Preoperative serum MMP-9 immunoreactive protein is a prognostic indicator for relapse-free survival in breast carcinoma.

The immunoreactive protein for the matrix metalloproteinase-9 (MMP-9) was studied prospectively from the pre-treatment sera of breast carcinoma patients using an enzyme-linked immunoassay (ELISA). The study comprised 71 primary breast carcinoma patients treated in Oulu University Hospital, Finland, between 1988 and 1991. The median follow-up time was over 10 years. Low preoperative serum MMP-9 (<54.5 ng/ml) was found to correlate with a poor relapse-free survival (RFS) in primary breast carcinoma. After 10 years of follow-up only 43% of the patients with low serum MMP-9 were disease-free, whereas 76% of the patients with high serum MMP-9 lived free of the disease (log-rank P=0.008). Low serum MMP-9 also indicated poor RFS in node-negative (P=0.03), stage I-II (P=0.01), progesterone receptor negative (P=0.008) carcinoma as well as in patients <50 years (P=0.02) with primary breast carcinoma. There was no statistical difference in overall survival. In multivariate analysis, preoperative low serum MMP-9 increases the risk of relapse 3.0-fold during the first 10 years of follow-up in primary breast carcinoma.