PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): [18F]-DCFPyL is a second generation positron emission tomography (PET) probe targeting PSMA - a trans-membrane protein overexpressed in prostate cancer. PICs seeks to evaluate [18F]-DCFPyL PET/CT in restaging men with biochemical failure (BF) after primary radiation therapy.
Materials/Methods: PICs (NCT02793284) is a prospective, single arm study conducted at four cancer centers in Ontario of men with BF (Phoenix definition) after primary radiation for localized (T1/T2, Gleason ≤8, PSA≤20) prostate cancer. Participants undergo conventional imaging (CI: computed tomography (CT) thorax/ abdomen/ pelvis, bone scan, and multiparametric MRI pelvis) followed by [18F]-DCFPyL PET/CT (PET). PET was reported by nuclear medicine physicians at each Cancer Center with central review. In cases of disagreement a third read is specified by the protocol. Primary endpoint is the proportion of men with metastatic disease detected by PET compared to CI. Secondary endpoints include number of lesions outside the prostate detected by PET compared to CI, and changes in patient management plan based on results of PET vs. CI.
Results: Since opening in January 2017, 50 of a planned 80 patients have been accrued; the first 35 patients are reported here. At enrollment, median age was 75, median PSA 7.1, median PSA doubling time was 11.0 months, and median time from end of definitive radiation treatment to BF was 65.4 months. Stage and grade at the time of definitive radiotherapy was T1 (18/35, 51%) or T2 (17/35, 49%) and Gleason 6 (9/35, 26%), 7(25/35, 71%), or 8 (1/35, 3%). Previous treatment included external beam radiotherapy (24/35, 69%) or brachytherapy (11/35, 31%). Overall, any site of recurrence was identified in 33/35 (94%) men by both CI and PET. Extra-prostatic metastases were detected in 10/35 (29%) patients by CI and in 13/35 (37%) by PET. Isolated intra-prostatic recurrence was identified by CI in 21/35 (60%); PET detected additional, unrecognized extra-prostatic metastases in 4/21 (19%). A change in management plan based on PET vs. CI occurred in 17/35 men (49%). Changes included the addition of salvage RT (8/17, 47%), ADT (4/17, 24%), biopsy (3/17, 18%), and HIFU (1/17, 6%).
Conclusion: For men with BF after primary RT, [18F]-DCFPyL PET/CT detects additional sites of disease that result in changes in management compared to CI. Identification of extra-prostatic metastases among men where CI identifies isolated intra-prostatic recurrence suggests a role for [18F]-DCFPyL PET/CT in optimizing selection for local salvage treatments. Updated results will be presented.
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