The role of cathepsin D and PAI-1 in primary invasive breast cancer as prognosticators and predictors of treatment benefit with adjuvant tamoxifen.

In the last few years there has been an increased interest in treatment predictive factors in breast cancer patients. The aim of the study was to analyse the role of cathepsin D and plasminogen activator inhibitor-1 (PAI-1) expression as independent prognosticators and to assess their predictive value with respect to tamoxifen treatment. This study comprises 1851 patients with primary breast cancer diagnosed during 1988-1992. Their median age was 62 years (range: 24-91). The end-point was distant disease recurrence-free interval. Adjuvant treatment with tamoxifen was given to 1136 patients (61%). The median follow-up time was 59 months (range: 39-88). Cathepsin D content was shown to be a significant independent prognosticator in multivariate Cox analysis (P=0.02). The optimal cut-off level was 10 fmol/mg protein, other cut-off levels did not improve the results. The level of cathepsin D also appeared to predict the benefit of tamoxifen among oestrogen receptor (ER)-positive patients although this result did not reach statistical significance (P=0.09). In a multivariate Cox analysis including 497 patients PAI-1 content was shown to be a significant independent prognosticator (P=0.003) but did not appear to predict the benefit of tamoxifen treatment. The optimal cut-off level appeared to be 3 ng/mg protein, which was close to the median value 2.5 ng/mg (range: 0-51). We conclude that cathepsin D is a significant independent prognosticator and may possibly also predict the benefit of tamoxifen amongst ER-positive patients. PAI-1 was also found to be a strong independent prognosticator but no treatment interaction with adjuvant tamoxifen was found.