A prospective, multicenter head-to-head comparative study in patients with primary high-risk prostate cancer investigating the bone lesion detection of conventional imaging and 18F-PSMA-PET/CT

PURPOSE

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) is an emerging staging tool for patients with primary high-risk prostate cancer (PCa). Patients with primary metastatic disease are staged using PSMA-PET/CT imaging, while previously published randomized clinical trials relied on conventional imaging (i.e., bone scintigraphy (BS) results. The aim of this study was to compare the ability of bone metastatic lesion detection and changes in staging for ¹⁸F-PSMA-PET/CT versus BS in high-risk PCa patients.

METHODS

79 patients with high-risk PCa were prospectively staged using BS and subsequent ¹⁸F-PSMA-PET/CT before initial therapy. Patients who presented with a BS showing no metastases represented Group 1, and patients with a BS showing low-volume disease according to the CHAARTED criteria (<4 bone metastases, no metastases outside vertebral column or pelvis and no visceral metastases) represented Group 2. Metastatic risk group according to CHAARTED and treatment strategies based on both imaging modalities were assessed.

RESULTS

A change of CHAARTED risk group was observed in 9/70 (12.8%) of patients in Group 1. In Group 2, a change of risk group was found in 66.7% of patients, due to either upstaging (4/9 patients (44.4%)) and downstaging (2/9 patients (22.2%)). Treatment changes due to use of a different imaging modality occurred in almost 20% of patients.

CONCLUSION

In patients with negative for cancer results on BS, upstaging on ¹⁸F-PSMA-PET/CT occurred only infrequently. Moreover, ¹⁸F-PSMA-PET/CT resulted in both upstaging and downstaging in a substantial subset of patients with low-volume metastatic disease on BS. Treatment changes occurred in almost 20% of cases depending on imaging results.

Pelvic lymph-node staging with 18F-DCFPyL PET/CT prior to extended pelvic lymph-node dissection in primary prostate cancer - the SALT trial

PURPOSE

The detection of lymph-node metastases (N1) with conventional imaging such as magnetic resonance imaging (MRI) and computed tomography (CT) is inadequate for primarily diagnosed prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) PET/CT is successfully introduced for the staging of (biochemically) recurrent PCa. Besides the frequently used 68gallium-labelled PSMA tracers, 18fluorine-labelled PSMA tracers are available. This study examined the diagnostic accuracy of 18F-DCFPyL (PSMA) PET/CT for lymph-node staging in primary PCa.

METHODS

This was a prospective, multicentre cohort study. Patients with primary PCa underwent 18F-DCFPyL PET/CT prior to robot-assisted radical prostatectomy (RARP) with extended pelvic lymph-node dissection (ePLND). Patients were included between October 2017 and January 2020. A Memorial Sloan Kettering Cancer Centre (MSKCC) nomogram risk probability of ≥ 8% of lymph-node metastases was set to perform ePLND. All images were reviewed by two experienced nuclear physicians, and were compared with post-operative histopathologic results.

RESULTS

A total of 117 patients was analysed. Lymph-node metastases (N1) were histologically diagnosed in 17/117 patients (14.5%). The sensitivity, specificity, positive predictive value and negative predictive value for the 18F-DCFPyL PET/CT detection of pelvic lymph-node metastases on a patient level were 41.2% (confidence interval (CI): 19.4-66.5%), 94.0% (CI 86.9-97.5%), 53.8% (CI 26.1-79.6%) and 90.4% (CI 82.6-95.0%), respectively.

CONCLUSION

18F-DCFPyL PET/CT showed a high specificity (94.4%), yet a limited sensitivity (41.2%) for the detection of pelvic lymph-node metastases in primary PCa. This implies that current PSMA PET/CT imaging cannot replace diagnostic ePLND. Further research is necessary to define the exact place of PSMA PET/CT imaging in the primary staging of PCa.

Detection of prostate cancer with 18F-DCFPyL PET/CT compared to final histopathology of radical prostatectomy specimens: is PSMA-targeted biopsy feasible? The DeTeCT trial

PURPOSE

In primary prostate cancer (PCa) patients, accurate staging and histologic grading are crucial to guide treatment decisions. ¹⁸F-DCFPyL (PSMA)-PET/CT has been successfully introduced for (re)staging PCa, showing high accuracy to localise PCa in lymph nodes and/or osseous structures. The diagnostic performance of ¹⁸F-DCFPyL-PET/CT in localizing primary PCa within the prostate gland was assessed, allowing for PSMA-guided targeted-prostate biopsy.

METHODS

Thirty patients with intermediate-/high-risk primary PCa were prospectively enrolled between May 2018 and May 2019 and underwent ¹⁸F-DCFPyL-PET/CT prior to robot-assisted radical prostatectomy (RARP). Two experienced and blinded nuclear medicine physicians assessed tumour localisation within the prostate gland on PET/CT, using a 12-segment mapping model of the prostate. The same model was used by a uro-pathologist for the RARP specimens. Based on PET/CT imaging, a potential biopsy recommendation was given per patient, based on the size and PET-intensity of the suspected PCa localisations. The biopsy recommendation was correlated to final histopathology in the RARP specimen. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for clinically significant PCa (csPCa, Gleason score ≥ 3 + 4 = 7) were assessed.

RESULTS

The segments recommended for potential targeted biopsy harboured csPCA in 28/30 patients (93%), and covered the highest Gleason score PCa segment in 26/30 patient (87%). Overall, 122 of 420 segments (29.0%) contained csPCa at final histopathological examination. Sensitivity, specificity, PPV and NPV for csPCa per segment using ¹⁸F-DCFPyL-PET/CT were 61.4%, 88.3%, 68.1% and 84.8%, respectively.

CONCLUSIONS

When comparing the PCa-localisation on ¹⁸F-DCFPyL-PET/CT with the RARP specimens, an accurate per-patient detection (93%) and localisation of csPCa was found. Thus, ¹⁸F-DCFPyL-PET/CT potentially allows for accurate PSMA-targeted biopsy.

Time-Driven activity-based costing identifies opportunities for process efficiency and cost optimization for robot-assisted laparoscopic pyeloplasty

BACKGROUND

Robot-assisted laparoscopic pyeloplasty (RALP) is a commonly performed procedure in children, but its actual cost implications on the healthcare ecosystem have not been adequately defined. Time-driven activity-based costing (TDABC) is a novel cost accounting method derived from value based healthcare systems that may offer one pathway to assess institutional costs.

OBJECTIVE

To determine the true cost of a robot-assisted laparoscopic pyeloplasty (RALP) in the pediatric population using TDABC, and compare it to traditional cost accounting. And to utilize TDABC to minimize cost and improve time-flow efficiency.

SUBJECTS/PATIENTS AND METHODS

The RALP care pathway was defined from patient arrival to the pre-operative suite to discharge from the post-anesthesia care unit (PACU). Process maps were created with an interdisciplinary team to survey RALP activities. Retrospective time stamps were obtained from the electronic medical record for fiscal year 2016 (FY16) RALP cases, and were validated by prospectively stopwatch timing additional RALP cases. Male and female pediatric patients undergoing a unilateral RALP during FY16 and during the prospective study period (June 2017-October 2017) were included. Procedure costs were calculated using TDABC after determining the capacity cost rate for all personnel and assets, and multiplying them with the time stamps.

RESULTS

25 RALP cases were analyzed for FY16. TDABC determined a total cost of $15 319/case, when direct, indirect and capital robot cost are included. Traditional cost accounting amounted to a total of $16 158/case. The current robot utilization rate is 22% of total capacity, effectively increasing the total RALP cost by 16%. Time stamps with the most variance were pre-operative services (115 ± 27.5 min), robotic console (142 min ±30.7 min) and PACU times (145 ± 101.1 min) (Figure) DISCUSSION: This study represents the first TDABC implementation in robot-assisted pediatric procedures. Previous TDABC in other areas of urology similarly revealed discrepancies between traditional cost accounting and TDABC. The present study demonstrates a higher total cost than previous cost accounting studies for the RALP, however, this is the first effort to include indirect costs in the final calculations. This study does convey the limitations of a retrospective analysis and those inherent to a single institution study.

CONCLUSION

TDABC defined the magnitude of cost variation based on robot utilization of a RALP. Traditional cost accounting overestimates the actual costs of a RALP. TDABC also identified high-cost and high variability loci in the RALP process map that will be targeted for process and quality improvement while further reducing assessed costs.