Cathepsin D concentration in primary laryngeal cancer: correlation with clinico-pathological parameters, EGFR status and prognosis

Sixty-three patients with primary laryngeal squamous-cell carcinoma were followed up for a median of 33 months after surgery. Cathepsin D (Cath D) concentration was assayed using a solid phase 2-site immunoradiometric assay in which the first monoclonal antibody (MAb) was coated on the ELISA solid phase and the second one, MIG8 radiolabeled with 1125-EGF, was used as the tracer. The median value of Cath D (13.8 pM/mg protein) was chosen as cut-off. Cath D > or = median value was closely related to neck lymph node involvement at presentation and to a short metastasis-free survival (MFS) and actual overall survival (OS). The 5-year MFS was 71% for patients with Cath D < median value tumors as compared with 0% for patients with Cath D > or = median value tumors. Lymph node status at presentation was not related to a short MFS and OS. Cox's univariate regression analysis using Cath D as a continuous variable showed that Cath D levels are correlated with neck lymph node metastasis. On multivariate analysis, Cath D status proved to be an independent factor for predicting a short MFS. Cath D assay may prove to be particularly useful in identifying laryngeal cancer patients who, with or without neck lymph node involvement at presentation, are at high risk of metastatic disease and poor outcome.