Category: Imaging & Image Guided Therapy: New Therapies
Introduction & Objective : PSMA-PET imaging has shown utility in locating biochemical recurrences in prostate cancer and is increasingly being applied to preoperative staging. Our goal was to evaluate PSMA-PET guidance during robotic prostatectomy and HIFU treatments as well as to evaluate intraoperative dosing of 68Ga-PSMA-11 for immediate postoperative detection of prostate cancer.
Men with prostate cancer and scheduled for robotic prostatectomy or HIFU were screened for inclusion in this prospective, single arm, phase 2 clinic trial. Enrolled patients received a 68Ga-PSMA-11 PET-CT scan for preoperative staging. Intraoperatively 68Ga-PSMA-11 was redosed and the extirpated prostate specimen was scanned with a high-resolution (3mm) small bore animal PET scanner in a subset (n=11). A subset had their specimen bivalved and evaluated with a 3mm beta-ray hand probe (n=5). A subset had HIFU treatment instead of surgery (n=3). The prostate was evaluated with whole-mount pathologic processing for intra-lesion analysis and registration with PET imaging for those undergoing prostatectomy.
A total of 15 patients enrolled and underwent treatment. The median age and PSA were 61.0years and 7.8ng/mL for the 12 patients undergoing prostatectomy. The final pathologic Gleason was: 4+5/5+4 (n=4), 4+3 (n=3), and 3+4 (n=5). The staging PSMA-PET accurately predicted seminal vesicle invasion (pT3b) in 4 of 5 patients and 5 of 5 when utilizing the immediate postoperative high-resolution scanner. The staging PSMA-PET accurately predicted 1 of 2 lymph node invasions. The detected node was 6mm and the missed node was 2mm. Positive PET lesions were seen all 12 cases. The median (IQR) SUVmax for intraprostatic cancer was 10.6 (8-13) and for benign prostate was 3.6 (3-5). The PSMA-PET images showed good registration with whole-mount pathology for primary Gleason patterns ≥4+3 (n=7). The beta hand probe did not consistently detect positive cancer margins. Two of the HIFU cases had PSMA-PET positive lesions for targeted treatment (4+3, 4+4) while one (3+4) did not.
Conclusions : PSMA-PET clinical staging accurately detected Gleason patterns ≥4+3 and predicted seminal vesical invasion. PSMA-PET could be helpful in surgical planning. Further investigation in a larger cohort is needed.
Clinton Bahler– Assistant Professor, Indiana University, Indianapolis, Indiana
Mark Green– Professor, Indiana University, Indianapolis, Indiana
Gary Hutchins– Professor, Indiana University, Indianapolis, Indiana
Liang Cheng– Professor, Indiana University, Indianapolis, Indiana
James Fletcher– Professor, Indiana University, Indianapolis, Indiana
Michael Koch– Professor and Chair, Indiana University, Indianapolis, Indiana