Furthermore, subgroup analysis showed that, in HER2(+) breast cancer patients, there was no correlation between tumor size and FT3 (r = −0.15 and P = 0.54), FT4 (r = 0.01 and P = 0.99), or TSH (r = −0.21 and P = 0.37). This evidence concerns the gene ERBB2 and breast carcinoma.