Prostate biopsy concordance in a large population-based sample: a Surveillance, Epidemiology and End Results study

To use the Surveillance, Epidemiology and End Results database in order to evaluate prostate biopsy concordance in a large population-based sample.

We identified 34 195 men who were diagnosed with prostate cancer and underwent a radical prostatectomy from 2010 to 2011. All patients also had to have both clinical and pathological Gleason scores available for analysis. The concordance of the biopsy Gleason score to the pathological Gleason score was analysed using the coefficient of agreement (κ). Univariate and multivariate logistic regression analyses were performed to determine potential factors that may impact concordance of Gleason score.

Overall, the clinical and pathological Gleason scores matched in 55.4% of patients. The concordance rates were 55.3% for Gleason 6, 66.9% for Gleason 3+4, 42.9% for Gleason 4+3 and 24.8% for Gleason 8, with frequent downgrading to Gleason 7. The κ for Gleason score concordance was 0.36 (95% CI 0.35 to 0.37), indicating fair agreement. The weighted κ for Gleason score concordance was 0.51 (95% CI 0.50 to 0.52), indicating moderate agreement. Additionally, the Bowker tests of symmetry were highly significant (p<0.001), indicating that when discordant findings were present, pathological upgrading was more common than downgrading.

This study is, to our knowledge, the largest contemporary study of prostate biopsy concordance. We found that there continues to be significant Gleason migration both upward from biopsy Gleason 6 or 3+4 and downgrading from biopsy Gleason ≥8. Further studies are needed to better determine other potential genomic or biologic factors that may help increase the biopsy Gleason concordance.