Ambient fine particulate matter and breast cancer incidence in a large prospective US cohort.

BACKGROUND: Fine particulate matter (PM2.5) has been inconsistently associated with breast cancer incidence, however, few studies have considered historic exposure when levels were higher. METHODS: Outdoor residential PM2.5 concentrations were estimated using a nationwide spatiotemporal model for women in the National Institutes of Health-AARP Diet and Health Study, a prospective cohort located in 6 states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and 2 metropolitan areas (Atlanta, GA, and Detroit, MI) and enrolled in 1995-1996 (n = 196 905). Annual average PM2.5 concentrations were estimated for a 5-year historical period 10 years prior to enrollment (1980-1984). We used Cox regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between a 10 µg/m3 increase in PM2.5 and breast cancer incidence overall and by estrogen receptor status and catchment area. RESULTS: With follow-up of participants through 2017, a total of 15 870 breast cancer cases were identified. A 10 ug/m3 increase in PM2.5 was statistically significantly associated with overall breast cancer incidence (HR = 1.08, 95% CI = 1.02 to 1.13). The association was evident for estrogen receptor-positive (HR = 1.10, 95% CI = 1.04 to 1.17) but not estrogen receptor-negative tumors (HR = 0.97, 95% CI = 0.84 to 1.13; Pheterogeneity = .3). Overall breast cancer hazard ratios were more than 1 across the catchment areas, ranging from a hazard ratio of 1.26 (95% CI = 0.96 to 1.64) for North Carolina to a hazard ratio of 1.04 (95% CI = 0.68 to 1.57) for Louisiana (Pheterogeneity = .9). CONCLUSIONS: In this large US cohort with historical air pollutant exposure estimates, PM2.5 was associated with risk of estrogen receptor-positive breast cancer. State-specific estimates were imprecise but suggest that future work should consider region-specific associations and the potential contribution of PM2.5 chemical constituency in modifying the observed association.

Light at night and the risk of breast cancer: Findings from the Sister study.

BACKGROUND: Light at night (LAN) may alter estrogen regulation through circadian disruption. High levels of outdoor LAN may increase breast cancer risk, but studies have largely not considered possible residual confounding from correlated environmental exposures. We evaluated the association between indoor and outdoor LAN and incident breast cancer. METHODS: In 47,145 participants in the prospective Sister Study cohort living in the contiguous U.S., exposure to outdoor LAN was determined using satellite-measured residential data and indoor LAN was self-reported (light/TV on, light from outside the room, nightlight, no light). We used Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between outdoor and indoor LAN and breast cancer risk. Models were adjusted for age, race/ethnicity, educational attainment, annual household income, neighborhood disadvantage, latitude, and population density as a proxy for urbanicity. To evaluate the potential for residual confounding of the outdoor LAN and breast cancer relationship by factors associated with urbanicity, we considered further adjustment for exposures correlated with outdoor LAN including NO2 [Spearman correlation coefficient, rho (ρ) = 0.78], PM2.5 (ρ = 0.36), green space (ρ =  - 0.41), and noise (ρ = 0.81). RESULTS: During 11 years of follow-up, 3,734 breast cancer cases were identified. Outdoor LAN was modestly, but non-monotonically, associated with a higher risk of breast cancer (Quintile 4 vs 1: HR = 1.10, 95% CI: 0.99-1.22; Quintile 5 vs 1: HR = 1.04, 95% CI: 0.93-1.16); however, no association was evident after adjustment for correlated ambient exposures (Quintile 4 vs 1: HR = 0.99, 95% CI: 0.86-1.14; Quintile 5 vs 1: HR = 0.89, 95% CI: 0.74-1.06). Compared to those with no indoor LAN exposure, sleeping with a light or TV on was associated with a HR = 1.09 (95% CI: 0.97-1.23) in the adjusted model. CONCLUSIONS: Outdoor LAN does not appear to increase the risk of breast cancer after adjustment for correlated environmental exposures.

Shift Work and Working at Night in Relation to Breast Cancer Incidence.

BACKGROUND: Night shift work has been classified by the International Agency for Research on Cancer as a probable carcinogen in humans. Several studies have assessed night shift work in relation to breast cancer risk, with inconsistent results. METHODS: In the prospective Sister Study cohort, current and past occupational history was collected for 48,451 participants. We used Cox proportional hazards models to estimate adjusted HRs and 95% confidence intervals (CI) for the association between baseline work schedule characteristics and incident breast cancer. RESULTS: During follow-up (mean = 9.1 years), 3,191 incident cases were diagnosed. We observed little to no increase in risk associated with work schedule characteristics (ever working rotating shifts: HR = 1.04, 95% CI, 0.91-1.20; ever working rotating night shifts: HR = 1.08, 95% CI, 0.92-1.27; ever working at night: HR = 1.01, 95% CI, 0.94-1.10; and ever working irregular hours: HR = 0.98, 95% CI, 0.91-1.06). Although short-term night work (>0 to 5 years vs. never: HR = 1.12; 95% CI, 1.00-1.26) and rotating shift work at night (>0 to 5 years vs. never: HR = 1.30; 95% CI, 1.05-1.61) were associated with increased breast cancer risk, working nights for more than 5 years was not associated with risk. CONCLUSIONS: Overall, we observed little evidence that rotating shift work or work at night was associated with a higher risk of breast cancer, except possibly among those who participated in such work for short durations of time. IMPACT: This study indicates that if night shift work is associated with breast cancer, the increase in risk is small.

Integrating biology and access to care in addressing breast cancer disparities: 25 years' research experience in the Carolina Breast Cancer Study.

PURPOSE OF REVIEW: To review research on breast cancer mortality disparities, emphasizing research conducted in the Carolina Breast Cancer Study, with a focus on challenges and opportunities for integration of tumor biology and access characteristics across the cancer care continuum. RECENT FINDINGS: Black women experience higher mortality following breast cancer diagnosis, despite lower incidence compared to white women. Biological factors, such as stage at diagnosis and breast cancer subtypes, play a role in these disparities. Simultaneously, social, behavioral, environmental, and access to care factors are important. However, integrated studies of biology and access are challenging and it is uncommon to have both data types available in the same study population. The central emphasis of Phase 3 of the Carolina Breast Cancer Study, initiated in 2008, was to collect rich data on biology (including germline and tumor genomics and pathology) and health care access in a diverse study population, with the long term goal of defining intervention opportunities to reduce disparities across the cancer care continuum. SUMMARY: Early and ongoing research from CBCS has identified important interactions between biology and access, leading to opportunities to build greater equity. However, sample size, population-specific relationships among variables, and complexities of treatment paths along the care continuum pose important research challenges. Interdisciplinary teams, including experts in novel data integration and causal inference, are needed to address gaps in our understanding of breast cancer disparities.

Medical Conditions and Modifiable Risk Factors for Myelodysplastic Syndrome: A Systematic Review.

BACKGROUND: The aim of this systematic review was to evaluate medical conditions and modifiable risk factors for myelodysplastic syndromes (MDS) using the 2001 or 2008 World Health Organization (WHO) diagnostic criteria. METHODS: PubMed, MEDLINE, and Scopus databases were searched for studies published between January 2001 and August 2017. Study characteristics and findings were abstracted for each article. RESULTS: Thirteen articles (4 cohort, 9 case-control) met the inclusion criteria. Smoking and alcohol use were each evaluated as potential MDS risk factors in four studies. Body mass index and anemia were each evaluated in two studies. Other potential risk factors evaluated in single studies included physical activity, dietary intake (tea, isoflavones, meat, fruit, or vegetables), history of allergies, autoimmune disorders and community-acquired infections, and use of antituberculosis drugs, traditional Chinese medicines, or hair dyes. CONCLUSIONS: Higher BMI, smoking, a history of autoimmune disorders, community-acquired infections, history of anemia, and use of antituberculosis drugs were associated with higher risk of MDS. Vigorous physical activity and tea and dietary isoflavone intake were associated with lower MDS risk. These findings suggest no association between the other factors and risk of MDS. IMPACT: Research on risk factors for MDS is limited, and further research in larger studies is needed.