- This study investigated concordance between Gleason grade group on biopsy versus radical prostatectomy specimens while comparing both transperineal and transrectal approaches, and both standard template biopsy (SBx) and targeted biopsy (TBx)
- Data were analyzed retrospectively on 205 patients who underwent TBx and 12-core SBx through the transrectal approach, and 105 who underwent TBx and 20-core SBx through the transperineal approach
- The combination of SBx and TBx led to a better pathological concordance rate and lower upgrading rate for both approaches
- Transperineal biopsy was associated with a lower risk of upgrading from Gleason grade group 1 on biopsy to clinically significant prostate cancer on radical prostatectomy
- For patients who have at least one prostate lesion visible on MRI, the combination of TBx and 20-core SBx through the transperineal approach is advised
Recent studies support combining targeted prostate biopsy (TBx) and 12-core standard template biopsy (SBx) for patients who have suspicious lesions identified on multiparametric MRI. Transperineal biopsy is becoming the favored approach because it allows more comprehensive sampling of the prostate with lower risk of complications compared with the transrectal approach.
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Researchers at Massachusetts General Hospital are the first to investigate concordance between Gleason grade (GG) group on biopsy versus radical prostatectomy (RP) specimens while comparing both transperineal and transrectal approaches and both SBx and TBx. Their findings affirm the value of combining SBx and TBx, and using the transperineal approach.
Shulin Wu, MD, PhD, manager of the Urology and Pathology Research Laboratory, Adam S. Feldman, MD, MPH, director of research and a urologic oncologist in the Department of Urology, Douglas M. Dahl, MD, director of urologic oncology in the Department, Chin-Lee Wu, MD, PhD, pathologist and director of Genitourinary Pathology Services at Mass General and the Mass General Cancer Center, and colleagues report in Urology.
The researchers retrospectively analyzed data on 310 patients who underwent combined SBx and TBx, followed by RP between September 2019 and February 2021. All patients had one or more lesions identified on prior prostate multiparametric MRI.
205 patients underwent TBx and 12-core SBx through the transrectal approach. The other 105 underwent TBx and 20-core SBx through the transperineal approach.
Pathology on SBx, TBx, and combined biopsy (CBx) from both approaches were compared with the pathologic findings on RP:
- The results were considered concordant if the GG matched
- The case was considered upgraded if higher GG was identified on RP than biopsy
- The case was considered downgraded if lower GG was identified on RP than biopsy
Clinically significant prostate cancer was defined as GG ≥2.
Transperineal vs. Transrectal Approaches
Transperineal CBx performed somewhat better than transrectal CBx, although the results were not significantly different:
- Concordance—64% vs. 57%
- Upgrading—22% vs. 23%
- Downgrading—14% vs. 20%
The agreement between GG from biopsy and RP was highest for transperineal CBx (κ=0.48), followed by transrectal CBx (κ=0.39), transperineal TBx (κ=0.36), transrectal TBx (κ=0.35), transperineal SBx (κ=0.34), and transrectal SBx (κ=0.26).
TBx vs. SBx
When SBx and TBx were compared without being divided into transrectal or transperineal, TBx was significantly more highly concordant (52% vs. 45%, P=0.0123). When compared according to approach, the only significant difference was that transrectal TBx showed higher concordance than transrectal SBx (52% vs. 42%; P=0.002).
Frequency of Upgrading
Upgrading from biopsy is a greater clinical concern than downgrading, since patients inaccurately assigned GG1 would be undertreated.
Of the 69 cases that CBx diagnosed as GG1, 38 (55%) were upgraded at the time of RP to clinically significant cancer. The frequency of upgrading was similar for the transrectal and transperineal approaches.
Recommendations for the Clinic
Conventional 12-core prostate SBx seems insufficient to use for risk classification. For patients who have at least one prostate lesion visible on MRI, the combination of TBx and 20-core SBx through the transperineal approach is advised.
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