Abstract
BackgroundExposure to road traffic noise was associated with increased risk of estrogen receptor (ER)-negative (ER-) breast cancer in a previous cohort study, but not with overall or ER-positive (ER+) breast cancer, or breast cancer prognosis. We examined the association between long-term exposure to road traffic noise and incidence of breast cancer, overall and by ER and progesterone receptor (PR) status.MethodsWe used the data from a nationwide Danish Nurse Cohort on 22,466 female nurses (age > 44 years) who at recruitment in 1993 or 1999 reported information on breast cancer risk factors. We obtained data on the incidence of breast cancer from the Danish Cancer Registry, and on breast cancer subtypes by ER and PR status from the Danish Breast Cancer Cooperative Group, up to 31 December 2012. Road traffic noise levels at the nurses’ residences were estimated by the Nord2000 method between 1970 and 2013 as annual means of a weighted 24 h average (Lden) at the most exposed facade. We used time-varying Cox regression to analyze the associations between the 24-year, 10-year, and 1-year mean of Lden and breast cancer, separately for total breast cancer and by ER and PR status.ResultsOf the 22,466 women, 1193 developed breast cancer in total during 353,775 person-years of follow up, of whom 611 had complete information on ER and PR status. For each 10 dB increase in 24-year mean noise levels at their residence, we found a statistically significant 10% (hazard ratio and 95% confidence interval 1.10; 1.00–1.20) increase in total breast cancer incidence and a 17% (1.17; 1.02–1.33) increase in analyses based on 611 breast cancer cases with complete ER and PR information. We found positive, statistically significant association between noise levels and ER+ (1.23; 1.06–1.43, N = 494) but not ER- (0.93; 0.70–1.25, N = 117) breast cancers, and a stronger association between noise levels and PR+ (1.21; 1.02–1.42, N = 393) than between noise levels and PR- (1.10; 0.89–1.37, N = 218) breast cancers. Association between noise and ER+ breast cancer was statistically significantly stronger in nurses working night shifts (3.36; 1.48–7.63) than in those not working at night (1.21; 1.02–1.43) (p value for interaction = 0.05).ConclusionLong-term exposure to road traffic noise may increase risk of ER+ breast cancer.
Highlights
Exposure to road traffic noise was associated with increased risk of estrogen receptor (ER)-negative (ER-) breast cancer in a previous cohort study, but not with overall or ER-positive (ER+) breast cancer, or breast cancer prognosis
Additional sensitivity analyses included analyses of association between 24-year mean Lden and overall breast cancer (BC) with additional adjustment for the baseline year, mean income at the municipality of residence at the cohort baseline, as a proxy of neighborhood socio-economic level, and air pollution, in terms of particulate matter (PM) less than 2.5 nm, (PM2.5) and nitrogen oxide (NOx) at the baseline year We did not adjust for air pollution in the main model, since air pollution is still not recognized as a risk factor for BC, and since we have previously found no association between air pollution and BC in this cohort [37]
In the fully adjusted models, we found a positive and statistically significant association between each 10 dB increase in residential road traffic noise levels at the residence (24-year mean noise levels preceding diagnosis) and incidence of BC, ranging from a 10% (HR; 95% confidence intervals (CI), 1.10; 1.00–1.20) increase in total BC incidence (N = 1193), to a 17% (HR; 95% CI, 1.17; 1.02–1.33) increase in incidence based on the 611 BC cases with ER and progesterone receptor (PR) information (Table 2)
Summary
Exposure to road traffic noise was associated with increased risk of estrogen receptor (ER)-negative (ER-) breast cancer in a previous cohort study, but not with overall or ER-positive (ER+) breast cancer, or breast cancer prognosis. In a single controlled experimental study in 18 healthy subjects, exposure to residential road traffic noise (48 or 75 dB) has been shown to result in increased levels of gene expression biomarkers of oxidative stress and DNA repair [12]. Oxidative stress promotes BC development and progression [14, 15] and one study suggests that this mechanism is most relevant for estrogen receptor (ER)-positive (ER+) BC [15]. Another mechanism behind the possible link between noise exposure and BC involves sleep disturbance, reduced sleep quality and duration, which have been linked to residential road traffic noise exposure at night [16, 17]. Exposure to residential road traffic noise may increase the risk of weight gain [24], obesity [25, 26], and type II diabetes mellitus [27], all risk factors for postmenopausal BC [28, 29]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
