Height and Breast Cancer Risk: Evidence From Prospective Studies and Mendelian Randomization

BACKGROUND

Epidemiological studies have linked adult height with breast cancer risk in women. However, the magnitude of the association, particularly by subtypes of breast cancer, has not been established. Furthermore, the mechanisms of the association remain unclear.

METHODS

We performed a meta-analysis to investigate associations between height and breast cancer risk using data from 159 prospective cohorts totaling 5216302 women, including 113178 events. In a consortium with individual-level data from 46325 case patients and 42482 control patients, we conducted a Mendelian randomization analysis using a genetic score that comprised 168 height-associated variants as an instrument. This association was further evaluated in a second consortium using summary statistics data from 16003 case patients and 41335 control patients.

RESULTS

The pooled relative risk of breast cancer was 1.17 (95% confidence interval [CI] = 1.15 to 1.19) per 10cm increase in height in the meta-analysis of prospective studies. In Mendelian randomization analysis, the odds ratio of breast cancer per 10cm increase in genetically predicted height was 1.22 (95% CI = 1.13 to 1.32) in the first consortium and 1.21 (95% CI = 1.05 to 1.39) in the second consortium. The association was found in both premenopausal and postmenopausal women but restricted to hormone receptor-positive breast cancer. Analyses of height-associated variants identified eight new loci associated with breast cancer risk after adjusting for multiple comparisons, including three loci at 1q21.2, DNAJC27, and CCDC91 at genome-wide significance level P < 5×10(-8).

CONCLUSIONS

Our study provides strong evidence that adult height is a risk factor for breast cancer in women and certain genetic factors and biological pathways affecting adult height have an important role in the etiology of breast cancer.

Minimum donation intervals should be reconsidered to decrease low hemoglobin deferral in whole blood donors: an observational study

BACKGROUND

Most donor deferrals are due to low hemoglobin (Hb) levels. Previously measured Hb levels and donation intervals are known to be associated with Hb deferral. However, this relationship has never been quantified. In this study, we related the prevalence of Hb deferral to previously measured Hb levels and donation intervals.

STUDY DESIGN AND METHODS

A total of 220,946 whole blood donors were categorized into groups based on their Hb level at the previous donation and on the time interval since the previous donation. For each group, the prevalence of Hb deferral was assessed.

RESULTS

Hb deferral rates were higher when Hb levels at the previous donation were lower and donation intervals were shorter. With a donation interval shorter than 3 months, the prevalence of Hb deferral was below the 10% threshold only when the previous Hb level was at least 0.3 mmol/L above the cutoff level for donation.

CONCLUSION

To maintain appropriate Hb levels, the minimum donation interval of 56 days is only sufficient for donors with Hb levels far above the cutoff level for donation. Protocols for minimum donation intervals should be reconsidered and may be based on previously measured Hb levels. This may result in a decrease of low Hb deferral.

Higher outdoor temperatures are progressively associated with lower blood pressure: a longitudinal study in 100,000 healthy individuals

This study investigated the shape of associations between climate parameters (mean daily temperature and humidity) and systolic and diastolic blood pressure in a large longitudinal cohort of healthy individuals. The study population comprised 101,377 Dutch whole blood and plasma donors (50% men), who made 691,107 visits to the blood bank between 2007 and 2009. Climate parameters were acquired from the Royal Netherlands Meteorological Institute. Associations with blood pressure, measured prior to each blood donation, were studied using (piecewise) linear regression analyses within Generalized Estimating Equation models. On average, systolic blood pressure was 0.18 mm Hg, and diastolic blood pressure was 0.11 mm Hg lower per one degree Celsius higher mean daily temperature. Higher daily temperatures were associated with lower blood pressure, independent of humidity and potentially confounding factors. These associations were stronger at older age and higher temperatures. Seasonality should therefore be taken into account when monitoring blood pressure, particularly in older individuals.

Low-grade inflammation and endothelial dysfunction explain the association between retinopathy and left ventricular ejection fraction in men: an 8-year follow-up of the Hoorn Study

PURPOSE

The aim of this study was to prospectively investigate the association of retinopathy with changes in left ventricular (LV) function.

METHODS

Within the Hoorn Study, a population-based cohort study of diabetes in The Netherlands, retinal photography and echocardiography were performed in the year 2000 (baseline) and 2008 (follow-up). Retinopathy was graded according to the Eurodiab classification and further defined as absent or present retinopathy. LV systolic and diastolic functions were assessed by LV ejection fraction (%), LV mass (g/m(2.7)) and left atrial (LA) volume indices and the ratio of LV inflow (E) and early diastolic lengthening (e') velocities. Linear regression analyses stratified for sex were completed to investigate associations of retinopathy with changes in LV function in participants with impaired glucose metabolism and type 2 diabetes.

RESULTS

One hundred forty-seven participants (58% men, mean age 66) were included in the study, of whom 13.6% were present with retinopathy at baseline. LV ejection fraction was similar among participants with and without retinopathy (60.2% versus 60.7%) at baseline. Eight years later, retinopathy was significantly associated with a lower LV ejection fraction (β -8.0 95% CI -15.37 to -0.68) in men, independent of risk factors. Microvascular endothelial dysfunction ([ED] β -4.87 95% CI -13.40 to 3.67) and low-grade inflammation ([LGI] β -5.30 95% CI -13.72 to 3.12) both diminished the association. No significant associations between retinopathy and other LV function parameters were observed.

CONCLUSION

Retinopathy was significantly associated with a lower LV ejection fraction in men but not in women. LGI and ED might explain the observed association.

Local stiffness of the carotid and femoral artery is associated with incident cardiovascular events and all-cause mortality: the Hoorn study

OBJECTIVES

This study sought to investigate the association of local and segmental arterial stiffness with incident cardiovascular events and all-cause mortality.

BACKGROUND

The association of different stiffness indices, in particular of carotid, brachial, and femoral stiffness, with cardiovascular disease and mortality is currently unknown.

METHODS

In a population-based cohort (n = 579, mean age 67 years, 50% women, 23% with type 2 diabetes [by design]), we assessed local stiffness of carotid, femoral, and brachial arteries (by ultrasonography), carotid-femoral pulse wave velocity (cfPWV), aortic augmentation index, and systemic arterial compliance.

RESULTS

After a median follow-up of 7.6 years, 130 participants had a cardiovascular event and 96 had died. The hazard ratios (HRs) (95% confidence intervals [CIs]) per 1 SD for cardiovascular events and all-cause mortality, respectively, were HR: 1.22 (95% CI: 0.95 to 1.56) and 1.51 (95% CI: 1.11 to 2.06) for lower carotid distensibility; HR: 1.19 (95% CI: 1.00 to 1.41) and 1.28 (95% CI: 1.07 to 1.53) for higher carotid elastic modulus; HR: 1.08 (95% CI: 0.88 to 1.31) and 1.43 (95% CI: 1.10 to 1.86) for lower carotid compliance; HR: 1.39 (95% CI: 1.06 to 1.83) and 1.27 (95% CI: 0.90 to 1.79) for lower femoral distensibility; HR: 1.25 (95% CI: 0.96 to 1.63) and 1.47 (95% CI: 1.01 to 2.13) for lower femoral compliance; and HR: 1.56 (95% CI: 1.23 to 1.98) and 1.13 (95% CI: 0.83 to 1.54) for higher cfPWV. These results were adjusted for age, sex, mean arterial pressure, and cardiovascular risk factors. Mutual adjustments for each of the other stiffness indices did not materially change these results. Brachial stiffness, augmentation index, and systemic arterial compliance were not associated with cardiovascular events or mortality.

CONCLUSIONS

Carotid and femoral stiffness indices are independently associated with incident cardiovascular events and all-cause mortality. The strength of these associations with events may differ per stiffness parameter.

Prospective associations of B-type natriuretic peptide with markers of left ventricular function in individuals with and without type 2 diabetes: an 8-year follow-up of the Hoorn Study

OBJECTIVE

Heart failure is common in individuals with type 2 diabetes, and early detection of individuals at risk may offer opportunities for prevention. We aimed to explore 1) prospective associations of B-type natriuretic peptide (BNP) levels in a non-heart failure range with changes in markers of left ventricular (LV) function and 2) possible effect modification by type 2 diabetes in a population-based cohort.

RESEARCH DESIGN AND METHODS

Echocardiographic measurements were performed at baseline (2000-2001) and follow-up (2007-2009), together with standardized physical examinations and BNP measurements on 300 individuals (mean age 66 years, 32% with type 2 diabetes) of the longitudinal Hoorn Study. Multivariate linear regression analyses were performed to investigate associations of baseline BNP (<100 pg/mL) in individuals without prevalent heart failure at baseline with changes in LV mass index, LV ejection fraction, left atrial volume index, and ratio of early diastolic LV inflow velocity (E) to early diastolic lengthening velocity (e') (E/e').

RESULTS

In all individuals, higher BNP was associated with 8-year increases in left atrial volume index. Higher BNP was also associated with increasing LV mass index and E/e'. These associations were significantly stronger in individuals with type 2 diabetes compared with the nonsignificant associations in individuals without type 2 diabetes.

CONCLUSIONS

This 8-year follow-up study shows that higher BNP levels in a non-heart failure range were associated with an increased LV mass and deteriorated LV diastolic function, particularly in individuals with type 2 diabetes. This implies that the presence or absence of type 2 diabetes should be taken into account if BNP levels are used to assess future heart failure risk.

Independent associations of glucose status and arterial stiffness with left ventricular diastolic dysfunction: an 8-year follow-up of the Hoorn Study

OBJECTIVE

To investigate relative contributions of glucose status and arterial stiffness to markers of left ventricular (LV) systolic and diastolic dysfunction after 8 years of follow-up.

RESEARCH DESIGN AND METHODS

In the population-based prospective Hoorn Study, 394 individuals with preserved LV systolic and diastolic function participated, of whom 87 had impaired glucose metabolism and 128 had type 2 diabetes. Measurements including arterial ultrasound and echocardiography were performed according to standardized protocols.

RESULTS

The presence of type 2 diabetes was associated with more severe LV systolic and diastolic dysfunction 8 years later: LV ejection fraction was 2.98% (95% CI 0.46-5.51) lower, and left atrial (LA) volume index, LV mass index, and tissue Doppler-derived E/e' were 3.71 mL/m(2) (1.20-6.22), 5.86 g/m(2.7) (2.94-8.78), and 1.64 units (0.95-2.33) higher, respectively. Furthermore, presence of impaired glucose metabolism or type 2 diabetes was associated with 8-year increases in LV mass index. More arterial stiffness (measured as a lower distensibility) was associated with LV diastolic dysfunction 8 years later: LA volume index, LV mass index, and E/e' at follow-up were higher. Subsequent adjustments for baseline mean arterial pressure and/or LV diastolic dysfunction did not eliminate these associations. Associations of type 2 diabetes and arterial stiffness with markers of LV diastolic dysfunction were largely independent of each other.

CONCLUSIONS

Both glucose status and arterial distensibility are independently associated with more severe LV diastolic dysfunction 8 years later and with deterioration of LV diastolic dysfunction. Therefore, type 2 diabetes and arterial stiffness may relate to LV diastolic dysfunction through different pathways.

Long-term exposure to traffic-related air pollution and type 2 diabetes prevalence in a cross-sectional screening-study in the Netherlands

BACKGROUND

Air pollution may promote type 2 diabetes by increasing adipose inflammation and insulin resistance. This study examined the relation between long-term exposure to traffic-related air pollution and type 2 diabetes prevalence among 50- to 75-year-old subjects living in Westfriesland, the Netherlands.

METHODS

Participants were recruited in a cross-sectional diabetes screening-study conducted between 1998 and 2000. Exposure to traffic-related air pollution was characterized at the participants' home-address. Indicators of exposure were land use regression modeled nitrogen dioxide (NO2) concentration, distance to the nearest main road, traffic flow at the nearest main road and traffic in a 250 m circular buffer. Crude and age-, gender- and neighborhood income adjusted associations were examined by logistic regression.

RESULTS

8,018 participants were included, of whom 619 (8%) subjects had type 2 diabetes. Smoothed plots of exposure versus type 2 diabetes supported some association with traffic in a 250 m buffer (the highest three quartiles compared to the lowest also showed increased prevalence, though non-significant and not increasing with increasing quartile), but not with the other exposure metrics. Modeled NO2-concentration, distance to the nearest main road and traffic flow at the nearest main road were not associated with diabetes. Exposure-response relations seemed somewhat more pronounced for women than for men (non-significant).

CONCLUSIONS

We did not find consistent associations between type 2 diabetes prevalence and exposure to traffic-related air pollution, though there were some indications for a relation with traffic in a 250 m buffer.

Prevalence of overweight and obesity in the Netherlands in 2003 compared to 1980 and 1997

OBJECTIVE

To assess the prevalence of overweight and obesity in children living in the Netherlands and compare the findings with the Third and Fourth National Growth Studies carried out in 1980 and 1997, respectively.

DESIGN AND METHODS

Data were obtained from the child health care system. International cut-off points for body mass index (BMI) were used to determine overweight and obesity. Cases were weighted for ethnicity and municipality size in such a way that the sample matched the distribution in the general population. The LMS method was used to calculate the age-related distribution of BMI, and the prevalence was calculated from the fitted distribution.

PATIENTS

Data on 90 071 children aged 4-16 years were routinely collected by 11 community health services during 2002-2004.

RESULTS

On average, 14.5% of the boys and 17.5% of the girls were overweight (including obesity), which is a substantial increase since 1980 (boys 3.9%, girls 6.9%) and 1997 (boys 9.7%, girls 13.0%). Similarly, 2.6% of the boys and 3.3% of the girls aged 4-16 years were obese, which is much higher than in 1980 (boys 0.2%, girls 0.5%) and 1997 (boys 1.2%, girls 2.0%). At the age of 4, 12.3% of the boys and 16.2% of the girls were already overweight.

CONCLUSIONS

The prevalence of overweight and obesity in the Netherlands is still rising, and at an even faster rate than before. Evidence-based interventions are needed to counter the obesity epidemic, and there is an urgent need for pre-school intervention programmes.