Department of Surgery, Skåne University Hospital Malmö, Malmö, Sweden.
Breast Cancer Res. 2010;12(3):R33. doi: 10.1186/bcr2587. Epub 2010 Jun 11.
The potential association between hypo- and hyperthyroid disorders and breast cancer has been investigated in a large number of studies during the last decades without conclusive results. This prospective cohort study investigated prediagnostic levels of thyrotropin (TSH) and triiodothyronine (T3) in relation to breast cancer incidence in pre- and postmenopausal women.
In the Malmö Preventive Project, 2,696 women had T3 and/or TSH levels measured at baseline. During a mean follow-up of 19.3 years, 173 incident breast cancer cases were retrieved using record linkage with The Swedish Cancer Registry. Quartile cut-points for T3 and TSH were based on the distribution among all women in the study cohort. A Cox's proportional hazards analysis was used to estimate relative risks (RR), with a confidence interval (CI) of 95%. Trends over quartiles of T3 and TSH were calculated considering a P-value < 0.05 as statistically significant. All analyses were repeated for pre- and peri/postmenopausal women separately.
Overall there was a statistically significant association between T3 and breast cancer risk, the adjusted RR in the fourth quartile, as compared to the first, was 1.87 (1.12 to 3.14). In postmenopausal women the RRs for the second, third and fourth quartiles, as compared to the first, were 3.26 (0.96 to 11.1), 5.53 (1.65 to 18.6) and 6.87 (2.09 to 22.6), (P-trend: < 0.001). There were no such associations in pre-menopausal women, and no statistically significant interaction between T3 and menopausal status. Also, no statistically significant association was seen between serum TSH and breast cancer.
This is the first prospective study on T3 levels in relation to breast cancer risk. T3 levels in postmenopausal women were positively associated with the risk of breast cancer in a dose-response manner.
在过去几十年的大量研究中，研究了甲状腺功能减退症和甲状腺功能亢进症与乳腺癌之间的潜在关联，但结果尚无定论。这项前瞻性队列研究调查了促甲状腺激素（TSH）和三碘甲状腺原氨酸（T3）在绝经前和绝经后妇女乳腺癌发病中的预测水平。
在马尔默预防项目中，2696 名女性在基线时测量了 T3 和/或 TSH 水平。在平均 19.3 年的随访期间，通过与瑞典癌症登记处的记录链接，检索到 173 例乳腺癌病例。T3 和 TSH 的四分位数切点基于研究队列中所有女性的分布。使用 Cox 比例风险分析估计相对风险（RR），置信区间（CI）为 95%。考虑到 P 值<0.05 为统计学显著，计算 T3 和 TSH 四分位区间的趋势。所有分析均针对绝经前和绝经后妇女分别进行重复。
总体而言，T3 与乳腺癌风险之间存在统计学显著关联，与第 1 四分位相比，第 4 四分位的调整 RR 为 1.87（1.12 至 3.14）。在绝经后妇女中，与第 1 四分位相比，第 2、3 和 4 四分位的 RR 分别为 3.26（0.96 至 11.1）、5.53（1.65 至 18.6）和 6.87（2.09 至 22.6），（P 趋势：<0.001）。在绝经前妇女中没有这种关联，T3 与绝经状态之间也没有统计学显著的交互作用。此外，血清 TSH 与乳腺癌之间也没有统计学显著的关联。
这是第一项关于 T3 水平与乳腺癌风险关系的前瞻性研究。绝经后妇女 T3 水平与乳腺癌风险呈剂量反应关系呈正相关。
