Genitourinary Cancer

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

1005 - Employing Molecular Imaging to Understand Tumor Genetic Risk Scores: PSMA Nodal Involvement Associated with High-Risk Decipher in Prostate Cancer

Sunday, October 21
1:58 PM - 2:04 PM
Location: Room 217 A/B

Employing Molecular Imaging to Understand Tumor Genetic Risk Scores: PSMA Nodal Involvement Associated with High-Risk Decipher in Prostate Cancer
M. J. Xu1, Z. Kornberg2, A. Gadzinski3, D. Diao1,4, J. Cowan3, S. Y. Wu5, L. Boreta1, D. E. Spratt6, H. Nguyen3, M. Roach III1, T. Hope7, P. Carroll3, and F. Y. Feng8; 1University of California San Francisco, Department of Radiation Oncology, San Francisco, CA, 2University of California San Francisco School of Medicine, San Francisco, CA, 3University of California San Francisco, Department of Urology, San Francisco, CA, 4First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China, 5University of California, San Francisco, San Francisco, CA, 6Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 7University of California San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA, 8Department of Radiation Oncology, University of California San Francisco, San Francisco, CA

Purpose/Objective(s): The Decipher 22-gene genomic classifier (GC) is increasingly used to estimate risk for distant metastases in men who have undergone local therapy for prostate cancer (PCa). Whether high-risk GC scores are associated with occult metastatic disease at presentation or subsequent development of metastatic disease following definitive therapy is unknown. We leveraged patients undergoing both the GC test and Prostate Specific Membrane Antigen (PSMA) PET imaging to investigate associations between the location and timing of metastases in men with high-risk GC scores.

Materials/Methods: Between December 2015 and December 2017, 82 patients with PCa with both GC scores and pre-treatment Gallium-68 PSMA PET scans were identified. Risk stratification by the National Comprehensive Cancer Network (NCCN), CAPRA, and GC scores were performed. Univariable binary logistic regression was used incorporating each risk stratification method to identify factors correlated with PSMA-positive disease.

Results: Of 82 PCa patients, 20 (24.4%) and 62 (75.6%) patients were NCCN intermediate and high risk, respectively; 4 (4.9%), 20 (24.4%), and 58 (70.7%) were CAPRA low, intermediate, and high risk. In contrast, only 38 (46.3%) were classified as having high-risk GC scores. PSMA-avid disease was present in the prostate gland in 80 patients (97.6%). PSMA-avid pelvic nodal involvement was identified in 24 (29.3%) patients, 9 of which (37.5%) would not have had been detected by standard imaging work-up (size ≥ 0.8 cm). Pelvic nodal involvement was correlated with high-risk GC scores (OR 3.3, p=0.02). Unsurprisingly, it was also associated with high-risk NCCN (OR 5.0, p=0.04), high-risk CAPRA (OR 4.0, p=0.04), higher pre-treatment PSA (OR 1.03, p=0.04), cT3-4 disease (OR 3.7, p=0.02), and higher Gleason score (OR 1.7, p=0.047). PSMA-avid metastatic nodal disease was found in 5 (6.1%) patients and significantly associated with high-risk GC scores (p=0.02), but not with NCCN or CAPRA grouping, pre-treatment PSA, cT3-T4 disease, or Gleason score. Any nodal PSMA-avid disease (pelvic or distant) was also significantly associated with high-risk GC scores (OR 4.1, p=0.006). PSMA-avid osseous metastases were found in 12 (14.6%) patients and not correlated with high-risk GC scores.

Conclusion: In clinically intermediate- to high-risk PCa patients, high-risk GC scores were predictive for PSMA-avid pelvic and metastatic lymph node involvement. This suggests the Decipher test may predict for distant disease by means of initial nodal involvement and that high-risk GC patients may benefit from more aggressive nodal management through pelvic nodal dissection or irradiation, or possibly the addition of novel next generation hormonal agents.

Author Disclosure: M.J. Xu: None. Z. Kornberg: None. A. Gadzinski: None. J. Cowan: None. L. Boreta: None. M. Roach: Honoraria; Ferring Pharma, Blue Earth, Myriad. Consultant; Ferring Pharma, Janssen Pharma, International Atomic Energy Agency. Advisory Board; Janssen Pharma, Tolmar, Bayer, Blue Earth, Myriad. Travel Expenses; Ferring Pharma, Janssen Pharma, International Atomic Energy Agency, Tolmar, Bayer, Blue Earth, Myriad. Stock; Abbott, Agilent, Altria, GSK, Hospira. Board Member; NCAB. T. Hope: Research Grant; GE Healthcare. P. Carroll: Research Grant; Genomic Health International, Myriad. Honoraria; Genomic Health International, Janssen, Takeda. Advisory Board; Genomic Health International. Board of Directors; National Comprehensive Cancer Network. F.Y. Feng: Research Grant; GenomeDx. Advisory Board; GenomeDx, Dendreon, Sanofi. Travel Expenses; GenomeDx. Liaison, GU Translational Research Program; Radiation Therapy Oncology Group. President and Founder; PFS Genomics.

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