The Gleason score obtained on prostatic biopsies is an essential element in the treatment decision for localized prostate cancer. The objective of this study was to evaluate the correlation between the biopsy Gleason score and the definitive Gleason score and to propose a classification into 3 groups in order to improve this correlation.
Material and methods: One hundred radical prostatectomies were performed between 1995 and 1998. Eighty four of these patients underwent 6 biopsies. The Gleason score of the biopsies and operative specimens were compared. The concordance between the biopsy Gleason score and the operative specimen Gleason score was initially analysed score by score. The concordance was then established according to three groups, well differentiated tumours (score 2-4), moderately differentiated tumours (score 5-7), poorly differentiated tumours (score 8-10).
Results: The concordance between the biopsy Gleason score and the operative specimen Gleason score was perfect in only 37% of cases. A 1-point difference of the score was observed in 35.7% of cases and a 2-point or greater difference was observed in 27.3% of cases. By classifying patients into 3 groups, the concordance increased from 37% to 72.6%.
Conclusion: The classification of patients into three distinct groups (well, moderately and poorly differentiated tumours) increases the concordance between the biopsy Gleason score and the definitive Gleason score. However, the limitations of the biopsy Gleason score must be kept in mind, particularly in the case of low-grade tumours.