5318. Histopathologic and Imaging Predictors of PSMA-Positive Oligometastatic Prostate Cancer
Authors * Denotes Presenting Author
  1. Seyedeh Niloufar Rafiei Alavi *; University of California, Irvine
  2. Shawn Sun; University of California, Irvine
  3. James Shi ; University of California, Irvine
  4. Mark Tran; University of California, Irvine
  5. Vahid Yaghmai; University of California, Irvine
We sought to identify the risk factors associated with positive PSMA PET results in cases of oligometastatic disease.

Materials and Methods:
A retrospective analysis of 100 patients with recently diagnosed, high-risk prostate cancer who had undergone PSMA PET/CT scans for initial staging was conducted. Histopathological data were collected. Additionally, MRI data, such as PI-RADS score, PSA density, prostate size, lesion diameter, and contrast enhancement, were gathered. Logistic regression analysis was employed to identify predictors for the oligometastatic positive and control groups, aiming to pinpoint risk factors associated with PSMA PET positivity.

Out of the total 100 patients, 28 (28%) patients had oligometastatic disease, while 72 (72%) were negative for PSMA avid metastases. Biopsy and MRI records were available for 94 out of 100 patients and 82 out of 100 patients, respectively. The International Society of Urological Pathology (ISUP) grade group (15.53; [0.96, 2.44]) and the percentage of positive/total cores on biopsy (17.66; [1.63, 190.85]) were significant predictors of oligometastatic PSMA avid prostate cancer (OR; [95% CI]). Moreover, specific mpMRI-related parameters were also significant predictors of PSMA-positive oligometastases, including maximum prostate lesion diameter (1.05; 1.01, 1.1), number of intraprostatic lesions (17.66; 95% CI [1.64, 190.85]), and PSA density value (0.25 (ng/mL) ; [0.07, 0.89]). However, PI-RADS category did not serve as predictive factors for PSMA positivity.

This study underscores the importance of specific imaging and pathologic factors in predicting PSMA-positive oligometastatic prostate cancer. The results highlight the significance of higher pathological grading, larger intraprostatic tumor size, and elevated PSA concentrations in predicting early-stage oligometastatic disease in patients with high-risk prostate cancer.