The Ca2+-binding protein S100 was first reported in 1965, followed by the discovery of >20 members of the protein family since then.2 Some of the S100s have been extensively shown to play a pivotal role in the onset and progression of malignant tumors, and certain S100 family members have also recently been reported to be related to multiple tumors, such as ovarian and breast cancer.3,4 Therefore, the level of the S100s might predict the HCC grade and stage, although this possibility has not been reported to date. Here, S100B is linked to breast cancer.