Epidemiology of radiation Group, Center for Research in Epidemiology and Population Health, INSERM U1018, Paris Sud-Paris Saclay University, Villejuif, France.
Inequalities in Cancer Outcomes Network, Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
Cancer Med. 2021 Jul;10(13):4604-4614. doi: 10.1002/cam4.3978. Epub 2021 May 26.
This study aimed to evaluate the association between thyroid dysfunction and breast cancer risk. We included 239,436 females of the UK Biobank cohort. Information on thyroid dysfunction, personal and family medical history, medications, reproductive factors, lifestyle, and socioeconomic characteristics was retrieved from baseline self-reported data and hospital inpatient databases. Breast cancer diagnoses were identified through population-based registries. We computed Cox models to estimate hazard ratios (HRs) of breast cancer incidence for thyroid dysfunction diagnosis and treatments, and examined potential confounding and effect modification by comorbidities and breast cancer risk factors. In our study, 3,227 (1.3%) and 20,762 (8.7%) women had hyper- and hypothyroidism prior to the baseline. During a median follow-up of 7.1 years, 5,326 (2.2%) women developed breast cancer. Compared to no thyroid dysfunction, there was no association between hypothyroidism and breast cancer risk overall (HR = 0.93, 95% confidence interval (CI): 0.84-1.02, 442 cases), but we found a decreased risk more than 10 years after hypothyroidism diagnosis (HR=0.85, 95%CI 0.74-0.97, 226 cases). There was no association with hyperthyroidism overall (HR=1.08, 95%CI 0.86-1.35, 79 cases) but breast cancer risk was elevated among women with treated hyperthyroidism (HR=1.38, 95%CI: 1.03-1.86, 44 cases) or aged 60 years or more at hyperthyroidism diagnosis (HR=1.74, 95%CI: 1.01-3.00, 113 cases), and 5-10 years after hyperthyroidism diagnosis (HR=1.58, 95%CI: 1.06-2.33, 25 cases). In conclusion, breast cancer risk was reduced long after hypothyroidism diagnosis, but increased among women with treated hyperthyroidism. Future studies are needed to determine whether the higher breast cancer risk observed among treated hyperthyroidism could be explained by hyperthyroidism severity, type of treatment or aetiology.
本研究旨在评估甲状腺功能障碍与乳腺癌风险之间的关联。我们纳入了英国生物库队列中的 239436 名女性。甲状腺功能障碍、个人和家族病史、药物使用、生育因素、生活方式和社会经济特征等信息均来自基线自我报告数据和医院住院数据库。乳腺癌诊断通过人群登记处确定。我们计算了 Cox 模型来估算甲状腺功能障碍诊断和治疗与乳腺癌发病率的风险比（HR），并通过合并症和乳腺癌危险因素检查了潜在的混杂因素和效应修饰作用。在本研究中，3227（1.3%）和 20762（8.7%）名女性在基线前患有甲状腺功能亢进症和甲状腺功能减退症。在中位随访 7.1 年期间，5326（2.2%）名女性发生了乳腺癌。与无甲状腺功能障碍相比，整体上甲状腺功能减退症与乳腺癌风险之间没有关联（HR=0.93，95%置信区间（CI）：0.84-1.02，442 例），但我们发现甲状腺功能减退症诊断 10 年以上后风险降低（HR=0.85，95%CI 0.74-0.97，226 例）。整体上与甲状腺功能亢进症无关（HR=1.08，95%CI 0.86-1.35，79 例），但治疗性甲状腺功能亢进症女性的乳腺癌风险升高（HR=1.38，95%CI：1.03-1.86，44 例）或甲状腺功能亢进症诊断时年龄为 60 岁或以上（HR=1.74，95%CI：1.01-3.00，113 例），以及甲状腺功能亢进症诊断后 5-10 年（HR=1.58，95%CI：1.06-2.33，25 例）。总之，甲状腺功能减退症诊断后乳腺癌风险降低，但治疗性甲状腺功能亢进症女性的风险增加。需要进一步研究以确定在治疗性甲状腺功能亢进症中观察到的更高乳腺癌风险是否可以通过甲状腺功能亢进症的严重程度、治疗类型或病因来解释。
