For this study, data on 286 consecutive patients imaged with the ExactVu micro-ultrasound system between October 2017 and September 2018 were prospectively collected. All patients were scheduled for prostate biopsy due to clinical suspicion of prostate cancer. The PRIMUS protocol was used to locate targets on micro-ultrasound. Lesions with a PRIMUS score ≥ 3 were targeted. The PRIMUS protocol is as follows:
Patients were also subjected to systematic prostatic biopsies. The presence of overall prostate cancer and of clinically significant prostate cancer (defined as a Gleason score ≥7 cancer) was determined and the diagnostic performance of micro-ultrasound was assessed. Finally, logistic regression models were fitted to test the predictors of clinically significant prostate cancer.
The mean patient age was 64.7 (+/-7.6) years, the mean total PSA was 9.01 (+/- 14.37) ng/mL and mean prostate volume was 57.3 (+/- 31.3) mL. Overall, 130 (45.5%) patients were in the repeat biopsy setting. Micro-ultrasound detected prostate lesions with a PRIMUS score of 3 in 36 (12.6%) of patients, a score of 4 in 133 (46.5%), and 5 in 66 (23.1%) patients, while in 51 (17.8%) individuals micro-ultrasound did not identify any target. Overall prostate cancer and clinically significant prostate cancer detection rates were 53.5% (n=133) and 36.0% (n=103). Micro-ultrasound provided high sensitivity, with 89.3% of patients (92/103) with clinically significant prostate cancer having at least one PRIMUS score ≥ 3 lesions. Similarly, negative predictive value was 82.3%, with 42 out of 51 patients with no micro-ultrasound targets receiving a benign diagnosis after systematic biopsy. Positive predictive value and specificity were significantly lower (40.0% and 22.9%), likely due to over-targeting. In univariable modeling, patients with a PRIMUS 4 or 5 lesion showed a 3.3- and a 9.3-fold higher risk of harboring clinically significant prostate cancer compared to those with a micro-ultrasound PRIMUS ≤ 3 pattern (p≤0.001). These results were confirmed also in multivariable models where, after adjustment for several confounders, patients with a PRIMUS 4 or 5 lesion had a 2.9- and 4.7-fold higher risk of harboring clinically significant prostate cancer (p≤0.018), respectively.
PRIMUS 4 and 5 lesions appear as follows:
The conclusion of this abstract is that micro-ultrasound is a promising new imaging modality showing high sensitivity to detect clinically significant prostate cancer. In addition, the system appears to be capable of reliably excluding the presence of clinically significant prostate cancer in the great majority of patients. The micro-ultrasound platform provides a practical solution as a new tool for urologists to perform targeted biopsies within a usual urological workflow. However, multi-institutional efforts are still needed to further support the adoption of this tool in the diagnostic pathway of patients with suspected PCa.
Presented by: Giovanni Lughezzani, MD, Humanitas Clinical and Research Hospital, Milan, Italy
Written By: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University - Medical College of Georgia, Twitter: @zklaassen_md at the 34th European Association of Urology (EAU 2019) #EAU19, conference in Barcelona, Spain from March 15-19, 2019.