INTRODUCTION AND OBJECTIVE:
Despite limitations in diagnostic accuracy, transrectal ultrasound guided-systematic biopsy remains the most common method of prostate cancer (PCa) staging. Many low-risk PCa patients are deemed eligible for active surveillance based on systematic biopsy alone. The objective of this study was to analyze characteristics of patients eligible for AS based on systematic biopsy, who later underwent radical prostatectomy and were found to have Gleason Grade (GG) ≥3 disease.
Patients were enrolled in a nationally registered clinical trial to evaluate the use of MRI-targeted combined biopsy (NCT00102544). We queried our institutional database for patients who underwent radical prostatectomy between June 2007 and July 2020. Patients with GG1 or GG2 on systematic biopsy were included. Upgrading was determined by comparing GG on systematic and targeted biopsies, to GG on wholemount prostate specimen. Logistic regression models adjusted for age, BMI, and total prostate volume were used to identify predictors of upgrading to GG ≥3 disease. Chi-squared tests were used to compare categorical variables.
A total of 773 patients who underwent radical prostatectomy between June 2007 and July 2020 were identified in our institutional database. Among patients who underwent combined biopsy (n = 495), 280 were diagnosed with GG1 (n=03) or GG2 (n=177) on systematic biopsy. The rate of upgrading to GG ≥ 3 was significantly higher for systematic than targeted biopsy (20.0% vs 5.0%, p<0.0001). Increased age at time of surgery was associated with increased odds of upgrading to GG≥ 3 (OR: 1.13, 95% CI: 1.03–1.25, p=.014). Targeted biopsy GG was associated with increased odds of upgrading to GG ≥3 on wholemount pathology (OR: 2.91, 95% CI: 1.74-5.38, p<0.001). Total number of lesions found on MRI was associated with lower odds of upgrading (OR: 0.41, 95% CI: 0.21-0.70, p=0.003). PSA at time of surgery, BMI, highest PIRADS score on MRI, and total prostate volume on MRI were not associated with upgrading to GG ≥ 3 on wholemount pathology (p>0.05).
Approximately 1 in 5 patients eligible for AS based on 12-core TRUS-systematic biopsy portion of combined biopsy have GG ≥3 on wholemount histopathology after radical prostatectomy. Older age, GG on MRI-targeted biopsy, and fewer total lesions on pre-biopsy MRI are associated with upgrading to GG ≥3 on wholemount histopathology. Our findings support the use of MRI-targeted biopsy for risk-stratifying patients on AS.
Source of Funding:
NIH Intramural Funding, NIH Medical Research Scholars Program, Foundation for the NIH