Upgrading of Standard and Transperineal Transrectal Ultrasound Guided Prostate Biopsies on Subsequent Radical Prostatectomy: A Population Based Study

摘要

Gleason grade on prostate biopsy is a major component on which treatment decisions for prostate cancer are based. However a significant percentage, approximately 30% of patients with Gleason 6 disease who subsequently undergo radical prostatectomy are upgraded to Gleason 7 or higher.[1]Correct grading of prostate cancer in the Gleason 6 population when compared to radical prostatectomy histology occurs in approximately 50-60% of cases.[3]Grading inaccuracy on prostate biopsy is therefore of significant concern in patients who receive radiotherapy or active surveillance, as the true grade of their prostate cancer may never be determined and had they been upgraded they may not have opted for non-extirpative treatment.This study therefore, utilises the population based SA-PCCOC (South Australian Prostate Cancer Outcome Collaborative) database to assess upgrading in Gleason 7 prostate cancer, as this group of patients are candidates for both surgical, radiotherapy and surveillance treatment options. (AUA guidelines for management of localised prostate cancer 2007, updated 2009)A further analysis is performed to assess the upgrading rate for transperineal prostate biopsy (TP) as this technique has been suggested to be a means to improve grading accuracy in prostate cancer .[4] BACKGROUND Gleason grade on prostate biopsy is a major component on which treatment decisions for prostate cancer are based. However a significant percentage, approximately 30% of patients with Gleason 6 disease who subsequently undergo radical prostatectomy are upgraded to Gleason 7 or higher.[1]Correct grading of prostate cancer in the Gleason 6 population when compared to radical prostatectomy histology occurs in approximately 50-60% of cases.[3]Grading inaccuracy on prostate biopsy is therefore of significant concern in patients who receive radiotherapy or active surveillance, as the true grade of their prostate cancer may never be determined and had they been upgraded they may not have opted for non-extirpative treatment.This study therefore, utilises the population based SA-PCCOC (South Australian Prostate Cancer Outcome Collaborative) database to assess upgrading in Gleason 7 prostate cancer, as this group of patients are candidates for both surgical, radiotherapy and surveillance treatment options. (AUA guidelines for management of localised prostate cancer 2007, updated 2009)A further analysis is performed to assess the upgrading rate for transperineal prostate biopsy (TP) as this technique has been suggested to be a means to improve grading accuracy in prostate cancer .[4] METHODS The SA-PCCOC database was initiated in 1996 and is the largest population based, prospective prostate cancer database in the Southern Hemisphere. It contains more than 7500 patients and captures approximately 50% of all new prostate cancer diagnosis in South Australia, from both the private and public sectors. Current accrual is approximately 1000 new patients every year.An initial audit was performed in 2011 to assess the rate of upgrading in patients with Gleason 7 prostate cancer on standard TRUS biopsy (either 3+4 or 4+3), who subsequently had a radical prostatectomy.A subsequent audit was performed in 2012 to assess the rate of upgrading in patients who underwent a TP biopsy (any Gleason grade) and subsequently had a radical prostatectomy.Explanatory variables assessed for the two populations included: patient demographics, PSA, TRUS biopsy grade, total cores, total positive cores, histology and duration to radical prostatectomy.A separate analysis was performed in the standard TRUS biopsy population to assess upgrading in ‘low volume’ Gleason 4 disease.This was defined as patients who had only 1 core positive for Gleason 4 disease, or 2 cores positive for Gleason 4 disease if more than 10 cores were taken.The primary outcome variable for both populations was upgrading which was defined as:- Increase in Gleason grade from 3+4 to 4+3 or higher- Any increase in total Gl