Background
Insulin resistance is associated with higher all‐cause and cancer‐specific mortality in postmenopausal women. However, to the authors' knowledge, information regarding insulin resistance ...and breast cancer mortality risk is limited. Therefore, the authors examined associations between insulin resistance and breast cancer incidence and mortality in a subsample of Women's Health Initiative participants.
Methods
A total of 22,837 postmenopausal women with fasting baseline glucose and insulin levels were followed for incident breast cancer and breast cancer mortality. Breast cancers were verified by medical record review and serial National Death Index linkage–enhanced mortality findings. Insulin resistance was estimated using the homeostatic model assessment of insulin resistance (HOMA‐IR). Multivariable Cox proportional hazards models were used to compute hazard ratios (HRs) with 95% confidence intervals (95% CIs) for quartile comparisons. Outcomes included breast cancer incidence, deaths from breast cancer, and deaths after breast cancer (breast cancer followed by death from any cause).
Results
During a median of 19.8 years of follow‐up of 1328 breast cancer cases, there were 512 deaths reported, 151 of which were from breast cancer. Breast cancer incidence was higher in women in the highest HOMA‐IR quartile (HR, 1.34; 95% CI, 1.12‐1.61 P for trend = .003). Although HOMA‐IR was not found to be associated with risk of death from breast cancer (HR, 1.04; 95% CI, 0.60‐1.79), women in the highest versus those in the lowest HOMA‐IR quartile were at a higher risk of death after breast cancer (HR, 1.78; 95% CI, 1.32‐2.39 P for trend <.001).
Conclusions
Higher levels of insulin resistance in postmenopausal women are associated with higher breast cancer incidence and higher all‐cause mortality after breast cancer.
In the current study, insulin resistance is estimated in a cohort of 22,837 postmenopausal women with fasting glucose and insulin determinations. After nearly 20 years of follow‐up, higher levels of insulin resistance appear to be associated with higher breast cancer incidence and higher all‐cause mortality after breast cancer.
Fiber intake may be associated with lower risk of metabolic syndrome (MetS) but data from metabolically unhealthy African American women is sparse. We examined the association of dietary fiber intake ...and MetS among postmenopausal African American women with obesity. Baseline cross-sectional data from the Focused Intervention on Exercise to Reduce CancEr (FIERCE) trial of 213 women (mean age 58.3 years) were used. Dietary intake was assessed by Food Frequency Questionnaires (FFQs). Multivariate linear and logistic regressions were performed to estimate associations of MetS with fiber intake and adherence to dietary fiber intake guidelines, respectively. Mean daily fiber intake was (10.33 g/1000kcal) in women with impaired metabolic health. We observed an inverse association of total fiber intake with MetS. One unit increase in energy-adjusted fiber intake was associated with a 0.10 unit decrease in the MetS z-score (p = 0.02). Similar results were obtained for both soluble and insoluble fiber. In multivariate-adjusted analyses, participants not adherent to fiber intake recommendations were more likely to have MetS as compared to those reporting intakes in the recommended range (adjusted odds ratio 4.24, 95% CI: 1.75, 10.30). Of the MetS components, high fasting glucose and high triglycerides were all associated with lower intake of fiber. Study participants who consumed a higher amount of fiber had a better overall metabolic profile and were less likely to have MetS in our cross-sectional analysis of postmenopausal African American women with obesity and unhealthy metabolic profiles.
Better information on lung cancer occurrence in lifelong nonsmokers is needed to understand gender and racial disparities and to examine how factors other than active smoking influence risk in ...different time periods and geographic regions.
We pooled information on lung cancer incidence and/or death rates among self-reported never-smokers from 13 large cohort studies, representing over 630,000 and 1.8 million persons for incidence and mortality, respectively. We also abstracted population-based data for women from 22 cancer registries and ten countries in time periods and geographic regions where few women smoked. Our main findings were: (1) Men had higher death rates from lung cancer than women in all age and racial groups studied; (2) male and female incidence rates were similar when standardized across all ages 40+ y, albeit with some variation by age; (3) African Americans and Asians living in Korea and Japan (but not in the US) had higher death rates from lung cancer than individuals of European descent; (4) no temporal trends were seen when comparing incidence and death rates among US women age 40-69 y during the 1930s to contemporary populations where few women smoke, or in temporal comparisons of never-smokers in two large American Cancer Society cohorts from 1959 to 2004; and (5) lung cancer incidence rates were higher and more variable among women in East Asia than in other geographic areas with low female smoking.
These comprehensive analyses support claims that the death rate from lung cancer among never-smokers is higher in men than in women, and in African Americans and Asians residing in Asia than in individuals of European descent, but contradict assertions that risk is increasing or that women have a higher incidence rate than men. Further research is needed on the high and variable lung cancer rates among women in Pacific Rim countries.
African American (AA) women are more likely than white women to be obese and to be diagnosed with ER− and triple-negative (TN) breast cancer, but few studies have evaluated the impact of obesity and ...body fat distribution on breast cancer subtypes in AA women. We evaluated these associations in the AMBER Consortium by pooling data from four large studies. Cases were categorized according to hormone receptor status as ER+, ER−, and TN (ER−, PR−, and HER2−) based on pathology data. A total of 2104 ER+ cases, 1070 ER− cases (including 491 TN cases), and 12,060 controls were included. Odds ratios (OR) and 95 % confidence intervals (CI) were computed using logistic regression, taking into account breast cancer risk factors. In postmenopausal women, higher recent (most proximal value to diagnosis/index date) BMI was associated with increased risk of ER+ cancer (OR 1.31; 95 % CI 1.02–1.67 for BMI ≥35 vs. <25 kg/m
2
) and with decreased risk of TN tumors (OR 0.60; 95 % CI 0.39–0.93 for BMI ≥35 vs. <25). High young adult BMI was associated with decreased premenopausal ER+ cancer and all subtypes of postmenopausal cancer, and high recent waist-to-hip ratio with increased risk of premenopausal ER+ tumors (OR 1.35; 95 % CI 1.01–1.80) and all tumor subtypes combined in postmenopausal women (OR 1.26; 95 % CI 1.02–1.56). The impact of general and central obesity varies by menopausal status and hormone receptor subtype in AA women. Our findings imply different mechanisms for associations of adiposity with TN and ER+ breast cancers.
Adherence to cancer prevention recommendations has been associated with lower incidence of breast cancer in previous studies, but evidence in African American women is limited. This project evaluated ...the association between adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations and breast cancer incidence among African American women. The Black Women's Health Study (analytic cohort = 49,103) is an ongoing prospective cohort study of African American women, ages 21–69 years at baseline (1995). Adherence scores for seven WCRF/AICR recommendations (adherent = 1, partial adherence = 0.5, non‐adherence = 0) were calculated using questionnaire data and summed for overall (maximum = 7) and diet only (maximum = 5) scores. Associations between baseline and time‐varying adherence scores and breast cancer incidence (N = 1,827 incident cases through 2011) were evaluated using proportional hazards regression. In this cohort, 8.5% adhered >4 recommendations. Adherence at baseline was not associated with breast cancer incidence. Higher overall time‐varying adherence (per 0.5 point increase) was associated with lower breast cancer incidence (HR: 0.90, 95% CI: 0.84–0.96). Adherence to physical activity, sugar beverage and red and processed meat recommendations were also associated with reduced risk. Adherence to the WCRF/AICR recommendations was low and may be associated with lower breast cancer incidence in African American women.
What's new?
Diet, physical activity, and body composition are all potential modifiable risk factors in breast cancer and important targets for primary prevention. But while adherence to cancer prevention recommendations has been associated with lower incidence of breast cancer, evidence in African American women is limited. This study evaluated the association between adherence to cancer prevention recommendations of the World Cancer Research Fund/American Institute for Cancer Research and breast cancer incidence among African American women. The results suggest that work is needed to improve adherence to recommendations among African American women, with the potential to reduce breast cancer incidence through increased adherence.
Estrogen receptor (ER)-negative breast tumors and progesterone receptor (PR)-negative breast tumors occur more commonly in women of African ancestry. Recent research indicates that the effects of ...reproductive factors may differ by hormone receptor status. We assessed the relation of parity and lactation to incidence of ER(-)/PR(-) and ER(+)/PR(+) breast cancer in a cohort of African American women.
From 1995-2009, 457 incident cases of ER(+)/PR(+) and 318 cases of ER(-)/PR(-) breast cancer were confirmed by review of pathology data among 59,000 African American women followed in the Black Women's Health Study through biennial questionnaires. HRs and two-sided 95% CIs for the incidence of breast cancer subtypes were derived from proportional hazards regression models that controlled for age, reproductive variables, and breast cancer risk factors.
Higher parity was associated with an increased risk of ER(-)/PR(-) breast cancer (HR = 1.48, 95% CI: 0.98-1.84 for 3+ versus 0 births, P(trend) = 0.009), and with a reduced risk of ER(+)/PR(+) cancer (HR = 0.53, 95% CI: 0.39-0.73 for 3+ versus 0 births, P(trend) = 0.0002). Among women who had breastfed, high parity was no longer associated with increased incidence of ER(-)/PR(-) breast, but the inverse association with ER(+)/PR(+) cancer persisted.
The higher incidence of ER(-)/PR(-) breast cancer in African American women may be explained in part by their higher parity and lower prevalence of breastfeeding relative to white women.
Increased breastfeeding may lead to a reduction in the incidence of this breast cancer subtype.
In 2015, representatives from 4 leading cancer organizations -- the American Association for Cancer Research, the American Cancer Society, the American Society for Clinical Oncology, and the NCI -- ...began to meet to discuss the state of health disparities in the US. These discussions involved the state of cancer health disparities research and what could be done to move it forward. This statement presents a unified strategy among 4 of the leading cancer organizations in the US to promote cooperation among investigators in all areas of the cancer health disparities research community, to ensure that cancer research benefits all populations and patients regardless of race, ethnicity, age, gender identity, sexual orientation, SES, or the communities in which they live.
Black women have higher lung cancer incidence and mortality rates despite a lower smoking prevalence than White women. Physical activity may reduce lung cancer risk through several pathways, ...including the immune and inflammatory systems, as well as those with effects on sex hormones and metabolism.
We examined vigorous physical activity, walking for exercise, sitting watching television, and metabolic equivalents (METs) in relation to lung cancer risk among 38,432 participants in a prospective cohort of Black women. We used Cox proportional hazards models adjusted for covariates to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).
In 1995–2017, 475 incident lung cancer cases accrued. Participants who engaged in ≥ 1 h/week of vigorous physical activity or expended the highest tertile of METs experienced a decreased risk of lung cancer (HR: 0.85, 95% CI: 0.65–1.10; 0.89, 0.68–1.18; respectively). An increased risk was observed for sitting watching television (≥1 h/week: 1.27, 0.72–2.21). In stratified models, an inverse association between walking for exercise and lung cancer risk was only present among former smokers (≥1 h/week: 0.71, 0.52–0.98), while inverse associations between vigorous physical activity (≥1 h/week: 0.45, 0.28–0.73) and METs (tertile 3: 0.54, 0.34–0.85) and lung cancer risk were present among smokers with ≥ 20 pack-years.
Physical activity may play a role in reducing lung cancer risk among Black women, particularly among smokers. Future studies should explore biologic mechanisms whereby physical activity may influence carcinogenesis and investigate the role of exercise interventions in reducing lung cancer risk among smokers.
•Racial differences in lung cancer are not explained by smoking prevalence.•We found that walking for exercise reduced lung cancer risk among former smokers.•Vigorous exercise was inversely associated with cancer risk in a subset of smokers.•Physical activity may reduce lung cancer risk among smokers.
Data on ethnic variations in breast density are limited and often not inclusive of underrepresented minorities. As breast density is associated with elevated breast cancer risk, investigating racial ...and ethnic difference may elucidate the observed differences in breast cancer risk among different populations. We reviewed breast density from initial screening of women from the Capital Breast Care Center and Georgetown University Hospital from 2010 to 2014. Patient demographics including race, age at screening, education, menopausal status, and body mass index were ed. We recorded the BI‐RADS density categories: (1) “fatty,” (2) “scattered fibroglandular densities,” (3) “heterogeneously dense,” and (4) “extremely dense.” Multivariable unconditional logistic regression was used to identify predictors of breast density. Density categorization was recorded for 2146 women over the 5‐year period, comprising Blacks (n = 940), Hispanics (n = 893), and Whites (n = 314). Analysis of subject characteristics by breast density showed that high category is observed in younger, Hispanic, nulliparous, premenopausal, and nonobese women (t‐test or chi‐square test, P‐values <.0001). Obese women are 70% less likely to have high density. Being Hispanic, premenopausal, and nonobese were predictive of high density on logistic regression. In this analysis of density distribution in a diverse sample, Hispanic women have the highest breast density, followed by Blacks and Whites. Unique in our findings is women who identify as Hispanic have the highest breast density and lower rates of obesity. Further investigation of the impact of obesity on breast density, especially in the understudied Hispanic group is needed.
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