Concordance between biopsy and radical prostatectomy specimen Gleason score in internal and external pathology facilities

Background: Biopsy Gleason score (bGS) is an important tool for staging and decision making in patients with prostate cancer. Therefore, the data from biopsy should be both reproducible across different pathologists and predictive of the true underlying tumour. We evaluated the agreement between bGS with prostatectomy Gleason score (pGS) comparing patients who underwent prostate biopsy at our hospital with those who did it at an outside facility.

Materials and methods: We retrospectively analyzed patients who underwent robot-assisted radical prostatectomy at our Hospital in 2011 and 2012. Patients were divided depending on the site of prostate biopsy. We calculated a weighted κ statistic to evaluate the concordance from bGS and pGS in the two groups and to evaluate the Gleason score (GS) concordance comparing the proportion of positive cores at biopsy.

Results: A total of 124 patients with completed data were identified (70 patients performed biopsy at our institution and 54 at an outside facility). The weighted κ score for GS agreement was 0.40 for our Institution and 0.27 for other facilities. The weighted κ score stratified by biopsy hospital for patients with at least 30% of positive cores was 0.46 for our hospital and 0.42 for other facilities.

Conclusion: Internal prostate biopsy predicted better pGS than outside facility biopsy reports. When the percentage of biopsy-positive cores increases, the agreement between bGS and pGS is similar between the two groups. For certain cases in which an outside laboratory biopsy results in equivocal clinical decision, biopsy re-evaluation by internal pathologists can help reveal the true underlying tumor architecture and extension.