68Ga-PSMA PET/CT for restaging prostate cancer after definitive therapy: Results of a prospective single-center trial

5064 Background: Several lesion-targeted therapies exist for locally recurrent or limited stage metastatic prostate cancer (PCa) post-radiotherapy (RT) and radical prostatectomy (RP). However, detection of disease sites is limited using conventional imaging (CI) including computed tomography (CT) and bone scan. Prostate specific membrane antigen (PSMA) targeting PET radiopharmaceuticals like [18F]DCFPyL may help detect disease not seen on CI. Our objective was to assess the ability of PSMA targeted PET/CT to detect sites of disease recurrence and impact on patient management. Methods: This multi-center prospective registry study included six Ontario centers. Eligible patients in 1 of 7 clinical cohorts (Table) were identified and approved by Cancer Care Ontario (CCO) to have restaging with PSMA targeted PET/CT. Referring physicians were asked to complete a form indicating whether a change in management strategy would occur based on the PET/CT results. At 6 months post-PET/CT, actual patient management will be confirmed via provincial registries. These interim results are from a single center. Results: 253 patients were enrolled and had a PSMA targeted PET/CT. At baseline, median age was 71 years (range 50-102 years) and median PSA was 2.7 ng/mL (range 0.04-134.0 ng/mL). The majority of patients (n=59; 23.3%) were in cohort 2 (biochemical failure post-RP). In patients with negative CI, PSMA targeted PET/CT detected disease sites in 68.5% (170/248), resulting in a change in management for 67.8% (137/202) overall and 72.1% and 64.3% post-RT and post-RP, respectively. Conclusions: PSMA targeted PET/CT detected occult lesions on CI in the majority of patients enrolled, leading to a high rate of change in management. Our institutional results are in keeping with preliminary results reported for the provincial cohort. Clinical trial information: NCT03718260. [Table: see text]

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Comparison of recurrence patterns after surgery and radiation therapy with 68Ga-PSMA-11 PET/CT in nonmetastatic castrate-sensitive prostate cancer patients: A single-center post-hoc retrospective analysis in 787 patients.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.3577 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. 3577-3577

Author(s):

Wesley R Armstrong ◽

Pan Thin ◽

Kathleen Nguyen ◽

Rejah M. Alano ◽

Kiara M Booker ◽

...

Keyword(s):

Prostate Cancer ◽

Radiation Therapy ◽

Lymph Node ◽

Retrospective Analysis ◽

Recurrent Disease ◽

Psma Pet ◽

Pet Ct ◽

Definitive Therapy ◽

Recurrence Patterns ◽

Post Hoc

3577 Background: 20 to 50% of prostate cancer (PCa) patients undergoing radical prostatectomy (RP) or definitive radiation therapy (dRT) will experience disease recurrence. However, anatomical recurrence patterns may differ depending on the therapeutic approaches. The aim of this post-hoc retrospective analysis was to investigate if the relapse pattern as assessed by 68Ga-PSMA-11 PET/CT was different depending on the type of local pelvic therapy (RP, dRT, salvage RT (SRT), pelvic lymph node dissection (PLND), pelvic lymph node RT (PLNRT)) in patients with non-metastatic castrate sensitive (nmCS) recurrent disease after primary definitive therapy. Methods: Patients who underwent a 68Ga-PSMA-11 PET/CT for nmCS PCa recurrent disease after primary definitive therapy were screened from a database of 4 prospective studies (NCT02940262, NCT03515577, NCT04050215, NCT03582774). Patients who underwent primary staging (n = 95), without definitive therapy (n = 68), with known metastatic disease (M1) (n = 68) or with castrate resistant (CR) disease (n = 291) were excluded. We examined the relationship between recurrence patterns as assessed by 68Ga-PSMA-11 PET/CT (PROMISE criteria) and prior local treatments: i) RP, ii) dRT, iii) RP + SRT. Results: 787 patients were included in the analysis. Positive scan rates were 60%, 94% and 75% in RP, dRT and RP + SRT populations, respectively. Median pre-scan PSA levels were 0.50 (0.02-72.5) ng/ml, 4.4 (0.1-202) ng/ml, and 1.07 (0.04-33) ng/ml for patients who underwent RP (n = 464), dRT (n = 109) and post-RP SRT (n = 214). Median time to first recurrence was 27.7 after RP and 54.6 months after dRT (p = < 0.0001). Patients who underwent RP had lower local recurrence (LR) pattern (T+) rates by PSMA PET than those with dRT (99/464; 21% vs 69/109; 63%; p = < 0.0001). Nodal metastasis (N1) positivity rate was similar between RP and dRT (179/464; 39% vs 43/109; 39%; p = 0.87). Extrapelvic metastasis (M1) positivity rate was lower for RP than dRT (93/464; 20% vs 51/109; 47%; p = < 0.0001). Median time from post-RP SRT to second recurrence was 22.3 months. In patients who had a second recurrence after RP and SRT the positivity rate of LR (T+), N1 disease and M1 disease by PSMA PET/CT was 12% (24/214), 46% (99/214) and 44% (95/214). Conclusions: In this cohort of patients with nmCS PCa recurrent disease after primary definitive therapy, the patterns of failure differ based on prior local treatments.

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