S100P calcium-binding protein expression is associated with high-risk proliferative lesions of the breast.

Benign breast diseases represent the vast majority of diagnosis in breast pathology. However, the limited capability in identifying lesions at high risk of breast cancer evolution is an increasing problem in clinical practice. In the present study, we tested the hypothesis that the overexpression of S100P calcium-binding protein, previously identified in the very early stages of breast carcinogenesis, could be used as a marker to differentiate lesions at high risk of malignant evolution. In addition to S100P, the well-known proliferative marker, Ki-67, and estrogen receptor (ER) status were also assessed by immunohistochemistry in 155 samples from patients who submitted to stereotactic vacuum-assisted core biopsy due to breast microcalcifications. Results showed a positive association between ER and S100P overexpression, as well as a clear positive association between S100P overexpression and high-risk lesions. The strong association between S100P and ER expression highlights the hypothesis about the possible role played by S100P in the very early stages of breast carcinogenesis.