Is there an association between thyroid function abnormalities and breast cancer?

ABSTRACT Objective The aim of this study was to evaluate the association between thyroid function abnormalities and breast cancer and, in particular, the prognostic markers of breast cancer.. Subjects and methods Baseline levels of thyrotropin, free triiodothyronine, free thyroxine and thyroid autoantibodies were measured in 97 women with primary breast cancer, 27 women with benign breast disease, and 4 women with atypical ductal hyperplasia. Their baseline levels were compared with those in 48 healthy women with a normal mammography in the last 2 years. Results There were no significant associations between history of thyroid disease and breast cancer (p = 0.33). The mean baseline levels of triiodothyronine and thyrotropin did not differ significantly between the compared groups. The mean baseline levels of free thyroxine were found to be significantly higher in the breast cancer group, even after adjusting for thyroid replacement therapy. The presence of thyroid antibodies did not differ significantly between the compared groups. In a subgroup analysis, breast cancer cases with thyroid disease and particularly hypothyroidism had a significantly lower incidence of lymph node metastases compared with breast cancer cases without thyroid disease. Conclusions Our data confirmed the proliferative effect of thyroid hormones on breast cells, which had previously been shown in vitro. Additionally, thyroid disease and particularly hypothyroid function appeared to be associated with a lower incidence of lymph node metastases. Further studies to determine the prognostic role of thyroid hormones in breast cancer are warranted.

摘要

研究目的：本研究旨在评估甲状腺功能异常与乳腺癌的关联，尤其是乳腺癌的预后标志物。

研究对象与方法：本研究分别检测了97例原发性乳腺癌（primary breast cancer）患者、27例乳腺良性疾病（benign breast disease）患者及4例导管上皮不典型增生（atypical ductal hyperplasia）患者的促甲状腺激素（thyrotropin）、游离三碘甲状腺原氨酸（free triiodothyronine）、游离甲状腺素（free thyroxine）及甲状腺自身抗体（thyroid autoantibodies）基线水平，并将上述指标与近2年内乳腺钼靶（mammography）检查正常的48名健康女性的对应基线水平进行对比。

研究结果：甲状腺疾病史与乳腺癌未呈现显著关联（p=0.33）。各对比组间的三碘甲状腺原氨酸与促甲状腺激素的基线平均水平无显著差异。即使在校正甲状腺激素替代治疗（thyroid replacement therapy）相关因素后，乳腺癌组的游离甲状腺素基线平均水平仍显著高于其他组别。各组间甲状腺自身抗体的检出率无显著差异。亚组分析显示，合并甲状腺疾病（尤其是甲状腺功能减退症）的乳腺癌患者，其淋巴结转移（lymph node metastases）发生率显著低于无甲状腺疾病的乳腺癌患者。

研究结论：本研究数据证实了甲状腺激素对乳腺细胞的增殖效应，这与既往体外（in vitro）研究的结果一致。此外，甲状腺疾病（尤其是甲状腺功能减退）似乎与较低的淋巴结转移发生率相关。未来需开展进一步研究以明确甲状腺激素在乳腺癌中的预后作用。