Department of Surgery, University and Regional Laboratories Region Skåne, Skåne University Hospital Malmö, Lund University, Malmö, Sweden.
Eur J Endocrinol. 2013 Mar 15;168(4):483-90. doi: 10.1530/EJE-12-0564. Print 2013 Apr.
The potential association between thyroid hormones and breast cancer has been investigated in a large number of studies without conclusive results. This study investigated triiodothyronine (T3) levels in relation to breast cancer mortality in a population with no breast cancer patients at baseline. An additional aim was to study T3 levels in relation to mortality from other cancers and all-cause mortality.
This was a population-based prospective cohort study including 2185 women in whom T3 levels were measured as part of a preventive health project, i.e. before diagnosis in women who later developed breast cancer. Mean follow-up was 24.1 years and record-linkage to The Swedish Cause-of-Death registry identified 471 women who died: 26 out of breast cancer and 182 from other cancers. Mortality was assessed using a Cox's analysis, yielding hazard ratios (HRs), with 95% confidence intervals. Analyses of T3 as a continuous variable were repeated for pre- and peri/postmenopausal women separately.
T3 levels were positively associated with the risk of breast cancer-specific death in the age-adjusted analysis: HR for T3 as a continuous variable was 2.80 (1.26-6.25). However, the crude analysis did not reach statistical significance. Breast cancer mortality was even higher in postmenopausal women: 3.73 (1.69-8.22), but stratified analyses included few events. There were no statistically significant associations between T3 levels and deaths from other cancers, age-adjusted HR: 1.09 (0.72-1.65) or all-cause mortality (1.25:0.97-1.60).
This study, the first of its kind on prospectively measured T3 levels, indicates that T3 levels are positively associated with breast cancer-specific mortality and that this is not related to a general effect on all-cause mortality.
大量研究调查了甲状腺激素与乳腺癌之间的潜在关联，但结果尚无定论。本研究在一个基线时无乳腺癌患者的人群中，调查了三碘甲状腺原氨酸（T3）水平与乳腺癌死亡率之间的关系。另一个目的是研究 T3 水平与其他癌症死亡率和全因死亡率之间的关系。
这是一项基于人群的前瞻性队列研究，包括 2185 名女性，她们的 T3 水平是作为预防健康项目的一部分进行测量的，即在后来患有乳腺癌的女性被诊断之前。平均随访时间为 24.1 年，通过与瑞典死因登记处的记录链接，确定了 471 名女性死亡：26 人死于乳腺癌，182 人死于其他癌症。使用 Cox 分析评估死亡率，得出风险比（HR）和 95%置信区间。对 T3 作为连续变量的分析分别在绝经前和绝经后妇女中重复进行。
在年龄调整分析中，T3 水平与乳腺癌特异性死亡风险呈正相关：T3 作为连续变量的 HR 为 2.80（1.26-6.25）。然而，原始分析未达到统计学意义。绝经后妇女的乳腺癌死亡率甚至更高：3.73（1.69-8.22），但分层分析纳入的事件较少。T3 水平与其他癌症死亡率或全因死亡率之间无统计学显著相关性（调整后 HR：1.09（0.72-1.65）或 1.25：0.97-1.60）。
这项研究是首例前瞻性测量 T3 水平的研究，表明 T3 水平与乳腺癌特异性死亡率呈正相关，且与全因死亡率的普遍影响无关。
