Plasma matrix metalloproteinase 1, 3, and 7 levels and breast cancer risk in the Nurses' Health study.

PURPOSE: Matrix metalloproteinases (MMPs), in particular MMP1, 3, and 7, are believed to be critical to breast cancer invasion and metastasis and also may have important functions earlier in breast carcinogenesis. However, the relationship between circulating levels of MMP1, 3, and 7 and breast cancer risk is uncertain. METHODS: We examined associations between plasma MMP1, 3, and 7 and breast cancer risk in a prospective case-control study nested within the Nurses' Health Study. Blood samples were collected from 801 cases who developed breast cancer between 1992 and 2000 and 801 matched controls, and MMP levels were measured via immunofluorescence assay. RESULTS: No overall association was observed between any of these MMPs and breast cancer risk [top vs. bottom quintile; MMP1: odds ratio (OR) 0.9; 95 % confidence interval (CI) 0.7, 1.3; p-trend = 0.51; MMP3: OR 1.1; 95 % CI 0.8, 1.5; p-trend = 0.88; MMP7: OR = 1.2; 95 % CI 0.8, 1.7; p-trend = 0.18]. Further, findings did not significantly vary by time since blood draw, body mass index, or postmenopausal hormone use, or by breast cancer subtypes. CONCLUSIONS: Circulating MMP1, 3, and 7 levels do not appear to be predictive of overall breast cancer risk.