Study Finds PSMA-PET May Hold Prognostic Utility in Prostate Cancer

In a study of high-risk patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) defined by conventional imaging methods, polymetastatic disease with 5 or more nodes based on prostate-specific membrane antigen ligand positron emission tomography (PSMA-PET) and initial pathological lymph node involvement (pN1) status were associated with significantly shorter overall survival (OS).¹

The findings were presented at the American Society of Clinical Oncology Annual Meeting and published in the Journal of Clinical Oncology.

In previous research, PSMA-PET identified distant metastases in more than half of patients with disease considered nmCRPC by conventional imaging, with 39% of patients showing distant nodes, 24% bone metastases, and 6% visceral organ metastases.² But the prognostic value of PSMA-PET disease extent and whether it impacts outcomes is not characterized, according to the authors of the current study.

The new analysis assessed the utility of PSMA-PET disease extent for OS and new metastases-free survival (nMFS) in patients with nmCRPC defined by traditional imaging.

A total of 200 patients with nmCRPC as determined by conventional imaging and prostate-specific antigen doubling time of 10 or fewer months and/or International Society of Urologic Pathologists grade group 4 or higher underwent PSMA-PET at 6 centers. Follow-up time ranged from 4-9 years, and patient data were analyzed retrospectively.

The median OS among all patients was 74 months, and polymetastatic disease with 5 or more lesions as determined by PSMA-PET was associated with shorter OS. Polymetastatic disease was also associated with shorter PSMA-PET nMFS. Metastatic disease by PSMA-PET with any lesions and whole-body PSMA tumor volume were not prognostic for OS, however. Initial pN1 status also showed an association with shorter OS, but not with PSMA-PET nMFS.

After PSMA-PET, disease was managed mostly with local or targeted therapy among patients who did not have locoregional or other visible disease, and patients with nodal or bone metastases were most often treated with androgen receptor signaling inhibition therapy.

Overall, the researchers concluded that 5 or more metastases as determined by PSMA-PET was significantly associated with OS, as was initial pN1 status, potentially providing a novel additional risk stratification measure in patients with nmCRPC who show no distant metastases in conventional imaging.

“Based on these findings, disease extent on PSMA-PET could represent a novel tool to risk stratify patients who have nmCROPC defined by cnventional imaging,” said lead study author Boris A. Hadaschik, MD, who presented the study. “PSMA-PET based disease extent and PSMA avidity may contribute to risk-adapted treatment after further validation of results.”

References

1. Hadaschik BA, Eiber M, Weber M, et al. Prostate-specific membrane antigen ligand positron emission tomography (PSMA-PET) disease extent and overall survival (OS) in patients (pts) with high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC): An international multicenter retrospective study.J Clin Oncol. 2023;41(suppl 16):5010. doi:10.1200/JCO.2023.41.16_suppl.5010

2. Fendler WP, Weber M, Iravani A, et al. Prostate-specific membrane antigen ligand positron emission tomography in men with nonmetastatic castration-resistant prostate cancer. Clin Cancer Res. 2019;25(24):7448-7454. doi:10.1158/1078-0432.CCR-19-1050