ASTRO research demonstrates the management of high-risk prostate cancer with PSMA PET / CT

Researchers at the ASTRO 2020 virtual annual meeting are publicizing a new study demonstrating the ability of PSMA PET / CT to distinguish between localized and metastatic cases of high-risk prostate cancer.

Staging of the disease is currently done with the use of a CT scan, usually of the abdomen and pelvis, and a technetium bone scan. The authors state that the results of their post hoc analysis show the effective role that PSMA PET / CT plays in the management of high-risk prostate cancer. The title of the study is Impact of 68Ga-PSMA-11 PET / CT on Initial Staging of Patients with High-Risk Prostate Cancer: Post-hoc Analysis of One-Center Prospective Experience on the Impact of PSMA PET / CT Staging in Men with Prostate Cancer high risk NCCN.

“Conventional imaging for the initial staging of prostate cancer (PCa) lacks sensitivity and underestimates the disease burden,” the authors said in their study. “PET / CT prostate-specific membrane antigen (PSMA PET) is an emerging imaging modality that has been shown to have improved sensitivity over conventional imaging in the context of biochemical recurrence.”

The study evaluated 249 NCCN high / very high-risk PCa patients undergoing PET imaging with PSMA in a prospective study between December 2016 and January 2020. PSMA PET exceeded 22.9% of patients, with 18.9% diagnosed with disease iN0 by CT or MRI found to have disease N1 and 10.6% who were given disease status M0 by CT or bone scan now given disease status M1. Meanwhile, 7.4% received new M1a disease and 5.3% had M1b / M1c disease. In addition, PSMA PET detected ECE (local spread of cancer beyond the prostate), seminal vesicle invasion, or invasion of surrounding structures in 8.1% of patients classified as T2 on prior MRI imaging.

Those with a grade group of five or ≥50% percent positive biopsy nuclei (PPC) were more likely to have regional nodal stage and any upstage overall, while patients with GG 5 along with PPC ≥50 were expected % had an upstage M stage. cT and iPSA were not associated with upstaging.

While increasing availability worldwide due to its higher sensitivity and specificity than conventional imaging, PSMA PET / CT is still limited in use, even in the United States where the FDA has not yet approved the agent.

Overall, PSMA PET / CT identified 19.7% of patients with regional PET positive lymph node disease and 9.4% with PET / CT metastatic disease. While they are not uniformly biopsy-tested areas for metastatic disease, it is possible, based on previous research, that 85% -98% of the lesions found in these areas are likely prostate cancer, according to Dr. Daniel Spratt. a University of Michigan radiation therapist who saw the presentation. He adds that the results show that GG 5 (Gleason score of 9-10) and> 50% of the biopsy nuclei involved with cancer are predicted for non-localized prostate cancer.

“Based on clinical studies conducted by UCLA, UCSF and other centers, I hope these molecular imaging modalities can soon be added to our toolbox to better customize our treatments,” Spratt wrote in an ASTRO editorial.

The results were published in International journal of oncological radiotherapy · Biology · Physics.