Prognostic Significance of Immunoreactive Neutrophil Elastase in Human Breast Cancer: Long-Term Follow-Up Results in 313 Patients

OBJECTIVE: We have measured the concentration of immunoreactive neutrophil elastase (ir-NE) in the tumor extracts of 313 primary human breast cancers. Sufficient time has elapsed, and we are now ready to analyze its prognostic value in human breast cancer. METHODS: ir-NE concentration in tumor extracts was determined with an enzyme-linked immunosorbent assay that enables a rapid measurement of both free-form ir-NE and the α1-protease inhibitor-complexed form of ir-NE. We analyzed the prognostic value of this enzyme in human breast cancer in univariate and multivariate analyses. RESULTS: Patients with breast cancer tissue containing a high concentration of ir-NE had poor survival compared to those with a low concentration of ir-NE at the cutoff point of 9.0 µg/100 mg protein (P = .0012), which had been previously determined in another group of 49 patients. Multivariate stepwise analysis selected lymph node status (P= .0004; relative risk = 1.46) and ir-NE concentration (P= .0013; relative risk = 1.43) as independent prognostic factors for recurrence. CONCLUSIONS: Tumor ir-NE concentration is an independent prognostic factor in patients with breast cancer who undergo curative surgery. This enzyme may play an active role in tumor progression that leads to metastasis in human breast cancer.