2017

Type 2 diabetes has been associated with increased risk of developing breast cancer among white women. While type 2 diabetes occurs much more commonly among Black women, little is known about its relation to breast cancer incidence among Black women. In the BWHS, we found that type 2 diabetes was not associated with the risk of estrogen receptor-positive (ER+) breast cancer, whereas risk of estrogen receptor-negative (ER-) breast cancer was 40% greater among women with type 2 diabetes than among unaffected women. The high prevalence of type 2 diabetes in Black women could be contributing to the higher incidence of ER- breast cancer, an aggressive subtype, relative to that in other population groups.  link to online article

African American women have a higher incidence of aggressive breast cancer at younger ages. Using data from the AMBER Consortium, a consortium of studies of breast cancer in African American (AA) women that includes the BWHS, we examined tumor characteristics and breast cancer risk factors associated with breast cancer occurring among premenopausal women at ages <40 and 40 or older. Women <40 years old had a higher frequency of poorer-prognosis tumors compared with older women. Waist-to-hip ratio and family history of breast cancer were more strongly associated with younger-onset disease, and breastfeeding appeared protective among younger women. Oral contraceptive use with associated with increased risk regardless of age. Based on these results, it may be possible to reduce breast cancer in young women by modifying waist-to-hip ratio, oral contraceptive use, and breastfeeding.  link to online article

Race is a strong risk factor for uterine fibroids, a condition that affects the majority of women by the time they reach menopause and disproportionately affects African American women. The Black Women’s Health Study participated in an analysis that assessed genetic risk factors for fibroids. We identified a new risk locus within the gene CYTH4 that impacts gene expression in the thyroid that had a statistically significant association with fibroid risk among African American women.  link to online article

We assessed the contributions of height, the age at which maximum height is reached, and age at menarche (start of menstruation) to the risk of the major subtypes of breast cancer, estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-). Height was associated with higher risk of ER+ cancer, and early age at attained height with and early age at menarche with increased risk of both ER+ and ER- cancer. These findings give clues as to how and when risk of breast cancer is established.  link to online article

BWHS participants have been asked questions about experience with interpersonal racism in daily life (everyday racism) and lifetime racism with respect to police, housing, and work. We assessed racism in relation to type 2 diabetes from 1995 through 2011 in the BWHS, during which time 5,344 women were diagnosed with diabetes. Both everyday and lifetime racism were associated with increased risk of developing type 2 diabetes.  Increased weight associated with racism accounted for about half of the increase in risk.  link to online article

The incidence of advanced breast cancer among premenopausal women has increased in recent decades, although it is still relatively rare compared to incidence among postmenopausal women. In order to have a large enough sample size for informative study of premenopausal breast cancer, many studies must band together. The Premenopausal Breast Cancer Collaborative Group has just been formed with the purpose of studying specific subtypes of premenopausal breast cancer, and the BWHS will be a key contributor to this effort.  link to online article

The association between breast feeding and risk of endometrial cancer was assessed in data from 17 studies participating in the Epidemiology of Endometrial Cancer Consortium. The analyses included 8,981 women with endometrial cancer and 17,241 women in a control group. Ever breastfeeding was associated with an 11% reduction in risk of endometrial cancer. Longer average duration of breastfeeding per child was associated with lower risk of endometrial cancer, although there appeared to be some leveling of this effect beyond 6-9 months. Our findings suggest that reducing endometrial cancer risk can be added to the list of maternal benefits associated with breastfeeding.  link to online article

Genome-wide association studies have identified approximately 100 common genetic variants associated with breast cancer risk, mostly among white women. 74 breast cancer risk variants and genetic variants in associated regions were assessed in 6,522 breast cancer cases and 7,643 controls of African ancestry from three large consortial studies. We found confirmatory evidence for 73% of the 74 variants. Other variants in the regions that were better risk markers for breast cancer were also found. Thus, we have identified genetic variants that better characterize breast cancer risk in women of African ancestry.  link to online article

In a collaborative study, genetic variants across the genome were assessed in relation to colorectal cancer in African Americans (AA). A novel genetic variant associated with risk in AAs was identified, as well as another variant that had a stronger association in AAs than in other ethnic groups.  link to online article

We studied the relation of reproductive factors to incidence of endometrial cancer in the BWHS, based on 300 women who were affected by the condition during  18 years of follow-up. Earlier age at start of menstruation was associated with higher risk and later age at first birth with lower risk. Women who had had children were at lower risk than those who had not had children. These results suggests that these factors have similar associations with endometrial cancer in black and white women.  link to online article

Vitamin D levels differ between African American (AA) and European Americans (EA), with many more AAs being vitamin D deficient. Vitamin D deficiency may be related to incidence of several illnesses. Levels of vitamin D (i.e., 25(OH)D) and of vitamin D-binding protein (VDBP) in AA and EA women were compared. AA women had lower levels of vitamin D but similar levels of VDBP as EA women. Demographic and lifestyle determinants of vitamin D were similar in the two populations, but genetic determinants may be ethnicity specific.  link to online article

In genetic studies, some genes in the Wnt pathway have been found to be associated with type 2 diabetes. Other genes in the pathway were assessed in a collaborative study of African Americans. A new variant that may represent a signal seen only in African ancestry populations was identified. The finding needs to be replicated.  link to online article

Numerous studies have linked heavy alcohol consumption to an increase in breast cancer incidence. In a study of data from the BWHS and three other studies of African American women, consumption of at least seven drinks per week was associated with a small increase in risk of breast cancer in the overall data. However, the results among the four studies were not consistent.  link to online article

Periodontitis (infections of the gums and bone) occur commonly. To study risk factors for periodontitis and effects of periodontitis on health requires adequate reporting of the condition. BWHS participants living in Massachusetts in the Boston metropolitan area were invited to participate in a study of the validity of reporting of dental conditions, which involved having a clinical examination by a dentist. A total of 77 BWHS participants were examined for periodontal disease, and their questionnaire responses about dental disease were compared with the clinical data. Accuracy of reporting was similar to that in other populations, and it was sufficient for studies of periodontitis in the BWHS based on self-report.  link to online article

Both mortality from breast cancer and the occurrence of diabetes are higher in Black women than White women. We assessed whether diabetes may be contributing to mortality among breast cancer survivors in the BWHS. Based on over 1,600 participants who had been diagnosed with breast cancer, we found that breast cancer mortality was increased among those who had been diagnosed with diabetes at least 5 years before breast cancer occurrence. The increase was present for both estrogen rector positive and estrogen receptor negative breast cancer. The results suggest that diabetes contributes to breast cancer mortality among women with breast cancer.  link to online article

Extensive evidence in white women has linked oral contraceptive use, tubal ligation (tubes tied), and higher parity (greater number of children) with reduced risk of ovarian cancer. Results on supplemental female hormones used for the menopause are inconsistent. We studied these factors in the BWHS. The associations of oral contraceptive use, tubal ligation, and parity with ovarian cancer in the BWHS were similar to those in white women. The results suggested that use of female hormone supplements may be associated with increased risk, but more studies are needed to be certain.  link to online article

Ozone is a commonly occurring air pollutant. Because ozone can lead to insulin resistance, we studied the relation of ozone levels to incidence of type 2 diabetes in the BWHS. We found evidence of increases in diabetes  risk associated with higher ozone levels. While other factors, such as obesity, have a much stronger relationship with diabetes, this first evidence on a possible association of ozone with the occurrence of diabetes supports the need for continuing research on potential adverse effects of air pollution. link to online article

Air pollutants can increase blood pressure. We studied levels of traffic-related nitrogen dioxide (NO2) and of ozone in relation to the incidence of hypertension in the BWHS. Over a period of 16 years, 9,570 new cases of hypertension were identified. Higher ozone levels were associated with increased risk of hypertension, but higher NO2 levels were associated with decreased risk.  link to online article

A polymorphism in the TP53 gene and has been shown to reduce tumor suppression in mice. To explore whether this polymorphism affects cancer risk in people of African descent, we analyzed genetic data from 6,907 women with breast cancer and 7,644 women without cancer from the AMBER, ROOT, and AABC consortia. We found no evidence of an association with breast cancer among all participants, but there was increased risk among premenopausal women. More studies of this genetic variant in human populations are needed. However, the frequency of this polymorphism is low in women of African ancestry, so its impact on the population level may be minimal.  link to online article

Genetic studies often identify multiple genetic variants associated with a particular outcome, and methods are need to help to identify real causal variants from among chance findings. A method called the preferential LD approach was tested in genetic data derived in four studies of breast cancer in African American women, including the BWHS. The results support the use of the preferential LD approach in African American women.  link to online article

Hypertension (high blood pressure) affects Black women more than other racial groups, and it increases the risk of heart disease, which is the leading cause of death in the U.S. In a study of breastfeeding and hypertension in the BWHS, we found that breastfeeding was associated with a reduced risk of hypertension at ages 40-49 years. Risk decreased as duration of breastfeeding increased. If confirmed, this adds to the list of reasons that it is good for the health of women (as well as their babies) for them to breastfeed.  link to online article

Aggressive subtypes of breast cancer, such as estrogen receptor negative (ER-) tumors, lead to higher breast cancer mortality and occur more commonly among Black women than among White women. Risk factors for ER- breast cancer are poorly understood. We assessed reproductive risk factors and body size in relation to the incidence of ER- and ER+ breast cancer in the BWHS. Higher parity (number of births) and older age at first birth were associated with increased risk of ER- breast cancer among women less than 45 years of age; breastfeeding reduced the risk associated with higher parity. Abdominal obesity (obesity around the waist as opposed to around the hips) was also associated with higher risk of ER- breast cancer among women under age 45. None of these factors was associated with ER+ breast cancer at older ages or with ER+ breast cancer. These findings indicate that risk factors vary by age and by breast cancer subtype, and that differences in reproductive factors may contribute to Black/White differences in the occurrence of aggressive forms of breast cancer.  link to online article

Air pollution levels can be measured with remote sensing devices or using ground-based information.  Both measures were associated with mortality in a large study of cancer,  but the effect estimates were generally larger when the ground-based information was used.  link to online article