OBJECTIVETo study the effects of aromatase on breast cancer proliferation and invasive ability, so as to detect the relationship between in situ estrogen levels and molecular biological characteristics of breast cancer.

METHODSBy immunohistochemistry staining, the expression of aromatase, matrix metalloproteinases 2 (MMP2) and matrix metalloproteinases (MMP 9) in the primary breast cancers were detected, the associations between aromatase and MMPs as well as clinical-pathological factors were analyzed.

RESULTSThe positive rates of aromatase were 25.0% (+) and 29.9% (++). Aromatase status was associated with MMP2, MMP9 and co-expression of MMP2 and MMP9 (P < 0.05), but not associated with tumor size, ER/PR status, menopausal status and tumor grade (P > 0.05). In the postmenopausal patients there was a relationship between aromatase and tumor size (P < 0.05), but not in the premenopausal patients (P > 0.05); there was a relationship between aromatase and co-expression of MMP2/MMP9 in the patients with ER and/or PR positive (P < 0.05), but not in the patients with ER and PR negative (P > 0.05).

CONCLUSIONSIn the breast cancer in situ estrogen produced by tumor aromatase may promote the cancer cells proliferation and invasiveness and maybe through ER pathway especially in the postmenopausal patients.