A study by Nagata et al. showed that the plasma levels of certain specific amino acids, such as Arg, Leu, Tyr, and Asp, were associated with endogenous sex hormone levels, sex-hormone-binding globulin (SHBG), or insulin-like growth factor (IGF-1), as determined by biomarkers of breast cancer risk [88]. Here, SHBG is linked to breast carcinoma.