Prospective evaluation of circulating plasma thyroid hormones concentrations and breast cancer risk in the EPIC cohort.

18 A fourth prospective study based on Australian participants (38% premenopausal), suggested a positive association with fT4 of borderline significance (OR per unit increase = 1.07 (0.99–1.17)), but included a more limited number of cases (n = 100). 15 Although one prospective study (n = 61 cases) reported higher breast cancer risk among postmenopausal women with low fT4 concentrations, 19 a recent, large Mendelian Randomisation analysis combining

also in 736 other papers