The authors measured CCL2 serum levels in 135 patients with BC, 30 with DCIS I–III, and 143 with benign breast lesions and in 27 healthy women and examined whether the value of CCL2 serum levels can serve as a differentiation marker between malignant, preinvasive and benign breast diseases and as a predictive marker for the biological phenotype of BC. This evidence concerns the gene CCL2 and ductal breast carcinoma in situ.