primary breast cancer. Vital status was determined through the national death index after ~ 18 years of follow-up (N = 237/597 breast cancer-specific/all-cause deaths). We used Cox proportional hazards regression to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Multiplicative interaction by body mass index (BMI) was evaluated using the likelihood ratio test. RESULTS: Ever aspirin use was inversely associated with breast cancer-specific mortality (HR 0.87, 95% CI 0.59-1.29), but positively associated with all-cause mortality (HR 1.21, 95% CI 0.99-1.48); the CIs included the null values. The HRs, however, were more pronounced for the highest level of duration, frequency, regularity, and timing for all-cause, but not breast cancer-specific mortality. Interactions with BMI revealed no significant heterogeneity (pinteraction = 0.37 and pinteraction = 0.36, respectively). CONCLUSION: Pre-diagnosis aspirin use was not strongly associated with mortality following breast cancer. The all-cause mortality associations, however, were slightly stronger when we considered patterns of use.

Interaction between known risk factors for head and neck cancer and socioeconomic status: the Carolina Head and Neck Cancer Study.

Prior studies of squamous cell carcinoma of the head and neck (SCCHN) have explored the effect of socioeconomic status (SES) as an independent risk factor; however, none have investigated the interaction of known risk factors with SES. We examined this using the North Carolina Head and Neck Cancer Epidemiology Study, a population-based case-control study. Incident cases of SCCHN from North Carolina between 2002 and 2006 (n = 1,153) were identified and age, sex, and race-matched controls (n = 1,267) were selected from driver license records. SES measures included household income, educational attainment, and health insurance. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). Current smoking was more strongly associated with SCCHN among those households making < $20,000/year [OR 5.11 (3.61-6.61)] compared to household incomes > $50,000/year [OR 2.47 (1.69-3.25); p interaction < 0.001]. Current drinking was more strongly associated with SCCHN in household incomes < $20,000 [OR 2.91 (2.05-3.78)] compared to > $50,000/year [1.28 (0.97-1.58); p interaction < 0.001]. Current drinkers with less than high school education or income < $20,000 had nearly threefold odds of never-drinkers in the same SES category [OR 2.91 (2.05-3.78); 2.09 (1.39-2.78), respectively]. Our results suggest that the relationship of smoking and alcohol use may be stronger among those of lower SES.

Lung cancer mortality and exposure to synthetic metalworking fluid and biocides: controlling for the healthy worker survivor effect.

OBJECTIVES: Synthetic metalworking fluids (MWFs), widely used to cool and lubricate industrial machining and grinding operations, have been linked with increased risk of several cancers. Estimates of their relation with lung cancer, however, are inconsistent. Controlling for the healthy worker survivor effect, we examined the relations between lung cancer mortality and exposure to synthetic MWF, as well as to biocides added to water-based fluids to control microbial growth, in a cohort of autoworkers. Biocides served as a marker for endotoxin, which has reported antitumour effects, and were hypothesised to be the reason prior studies found reduced lung cancer risk associated with exposure to synthetic fluids. METHODS: Using the parametric g-formula, we estimated risk ratios (RRs) comparing cumulative lung cancer mortality under no intervention with what would have occurred under hypothetical interventions reducing exposure to zero (ie, a ban) separately for two exposures: synthetic fluids and biocides. We also specified an intervention on synthetic MWF and biocides simultaneously to estimate joint effects. RESULTS: Under a synthetic MWF ban, we observed decreased lung cancer mortality risk at age 86, RR=0.96 (0.91-1.01), but when we also intervened to ban biocides, the RR increased to 1.03 (0.95-1.11). A biocide-only ban increased lung cancer mortality (RR=1.07 (1.00-1.16)), with slightly larger RR in younger ages. CONCLUSIONS: Findings suggest a modest positive association for synthetic MWF with lung cancer mortality, contrary to the negative associations reported in earlier studies. Biocide exposure, however, was inversely associated with risk of lung cancer mortality.

Modification of the association between recreational physical activity and survival after breast cancer by promoter methylation in breast cancer-related genes.

BACKGROUND: Mechanisms underlying the inverse association between physical activity and survival after breast cancer are unresolved, but DNA methylation may play a role. We hypothesized that promoter methylation of breast cancer-related genes, as well as global methylation, may modify the association between prediagnostic recreational physical activity (RPA) and breast cancer mortality. METHODS: Using a population-based sample of 1254 women diagnosed with first primary breast cancer, we examined modification of the RPA-mortality association by gene-specific promoter methylation and global methylation. Average lifetime RPA was assessed from menarche to diagnosis through structured in-home interviews. Promoter methylation of 13 breast cancer-related genes was evaluated in archived tumor by methylation-specific polymerase chain reaction and MethyLight assay. Global methylation in white blood cell DNA was determined at long interspersed nucleotide element 1 and by the luminometric methylation assay. After approximately 15 years of follow-up, 486 patients had died, and 186 of the deaths were breast cancer-related. We used Cox proportional hazards regression to estimate HRs and 95% CIs as well as likelihood ratio tests to assess multiplicative interactions. RESULTS: All-cause mortality was lower only among physically active women with methylated promoter of APC (HR 0.60, 95% CI 0.40-0.80), CCND2 (HR 0.56, 95% CI 0.32-0.99), HIN (HR 0.55, 95% CI 0.38-0.80), and TWIST1 (HR 0.28, 95% CI 0.14-0.56) in tumors, but not among those with unmethylated tumors (significant interaction p < 0.05). We found no interaction between RPA and global methylation. CONCLUSIONS: The improved survival after breast cancer that is associated with RPA may be more pronounced in women with promoter tumor methylation in biologically plausible genes.

Assessment of the healthy worker survivor effect in cancer studies of the United Autoworkers-General Motors cohort.

OBJECTIVE: The healthy worker survivor effect (HWSE) can affect the validity of occupational studies when data are analysed incorrectly. HWSE depends on three underlying conditions: (1) leaving work predicts future exposure, (2) leaving work is associated with disease outcome and (3) prior exposure increases probability of leaving work. If all these conditions are satisfied, then employment status is a time-varying confounder affected by prior exposure, and standard regression will produce bias. We assessed these conditions for cancer outcomes in a cohort of autoworkers exposed to metalworking fluids (MWF). METHODS: The cohort includes 31 485 workers followed for cancer incidence from 1985 to 1994. As occupational exposures to straight, soluble and synthetic MWFs are necessarily zero after leaving work, condition (1) is satisfied. Cox models for cancer incidence and for employment termination were used to assess conditions (2) and (3), respectively. Employment termination by select ages was examined to better gauge the presence of condition (2). RESULTS: The HR for leaving work as a predictor of all cancers combined and prostate cancer was null, but elevated for lung and colorectal cancers among men. Condition (2) was more clearly satisfied for all cancer outcomes when leaving work occurred by age 50. Higher exposures to all three MWF types were associated with increased rates of leaving work (condition (3)), with the exception of straight MWF among women. CONCLUSIONS: We found evidence for the structural conditions underlying HWSE in a cohort of autoworkers. G-methods should be applied to reduce HWSE bias in studies of all cancers presently examined.

DNA methylation modifies the association between obesity and survival after breast cancer diagnosis.

Mechanisms underlying the poor breast cancer prognosis among obese women are unresolved. DNA methylation levels are linked to obesity and to breast cancer survival. We hypothesized that obesity may work in conjunction with the epigenome to alter prognosis. Using a population-based sample of women diagnosed with first primary breast cancer, we examined modification of the obesity-mortality association by DNA methylation. In-person interviews were conducted approximately 3 months after diagnosis. Weight and height were assessed [to estimate body mass index (BMI)], and blood samples collected. Promoter methylation of 13 breast cancer-related genes was assessed in archived tumor by methylation-specific PCR and Methyl Light. Global methylation in white blood cell DNA was assessed by analysis of long interspersed elements-1 (LINE-1) and with the luminometric methylation assay (LUMA). Vital status among 1308 patients (with any methylation biomarker and complete BMI assessment) was determined after approximately 15 years of follow-up (N = 194/441 deaths due to breast cancer-specific/all-cause mortality). We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) using two-sided p values of 0.05. Breast cancer-specific mortality was higher among obese (BMI ≥ 30) patients with promoter methylation in APC (HR = 2.47; 95 % CI = 1.43-4.27) and TWIST1 (HR = 4.25; 95 % CI = 1.43-12.70) in breast cancer tissue. Estimates were similar, but less pronounced, for all-cause mortality. Increased all-cause (HR = 1.81; 95 % CI = 1.19-2.74) and breast cancer-specific (HR = 2.61; 95 % CI = 1.45-4.69) mortality was observed among obese patients with the lowest LUMA levels. The poor breast cancer prognosis associated with obesity may depend on methylation profiles, which warrants further investigation.