Presurgical 68Ga-PSMA-11 Positron Emission Tomography for Biochemical Recurrence Risk Assessment: A Follow-up Analysis of a Multicenter Prospective Phase 3 Imaging Trial.

BACKGROUND: In the initial staging of patients with high-risk prostate cancer (PCa), prostate-specific membrane antigen positron emission tomography (PSMA-PET) has been established as a front-line imaging modality. The increasing number of PSMA-PET scans performed in the primary staging setting might be associated with decreases in biochemical recurrence (BCR)-free survival (BCR-FS). OBJECTIVE: To assess the added prognostic value of presurgical PSMA-PET for BCR-FS compared with the presurgical Cancer of the Prostate Risk Assessment (CAPRA) and postsurgical CAPRA-Surgery (CAPRA-S) scores in patients with intermediate- to high-risk PCa treated with radical prostatectomy (RP) and pelvic lymph node dissection. DESIGN, SETTING, AND PARTICIPANTS: This is a follow-up study of the surgical cohort evaluated in the multicenter prospective phase 3 imaging trial (n = 277; NCT03368547, NCT02611882, and NCT02919111). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Each 68Ga-PSMA-11-PET scan was read by three blinded independent readers. PSMA-PET prostate uptake (low vs high), PSMA-PET extraprostatic disease (N1/M1), and CAPRA and CAPRA-S scores were used to assess the risk of BCR. Patients were followed after RP by local investigators using electronic medical records. BCR was defined by a prostate-specific antigen (PSA) level increasing to ≥0.2 ng/ml after RP or initiation of PCa-specific secondary treatment (>6 mo after surgery). Univariate and multivariable Cox models, and c-statistic index were performed to assess the prognostic value of PSMA-PET and for a comparison with the CAPRA and CAPRA-S scores. RESULTS AND LIMITATIONS: From December 2015 to December 2019, 277 patients underwent surgery after PSMA-PET. Clinical follow-up was obtained in 240/277 (87%) patients. The median follow-up after surgery was 32.4 (interquartile range 23.3-42.9) mo. Of 240 BCR events, 91 (38%) were observed. PSMA-PET N1/M1 was found in 41/240 (17%) patients. PSMA-PET prostate uptake, PSMA-PET N1/M1, and CAPRA and CAPRA-S scores were significant univariate predictors of BCR. The addition of PSMA-PET N1/M1 status to the presurgical CAPRA score improved the risk assessment for BCR significantly in comparison with the presurgical CAPRA score alone (c-statistic 0.70 [0.64-0.75] vs 0.63 [0.57-0.69]; p < 0.001). The C-index of the postsurgical model utilizing the postsurgical CAPRA-S score alone was not significantly different from the presurgical model combining the presurgical CAPRA score and PSMA-PET N1/M1 status (p = 0.19). CONCLUSIONS: Presurgical PSMA-PET was a strong prognostic biomarker improving BCR-FS risk assessment. Its implementation in the presurgical risk assessment with the CAPRA score improved the performance and reduced the difference with the reference standard (postsurgical CAPRA-S score). PATIENT SUMMARY: The use prostate-specific membrane antigen positron emission tomography improved the assessment of biochemical recurrence risk in patients with intermediate- and high-risk prostate cancer who were treated with radical prostatectomy and pelvic lymph node dissection.

Underutilization of Androgen Deprivation Therapy with External Beam Radiotherapy in Men with High-grade Prostate Cancer.

Multiple randomized trials have shown a survival benefit to long durations of androgen deprivation therapy (ADT) in patients with Gleason grade group (GG) 4-5 (ie, Gleason score 8-10) prostate cancer (PCa) undergoing definitive external beam radiotherapy (EBRT). We conducted a population-based retrospective study utilizing the complete Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database from 2008 to 2011, extracting PCa patients of non-Hispanic white (NHW) and African-American (AA) race diagnosed with GG 4-5PCa who received EBRT with or without concomitant ADT. Of 961 patients receiving definitive EBRT, 225 (23.4%) received no ADT, 297 (30.9%) received 1-6mo of ADT, 313 (32.6) received 7-23mo of ADT, and 126 (13.1%) received ≥24mo of ADT. On multinomial logistic regression after inverse probability treatment weighting to balance for differences in other covariates, AA men still had significantly lower odds of receiving 1-6mo of ADT versus no ADT compared with NHW men (odds ratios 0.519 [95% confidence interval, 0.384-0.700]). In conclusion, long-duration ADT is underutilized, with nearly 90% of patients with GG 4-5PCa receiving <24mo of concomitant ADT, and AA men are less likely to receive ADT than NHW men. PATIENT SUMMARY: In this report, we examined the utilization of concomitant androgen deprivation therapy (ADT) among men with high-grade prostate cancer undergoing definitive external beam radiotherapy. We found that long-duration ADT was underutilized overall; moreover, African-American men were less likely to receive concomitant ADT than non-Hispanic white men.

Cost-Effectiveness of Metastasis-Directed Therapy in Oligorecurrent Hormone-Sensitive Prostate Cancer.

PURPOSE: Oligorecurrent prostate cancer has historically been treated with indefinite androgen deprivation therapy (ADT), although many patients and providers opt to defer this treatment at the time of recurrence given quality-of-life and/or comorbidity considerations. Recently, metastasis-directed therapy (MDT) has emerged as a potential intermediary between surveillance and immediate continuous ADT. Simultaneously, advanced systemic therapy in addition to ADT has also been shown to improve survival in metastatic hormone-sensitive disease. This study aimed to compare the cost-effectiveness of treating oligorecurrent patients with upfront MDT before standard-of-care systemic therapy. METHODS AND MATERIALS: A Markov-based cost-effectiveness analysis was constructed comparing 3 strategies: (1) upfront MDT → salvage abiraterone acetate plus prednisone (AAP) + ADT → salvage docetaxel + ADT; (2) upfront AAP + ADT → salvage docetaxel + ADT; and (3) upfront docetaxel + ADT → salvage AAP + ADT. Transition probabilities and utilities were derived from the literature. Using a 10-year time horizon and willingness-to-pay threshold of $100,000/quality-adjusted life year (QALY), net monetary benefit values were subsequently calculated for each treatment strategy. RESULTS: At 10 years, the base case revealed a total cost of $141,148, $166,807, and $136,154 with QALYs of 4.63, 4.89, and 4.00, respectively, reflecting a net monetary benefit of $322,240, $322,018, and $263,407 for upfront MDT, upfront AAP + ADT, and upfront docetaxel + ADT, respectively. In the probabilistic sensitivity analysis using a Monte Carlo simulation (1,000,000 simulations), upfront MDT was the cost-effective strategy in 53.6% of simulations. The probabilistic sensitivity analysis revealed 95% confidence intervals for cost ($75,914-$179,862, $124,431-$223,892, and $103,298-$180,617) and utility in QALYs (3.85-6.12, 3.91-5.86, and 3.02-5.22) for upfront MDT, upfront AAP + ADT, and upfront docetaxel + ADT, respectively. CONCLUSIONS: At 10 years, upfront MDT followed by salvage AAP + ADT, is comparably cost-effective compared with upfront standard-of-care systemic therapy and may be considered a viable treatment strategy, especially in patients wishing to defer systemic therapy for quality-of-life or comorbidity concerns. Additional studies are needed to determine whether MDT causes a sustained meaningful delay in disease natural history and whether any benefit exists in combining MDT with upfront advanced systemic therapy.

Assessment of 68Ga-PSMA-11 PET Accuracy in Localizing Recurrent Prostate Cancer: A Prospective Single-Arm Clinical Trial.

IMPORTANCE: In retrospective studies, 68Ga-PSMA-11 positron emission tomographic (PET) imaging improves detection of biochemically recurrent prostate cancer compared with conventional imaging. OBJECTIVE: To assess 68Ga-PSMA-11 PET accuracy in a prospective multicenter trial. DESIGN, SETTING, AND PARTICIPANTS: In this single-arm prospective trial conducted at University of California, San Francisco and University of California, Los Angeles, 635 patients with biochemically recurrent prostate cancer after prostatectomy (n = 262, 41%), radiation therapy (n = 169, 27%), or both (n = 204, 32%) underwent 68Ga-PSMA-11 PET. Presence of prostate cancer was recorded by 3 blinded readers on a per-patient and per-region base. Lesions were validated by histopathologic analysis and a composite reference standard. MAIN OUTCOMES AND MEASURES: Endpoints were positive predictive value (PPV), detection rate, interreader reproducibility, and safety. RESULTS: A total of 635 men were enrolled with a median age of 69 years (range, 44-95 years). On a per-patient basis, PPV was 0.84 (95% CI, 0.75-0.90) by histopathologic validation (primary endpoint, n = 87) and 0.92 (95% CI, 0.88-0.95) by the composite reference standard (n = 217). 68Ga-PSMA-11 PET localized recurrent prostate cancer in 475 of 635 (75%) patients; detection rates significantly increased with prostate-specific antigen (PSA): 38% for <0.5 ng/mL (n = 136), 57% for 0.5 to <1.0 ng/mL (n = 79), 84% for 1.0 to <2.0 ng/mL (n = 89), 86% for 2.0 to <5.0 ng/mL (n = 158), and 97% for ≥5.0 ng/mL (n = 173, P < .001). Interreader reproducibility was substantial (Fleiss κ, 0.65-0.78). There were no serious adverse events associated with 68Ga-PSMA-11 administration. PET-directed focal therapy alone led to a PSA drop of 50% or more in 31 of 39 (80%) patients. CONCLUSIONS AND RELEVANCE: Using blinded reads and independent lesion validation, we establish high PPV for 68Ga-PSMA-11 PET, detection rate and interreader agreement for localization of recurrent prostate cancer. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT02940262 and NCT03353740.

Multiregional Radiogenomic Assessment of Prostate Microenvironments with Multiparametric MR Imaging and DNA Whole-Exome Sequencing of Prostate Glands with Adenocarcinoma.

Purpose To assess the underlying genomic variation of prostate gland microenvironments of patients with prostate adenocarcinoma in the context of colocalized multiparametric magnetic resonance (MR) imaging and histopathologic assessment of normal and abnormal regions by using whole-exome sequencing. Materials and Methods Six patients with prostate adenocarcinoma who underwent robotic prostatectomy with whole-mount preservation of the prostate were identified, which enabled spatial mapping between preoperative multiparametric MR imaging and the gland. Four regions of interest were identified within each gland, including regions found to be normal and abnormal via histopathologic analysis. Whole-exome DNA sequencing (>50 times coverage) was performed on each of these spatially targeted regions. Radiogenomic analysis of imaging and mutation data were performed with hierarchical clustering, phylogenetic analysis, and principal component analysis. Results Radiogenomic multiparametric MR imaging and whole-exome spatial characterization in six patients with prostate adenocarcinoma (three patients, Gleason score of 3 + 4; and three patients, Gleason score of 4 + 5) was performed across 23 spatially distinct regions. Hierarchical clustering separated histopathologic analysis-proven high-grade lesions from the normal regions, and this reflected concordance between multiparametric MR imaging and resultant histopathologic analysis in all patients. Seventy-seven mutations involving 29 cancer-associated genes across the 23 spatially distinct prostate samples were identified. There was no significant difference in mutation load in cancer-associated genes between regions that were proven to be normal via histopathologic analysis (34 mutations per sample ± 19), mildly suspicious via multiparametric MR imaging (37 mutations per sample ± 21), intermediately suspicious via multiparametric MR imaging (31 mutations per sample ± 15), and high-grade cancer (33 mutations per sample ± 18) (P = .30). Principal component analysis resolved samples from different patients and further classified samples (regardless of histopathologic status) from prostate glands with Gleason score 3 + 4 versus 4 + 5 samples. Conclusion Multiregion spatial multiparametric MR imaging and whole-exome radiogenomic analysis of prostate glands with adenocarcinoma shows a continuum of mutations across regions that were found via histologic analysis to be high grade and normal. © RSNA, 2017 Online supplemental material is available for this article.