Abstract：
BACKGROUND: Air pollution has been classified as a human carcinogen based largely on findings for respiratory cancers. Emerging, but limited, evidence suggests that it increases the risk of breast cancer, particularly among younger women. We characterized associations between residential exposure to ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2) and breast cancer. Analyses were performed using data collected in the Ontario Environmental Health Study (OEHS).
METHODS: The OEHS, a population-based case-control study, identified incident cases of breast cancer in Ontario, Canada among women aged 18-45 between 2013 and 2015. A total of 465 pathologically confirmed primary breast cancer cases were identified from the Ontario Cancer Registry, while 242 population-based controls were recruited using random-digit dialing. Self-reported questionnaires were used to collect risk factor data and residential histories. Land-use regression and remote-sensing estimates of NO2 and PM2.5, respectively, were assigned to the residential addresses at interview, five years earlier, and at menarche. Logistic regression was used to estimate odds ratios (OR) and their 95 % confidence intervals (CI) in relation to an interquartile range (IQR) increase in air pollution, adjusting for possible confounders.
RESULTS: PM2.5 and NO2 were positively correlated with each other (r = 0.57). An IQR increase of PM2.5 (1.9 µg/m3) and NO2 (6.6 ppb) at interview residence were associated with higher odds of breast cancer and the adjusted ORs and 95 % CIs were 1.37 (95 % CI = 0.98-1.91) and 2.33 (95 % CI = 1.53-3.53), respectively. An increased odds of breast cancer was observed with an IQR increase in NO2 at residence five years earlier (OR = 2.16, 95 % CI: 1.41-3.31), while no association was observed with PM2.5 (OR = 0.96, 95 % CI 0.64-1.42).
CONCLUSIONS: Our findings support the hypothesis that exposure to ambient air pollution, especially those from traffic sources (i.e., NO2), increases the risk of breast cancer in young women.
METHODS: The OEHS, a population-based case-control study, identified incident cases of breast cancer in Ontario, Canada among women aged 18-45 between 2013 and 2015. A total of 465 pathologically confirmed primary breast cancer cases were identified from the Ontario Cancer Registry, while 242 population-based controls were recruited using random-digit dialing. Self-reported questionnaires were used to collect risk factor data and residential histories. Land-use regression and remote-sensing estimates of NO2 and PM2.5, respectively, were assigned to the residential addresses at interview, five years earlier, and at menarche. Logistic regression was used to estimate odds ratios (OR) and their 95 % confidence intervals (CI) in relation to an interquartile range (IQR) increase in air pollution, adjusting for possible confounders.
RESULTS: PM2.5 and NO2 were positively correlated with each other (r = 0.57). An IQR increase of PM2.5 (1.9 µg/m3) and NO2 (6.6 ppb) at interview residence were associated with higher odds of breast cancer and the adjusted ORs and 95 % CIs were 1.37 (95 % CI = 0.98-1.91) and 2.33 (95 % CI = 1.53-3.53), respectively. An increased odds of breast cancer was observed with an IQR increase in NO2 at residence five years earlier (OR = 2.16, 95 % CI: 1.41-3.31), while no association was observed with PM2.5 (OR = 0.96, 95 % CI 0.64-1.42).
CONCLUSIONS: Our findings support the hypothesis that exposure to ambient air pollution, especially those from traffic sources (i.e., NO2), increases the risk of breast cancer in young women.
摘要：
背景：空气污染已被归类为人类致癌物，主要基于呼吸道癌症的发现。新兴，但有限，证据表明它增加了患乳腺癌的风险，尤其是年轻女性。我们表征了居民暴露于环境细颗粒物（PM2.5）和二氧化氮（NO2）与乳腺癌之间的关联。使用安大略省环境健康研究（OEHS）中收集的数据进行分析。
方法：OEHS，一项基于人群的病例对照研究，安大略省确定的乳腺癌事件，加拿大在2013年至2015年期间的18-45岁女性中。从安大略省癌症登记处共发现465例经病理证实的原发性乳腺癌病例。而使用随机数字拨号招募了242名基于人群的对照组.使用自我报告问卷收集风险因素数据和居住历史。分别对NO2和PM2.5的土地利用回归和遥感估算，在面试时被分配到住址，五年前,在初潮时。使用逻辑回归来估计与空气污染的四分位数间距（IQR）增加有关的比值比（OR）及其95％置信区间（CI）。调整可能的混杂因素。
结果：PM2.5与NO2呈正相关(r=0.57)。在访谈居住地，PM2.5（1.9µg/m3）和NO2（6.6ppb）的IQR增加与乳腺癌的几率更高相关，校正后的OR和95％CI分别为1.37（95％CI=0.98-1.91）和2.33（95％CI=1.53-3.53），分别。在居住五年前，NO2的IQR增加，观察到乳腺癌的几率增加（OR=2.16，95％CI：1.41-3.31），而与PM2.5无相关性（OR=0.96，95%CI0.64-1.42）。
结论：我们的研究结果支持以下假设：暴露于环境空气污染，尤其是那些来自交通来源的(即，NO2),增加年轻女性患乳腺癌的风险。
方法：OEHS，一项基于人群的病例对照研究，安大略省确定的乳腺癌事件，加拿大在2013年至2015年期间的18-45岁女性中。从安大略省癌症登记处共发现465例经病理证实的原发性乳腺癌病例。而使用随机数字拨号招募了242名基于人群的对照组.使用自我报告问卷收集风险因素数据和居住历史。分别对NO2和PM2.5的土地利用回归和遥感估算，在面试时被分配到住址，五年前,在初潮时。使用逻辑回归来估计与空气污染的四分位数间距（IQR）增加有关的比值比（OR）及其95％置信区间（CI）。调整可能的混杂因素。
结果：PM2.5与NO2呈正相关(r=0.57)。在访谈居住地，PM2.5（1.9µg/m3）和NO2（6.6ppb）的IQR增加与乳腺癌的几率更高相关，校正后的OR和95％CI分别为1.37（95％CI=0.98-1.91）和2.33（95％CI=1.53-3.53），分别。在居住五年前，NO2的IQR增加，观察到乳腺癌的几率增加（OR=2.16，95％CI：1.41-3.31），而与PM2.5无相关性（OR=0.96，95%CI0.64-1.42）。
结论：我们的研究结果支持以下假设：暴露于环境空气污染，尤其是那些来自交通来源的(即，NO2),增加年轻女性患乳腺癌的风险。
