Genitourinary Cancer

PD 01 - GU 1 - Poster Discussion - New Data on PET, MRI and Protons for Treating Prostate Cancer

1000 - The Impact of 18F-Fluciclovine Positron Emission Tomography on Salvage Radiation Therapy Decisions for Patients with Post-Radical Prostatectomy Recurrence of Prostate Cancer: Results from LOCATE

Sunday, October 21
1:15 PM - 1:21 PM
Location: Room 217 A/B

The Impact of 18F-Fluciclovine Positron Emission Tomography on Salvage Radiation Therapy Decisions for Patients with Post-Radical Prostatectomy Recurrence of Prostate Cancer: Results from LOCATE
A. A. Solanki; Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL; Loyola University Medical Center, Maywood, IL

Purpose/Objective(s): Standard imaging infrequently localizes lesions responsible for biochemical recurrence (BCR) of prostate cancer in men undergoing evaluation for salvage radiation therapy (RT) after radical prostatectomy (RP). Given the high risk of local failure, radiation oncologists typically target the prostate bed (PB) ± pelvic lymph nodes (LNs). LOCATE (NCT02680041) was a prospective clinical trial examining the impact of positron emission tomography/computed tomography (PET/CT) with novel radiotracer, 18F-fluciclovine, on management of men with BCR of prostate cancer after curative-intent treatment. Here, we report the impact of 18F-fluciclovine PET/CT on salvage RT decisions in post-RP patients.

Materials/Methods: Eligibility criteria were: ≥ 18 y; prior curative-intent treatment of prostate cancer; BCR (defined as PSA ≥ 0.2 ng/mL after RP); negative/equivocal findings on both whole-body 99mTc-MDP bone scintigraphy (or 18F-fluoride PET/CT) and pelvic CT or MRI. 18F-Fluciclovine PET/CT was performed and interpreted according to standardized procedures at 15 US centers. Physicians completed a questionnaire about a patient’s treatment plan, pre- and post-scan. The primary endpoint was the proportion of patients with an altered plan post-scan.

Results: Between June 2016 and May 2017, 213 patients (median pre-scan PSA, 1.00 ng/mL) were enrolled. In total, 164 had RP as initial therapy, 114 of whom were scheduled to undergo salvage RT at the time of enrollment. Post-scan, 54/114 (47%) patients had a change in management, 35 (65%) of whom had a change to treatment modality: 17 to systemic therapy, 13 to watchful waiting, 5 other. An additional 19 (35%) had RT fields modified: PB alone expanded to whole pelvis or to include a boost to a lesion identified by 18F-fluciclovine PET/CT (n = 11); whole pelvis reduced to only PB ± boost to PET-positive areas (n = 4); boosts based on conventional imaging were removed or refocused on PET-positive areas (n = 4). The table presents the fluciclovine detection rate (DR) at subject and region level for all 114 patients, as well as in those whose management changed post-scan.
DR, n (%)
All N = 114 Modality change n = 35 (31) RT field change n = 19 (17)
Subject levelA 48 (42) 18 (51) 15 (79)
PB 20 (18) 6 (17) 5 (26)
ExtraprostaticB 36 (32) 16 (46) 13 (68)
Pelvic LNs 22 (19) 11 (31) 9 (47)
Retroperitoneal LNs 9 (7.9) 7 (20) 2 (11)
Bone 13 (11) 5 (14) 3 (16)
Other non-bone metastases 3 (2.6) 1 (2.9) 1 (5.3)
AAny prostatic or extraprostatic lesion BAny lesion in the LNs, soft tissues, or bone

Conclusion: Almost half of men with BCR scheduled to undergo salvage RT after RP had positive 18F-fluciclovine PET/CT despite negative standard imaging. Planned salvage RT was frequently changed to another modality and RT fields were modified for one fifth of patients. Investigation of the clinical outcomes of these changes is warranted.

Author Disclosure: A.A. Solanki: Consultant; Blue Earth Diagnostics. Advisory Board; Blue Earth Diagnostics.

Abhishek Solanki, MD, MS

Loyola University Medical Center

Disclosure:
Employment
Loyola University Medical Center: Attending Physician: Employee

Compensation
Blue Earth Diagnostics: Advisory Board, Consultant, Honoraria, Travel Expenses

Presentation(s):

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