BACKGROUND Environmental exposures are related to the risk of some types of cancer, and children are the most vulnerable group of people. This study seeks to present the methodological approaches used in the papers of our group about risk of childhood cancers in the vicinity of pollution sources (industrial and urban sites). A population-based case-control study of incident childhood cancers in Spain and their relationship with residential proximity to industrial and urban areas was designed. Two methodological approaches using mixed multiple unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) were developed: (a) "near vs. far" analysis, where possible excess risks of cancers in children living near ("near") versus those living far ("far") from industrial and urban areas were assessed; and (b) "risk gradient" analysis, where the risk gradient in the vicinity of industries was assessed. For each one of the two approaches, three strategies of analysis were implemented: "joint", "stratified", and "individualized" analysis. Incident cases were obtained from the Spanish Registry of Childhood Cancer (between 1996 and 2011). RESULTS Applying this methodology, associations between proximity (≤ 2 km) to specific industrial and urban zones and risk (OR; 95% CI) of leukemias (1.31; 1.04-1.65 for industrial areas, and 1.28; 1.00-1.53 for urban areas), neuroblastoma (2.12; 1.18-3.83 for both industrial and urban areas), and renal (2.02; 1.16-3.52 for industrial areas) and bone (4.02; 1.73-9.34 for urban areas) tumors have been suggested. CONCLUSIONS The two methodological approaches were used as a very useful and flexible tool to analyze the excess risk of childhood cancers in the vicinity of industrial and urban areas, which can be extrapolated and generalized to other cancers and chronic diseases, and adapted to other types of pollution sources.

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研究污染源附近癌症风险的方法论方法：基于人口的儿童癌症病例对照研究的经验。

背景技术环境暴露与某些类型的癌症风险有关，儿童是最脆弱的人群。这项研究旨在介绍在我们小组的论文中，有关污染源（工业和城市场所）附近儿童患癌症的风险的方法学方法。设计了一项基于人群的病例对照研究，研究西班牙儿童期癌症及其与居住在工业和城市地区附近的关系。开发了两种使用混合的多个无条件逻辑回归模型来估计比值比（OR）和95％置信区间（95％CI）的方法学方法：（a）“近距离与远距离”分析，在这种情况下，活着的儿童可能会患上癌症较近（“近”）与较远（“远”）的人 ）对工业和城市地区进行了评估；（b）“风险梯度”分析，其中评估了行业附近的风险梯度。对于这两种方法中的每一种，都实施了三种分析策略：“联合”，“分层”和“个性化”分析。事故病例来自西班牙儿童癌症登记处（1996年至2011年）。结果应用该方法，特定工业和城市地区的邻近度（≤2 km）与白血病的风险（OR； 95％CI）之间存在关联（1.31；工业区为1.04-1.65；城市区为1.28； 1.00-1.53​​）已经提出了神经母细胞瘤（对于工业和城市地区来说是2.12； 1.18-3.83），肾（对于工业地区来说是2.02； 1.16-3.52）和骨（对于城市地区是4.02； 1.73-9.34）肿瘤。