Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA.
Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA.
Environ Res. 2018 Aug;165:125-132. doi: 10.1016/j.envres.2018.04.012. Epub 2018 Apr 23.
Polychlorinated biphenyls (PCBs) and organochlorine pesticides have been associated with altered thyroid hormone levels in humans, but their relationship with thyroid cancer is unknown.
We conducted a nested case-control study of thyroid cancer in the Norwegian Janus Serum Bank cohort using pre-diagnostic blood samples from 1972 to 1985. Incident thyroid cancer (n = 108) was ascertained through 2008. Controls were matched 2:1 by age, date of blood draw, gender, and county. We used gas chromatography/mass spectrometry to quantify 36 PCB congeners and metabolites of pesticides DDT, chlordane, hexachlorocyclohexane, and hexachlorobenzene. PCBs and pesticide metabolites were evaluated individually and summed by degree of chlorination and parent compound, respectively. Odds ratios (OR) and 95% confidence intervals (CI) were computed using conditional logistic regression per specified increase in lipid-adjusted concentration. We additionally stratified analyses by birth cohort (1923-1932, 1933-1942, 1943-1957).
Increasing concentration of DDT metabolites (OR = 0.80, 95%CI = 0.66-0.98) was inversely associated with thyroid cancer. Associations for PCBs were null or in inverse direction. We observed interactions for total PCBs, moderately-chlorinated PCBs, and chlordane metabolites with birth cohort (p ≤ 0.04). Among participants born 1943-1957, total PCBs (OR = 1.25, 95%CI = 1.00-1.56), moderately-chlorinated PCBs (OR = 1.31, 95%CI = 1.01-1.70), and chlordane metabolites (OR = 1.78, 95%CI = 1.09-2.93) were positively associated with thyroid cancer. For individuals born before 1943, associations were generally null or in the inverse direction.
Emissions of PCBs and OC pesticides varied over time. Different risk patterns by birth cohort suggest the potential importance of timing of exposure in thyroid cancer risk. Further evaluation of these associations is warranted.
多氯联苯 (PCBs) 和有机氯农药已被证实与人类甲状腺激素水平改变有关，但它们与甲状腺癌的关系尚不清楚。
我们使用 1972 年至 1985 年的前瞻性病例对照研究，对挪威雅努斯血清库队列中的甲状腺癌进行了嵌套病例对照研究。通过 2008 年确定了甲状腺癌（n=108）的发病情况。根据年龄、采血日期、性别和郡对病例进行了 2:1 的配对。我们使用气相色谱/质谱法对 36 种多氯联苯同系物和杀虫剂滴滴涕、氯丹、六氯环己烷和六氯苯的代谢物进行了定量分析。分别按氯化度和母体化合物对多氯联苯和农药代谢物进行个体评估和求和。使用条件逻辑回归，根据特定的脂质校正浓度增加计算比值比（OR）和 95%置信区间（CI）。我们还按出生队列（1923-1932 年、1933-1942 年、1943-1957 年）对分析结果进行了分层。
滴滴涕代谢物浓度的升高（OR=0.80，95%CI=0.66-0.98）与甲状腺癌呈负相关。多氯联苯的相关性为零或呈反向。我们观察到总多氯联苯、中度氯化多氯联苯和氯丹代谢物与出生队列之间存在交互作用（p≤0.04）。在 1943-1957 年出生的参与者中，总多氯联苯（OR=1.25，95%CI=1.00-1.56）、中度氯化多氯联苯（OR=1.31，95%CI=1.01-1.70）和氯丹代谢物（OR=1.78，95%CI=1.09-2.93）与甲状腺癌呈正相关。对于 1943 年以前出生的个体，相关性通常为零或呈反向。
PCBs 和 OC 农药的排放量随时间而变化。按出生队列的不同风险模式表明，接触时间在甲状腺癌风险中的潜在重要性。需要进一步评估这些关联。
