In HER2(−) breast cancer patients, a weak, borderline correlation was found between tumor size and TSH (r = 0.25, P = 0.053), but not between tumor size and FT3 (r = −0.13, P = 0.35) or FT4 (r = 0.16, P = 0.22). Here, ERBB2 is linked to breast carcinoma.