Detection of the 67-kD laminin receptor in prostate cancer biopsies as a predictor of recurrence after radical prostatectomy

INTRODUCTION & OBJECTIVES: The identification of reliable prognostic indicators for prostate cancer (PC) is a major challenge of today cancer research. The 67-KD laminin receptor (67LR) is a cell surface associated molecule whose increased expression is associated with the aggressiveness of a variety of human cancers. We recently showed that 67LR detection in PC tissues from radical prostatectomy (RP) specimens was an independent predictor of biochemical relapse in patients with clinically localized PC (JNCI, 89:1224-1227, 1997). In this study, we assessed 67LR detection in diagnostic biopsies as a predictor of biochemical relapse after RP.
MATERIAL & METHODS: A total of 151 patients with clinically confined PC underwent RP. PC tissue sections from both biopsy and RP specimens were immunohistochemically analyzed for 67LR expression. The importance of 67LR expression was evaluated according to the intensity and extent of the staining. Preoperative and postoperative clinicopathological parameters, including 67LR expression, were correlated with each other and tested as predictors of biochemical relapse.
RESULTS: 67LR was detected in 67.5% and 68.2% of biopsies and RPs, respectively. 67LR detection in RP specimens was an independent predictor of relapse. The level of 67LR expression in the biopsy was significantly associated with the biopsy Gleason score (p<0.05) but failed to predict the pathological stage (p>0.1). Biochemical progression-free estimates for patients whose biopsy did or did not express the protein differed with only borderline statistical significance (p=0.05). Multivariate analysis identified biopsy Gleason score as the only independent preoperative predictor of recurrence. Significant discrepancies in levels of 67LR expression were found between matched biopsy and RP specimens, with exact agreement rates <40% (p<0.05).
CONCLUSIONS: 67LR detection in PC biopsies was not a significant preoperative predictor of outcome after RP. Heterogeneity of 67LR expression and biopsy sampling errors most likely represented the main raisons for discordant prognostic results depending on whether 67LR expression was evaluated either in biopsies or in RPs.