Ethnic Variations in Estrogen and Its Metabolites: Sufficient to Explain Differences in Breast Cancer Incidence Rates?

[Sex differences in stroke mortality in Thailand : A National cohort study]

BACKGROUND

Over half of the growing global stroke-mortality burden is accounted for by the East-Asian-subcontinent alone. Sex differences in stroke-mortality in the Asian population is yet to be assessed in the literature. We aimed to assess the sex-differences in mortality following stroke in a large cohort of Thai-patients.

METHOD

All stroke admissions between 2004-2015 were included from the Thailand public-health-insurance-database. The association between sex and mortality was assessed in-hospital, at 1 month, 1 year and 5 years, using multivariable Cox-regressions, separately for ischaemic-stroke (IS), haemorrhagic-stroke (HS) and stroke-of-undetermined-type(SUT), adjusting for confounders.

RESULTS

608,890 patients were included: 370,527 patients with IS(60.9%), 173,236 with HS(28.5%) and 65,127 with SUT(10.6%). Women were older than men in all three groups and had higher prevalence of comorbidities. Adjusted hazard-ratios(HRs) of mortality showed women had higher mortality post-IS compared to men (in-hospital: HR: 1.20; 95% CI: 1.17-1.23; 1 month: HR: 1.17; 95% CI: 1.15-1.20; 1 year: HR: 1.10; 95% CI: 1.09-1.12 and 5 years: HR: 1.02; 95% CI: 1.01-1.03). Women also had higher mortality after HS (in-hospital: HR: 1.02; 95% CI: 1.00-1.04; 1 month: HR: 1.08; 95% CI: 1.06-1.10; 1 year: HR: 1.04; 95% CI: 1.03-1.06 and 5 years: HR: 1.09; 95% CI: 1.08-1.11), and SUT (in-hospital: HR: 1.04; 95% CI: 1.03-1.06; 1 month: HR: 1.20; 95% CI: 1.14-1.27; 1 year: HR: 1.14; 95% CI: 1.09-1.18 and 5 years: HR: 1.06; 95% CI: 1.03-1.10).

CONCLUSIONS

Compared to men, women were older at time of stroke-diagnosis and had higher burden of stroke risk-factors. Women also had higher mortality after stroke regardless of stroke-type or duration since stroke-onset. Post-IS, excess stroke-mortality in women was greatest during the in-hospital period, whereas excess stroke-mortality increased with time in women who had HS. No clear relationship was found between duration since stroke-onset and mortality in patients who had SUT.

Exploration of Racial Differences in Reproductive Factors for Breast Cancer among Women aged 55-74

Background Reproductive factors have been well-documented risk factors for breast cancer. Few studies have examined whether the associations between reproductive factors and breast cancer differed across races/ethnicities. Methods We analyzed a sub-sample (70, 734) of the Prostate, Lung, Colorectal, and Ovarian (PLCO) dataset. Participants with valid baseline questionnaire and without breast cancer at enrollment were included into analysis. We stratified the participants into subgroups based on their races/ethnicities then estimated the effects of the reproductive factors on breast cancer within each group using Cox-proportion regression models. Results Oral contraceptive use (HR=1.09, 95% confidence interval or CI=1.01, 1.18), advanced age at natural menopause (HR=1.25, 95% CI=1.06, 1.49) were associated with increased risk of breast cancer in non-Hispanic Caucasians group only. Long term use of menopausal hormone therapy (more than five years) was associated with increased risk of breast cancer in both of the non-Hispanic Caucasian (HR=1.44, 95% CI=1.31, 1.59) group and the non-Hispanic Asian/Pacific Islander (HR=1.98, 95% CI=1.23, 3.20) group, but not in other race/ethnic groups. Hispanics who tried to become pregnant for a year or more had increased risk of breast cancer (HR=2.60, 95% CI=1.05, 6.46) than their counterparts without difficulty in getting pregnancy. In addition, surgery induced menopause was found to be a protective factor for breast cancer in non-Hispanic Caucasian (HR=0.88, 95% CI=0.79, 0.98) group only.

Conclusions We concluded that different races/ethnicities had different breast cancer related reproductive risk factors. Non-Hispanic Caucasians had the most breast cancer related reproductive risk factors, while the minorities had none or few breast cancer related reproductive risk factors and among these few factors only 1 was also risk factor for non-Hispanic Caucasians.