Expression of matrix metalloproteinase-9 in prostate cancer. Preliminary experience.

Objectives: To study the validity of Matrix Metalloproteinase 9 as a complementary marker to PSA for the diagnosis and prognosis of Prostate Cancer.

Methods: Prospective study structured as a hospital-based cohort of 100 consecutive patients undergoing prostate biopsy. Serum determination of MMP-9 was carried out by means of inmunoassay. Statistical analysis was performed using the Stata/SE 8.2 software.

Results: 32 patients were diagnosed with prostate cancer and 52% had a Gleason score equal to or greater than 7. The values of serum MMP-9 varied between 225.7 and 1932.3 ng/ml, without significant differences among patients with benign, malignant and uncertain histology (p=0.429). The differences approached statistical significance in the subgroup of patients with PSA at 4-10 ng/ml (p=0.058), and significant differences were observed in the subgroup with free PSA to total PSA coefficient of less than 15% (p=0.037). No relationship between the Gleason score and the level of MMP-9 was shown (p=0.739). The levels of PSA and MMP-9 were shown to be independent (Pearson coefficient of correlation -0.1).

Conclusions: It was not possible to show the efficacy of MMP-9 in predicting the result of the biopsy. In the group of patients with slightly increased levels of PSA (between 4 and 10 ng/ml) all the descriptive variables were higher in the group with malignant histology, though they did not reach statistical significance, they did reach significance when the coefficient of free PSA over total PSA was less than 15%, but this finding is not relevant clinically, as these patients already have a clear indication for biopsy. Neither was the relationship with the prognosis shown as there are no differences of MMP-9 expression at varying Gleason scores.