Vohra Varun, Yesantharao Lekha V, Stemme Rachel, Seal Stella M, Morris-Wiseman Lilah F, McAdams-DeMarco Mara, Mady Leila J, Deziel Nicole C, Biswal Shyam, Ramanathan Murugappan, Mathur Aarti
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Welch Medical Library, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Thyroid. 2024 Dec;34(12):1451-1464. doi: 10.1089/thy.2024.0317. Epub 2024 Nov 18.
The global incidence of thyroid cancer has increased over the past several decades. While this increase is partially due to increased detection, environmental pollutants have also emerged as a possible contributing factor. Our goal was to perform a systematic review to assess the relationship between environmental air pollution and thyroid cancer. Systematic literature search was performed using PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases for original articles published prior to March 2024, investigating outdoor air pollution and thyroid cancer/nodules (PROSPERO CRD42024517624). Inclusion criteria included quantitative reporting of pollutant levels and effect size. Specific pollutants included ozone (O), particulate matter less than 2.5 (PM) or 10 microns in diameter (PM), sulfur dioxide (SO), nitric oxides (NO), carbon monoxide (CO), and polyaromatic hydrocarbons (PAHs). Study design, sample size, pollution assessment method, covariates, and strength/direction of associations between pollutants and thyroid cancer/nodule detection were extracted, and descriptive synthesis was utilized to summarize pertinent findings. Risk of bias was assessed using the National Heart, Lung, and Blood Institute quality assessment tool. Of 1294 identified studies, 11 met inclusion criteria. Over 6 million patients from diverse regions were represented across studies. Pollutants studied included O in 5 studies; PM, PM, SO, and NO in 3 studies; unspecified PM and CO in 2 studies; and PAHs in 1 study. Primary outcome was thyroid cancer diagnosis among 9 studies and thyroid nodule detection in 2. All studies examining NO and O reported increased risks ranging from 1.03 to 1.5-fold and 1.1 to 1.3-fold, respectively. Both studies assessing PM reported 1.18 to 1.23-fold increased odds of thyroid cancer diagnosis, and the magnitude of association increased with increasing duration or concentration of PM Inconsistent results were observed for levels of CO, PM, and SO. While an emerging body of literature suggests a potential association between air pollution and thyroid cancer, the quality of evidence is limited by study design constraints, variability in exposure assessment, and inconsistent adjustment for potential confounding factors. The heterogeneity in study designs and methodologies present challenges in interpreting results, underscoring the need for standardized approaches in future research.
在过去几十年中，全球甲状腺癌的发病率有所上升。虽然这种上升部分归因于检测手段的提高，但环境污染物也已成为一个可能的促成因素。我们的目标是进行一项系统综述，以评估环境空气污染与甲状腺癌之间的关系。我们使用PubMed、EMBASE、Cochrane图书馆、科学网和Scopus数据库，对2024年3月之前发表的关于室外空气污染与甲状腺癌/结节的原始文章进行了系统的文献检索（国际前瞻性系统评价注册库编号CRD42024517624）。纳入标准包括污染物水平和效应量的定量报告。具体污染物包括臭氧（O₃）、直径小于2.5微米（PM₂.₅）或10微米（PM₁₀）的颗粒物、二氧化硫（SO₂）、氮氧化物（NOₓ）、一氧化碳（CO）和多环芳烃（PAHs）。提取了研究设计、样本量、污染评估方法、协变量以及污染物与甲状腺癌/结节检测之间关联的强度/方向，并利用描述性综合分析来总结相关发现。使用美国国立心肺血液研究所的质量评估工具对偏倚风险进行了评估。在1294项已识别的研究中，有11项符合纳入标准。各项研究涵盖了来自不同地区的600多万患者。所研究的污染物中，有5项研究涉及O₃；3项研究涉及PM₂.₅、PM₁₀、SO₂和NOₓ；2项研究涉及未明确的PM和CO；1项研究涉及PAHs。9项研究的主要结局是甲状腺癌诊断，2项研究的主要结局是甲状腺结节检测。所有研究NOₓ和O₃的研究均报告风险增加，范围分别为1.03至1.5倍和1.1至1.3倍。两项评估PM₂.₅的研究均报告甲状腺癌诊断的几率增加了1.18至1.23倍，且关联强度随PM₂.₅持续时间或浓度的增加而增大。对于CO、PM₁₀和SO₂的水平，观察到了不一致的结果。虽然越来越多的文献表明空气污染与甲状腺癌之间可能存在关联，但证据质量受到研究设计限制、暴露评估的变异性以及对潜在混杂因素的不一致调整的限制。研究设计和方法的异质性给结果解释带来了挑战，凸显了未来研究中采用标准化方法的必要性。
