PSMA PET Imaging May Offer Key Prognostic Markers for Prostate Cancer

New research suggests that pelvic lymph node involvement and polymetastatic disease detected by prostate-specific membrane antigen (PSMA)/ positron emission tomography (PET) are associated with a significantly worse prognosis in patients initially diagnosed with non-metastatic castration-resistant prostate cancer (nmCRPC).

In multicenter research presented at the American Society of Clinical Oncology (ASCO) conference and recently published in the Journal of Clinical Oncology, researchers reviewed PSMA/PET scans for 200 patients who were initially diagnosed via conventional imaging with nmCRPC. These patients also had an International Society of Urological Pathology (ISUP) grade 4 or higher, and/or a prostate-specific antigen doubling time (PSADT less than or equal to 10 months, according to the study.

The study authors found that polymetastatic disease (five or more polymetastases) on PSMA PET imaging had a 1.93 hazard ratio (HR). While the median overall survival rate and metastases-free survival rate (nMFS) for the cohort were 74 months and 60 months, respectively, the researchers found that those with polymetstatic disease had a median overall survival rate of 61 months and a 38-month nMFS.

Initial pelvic lymph node involvement had no impact on the nMFS rate, according to the study authors. However, they did note a significant association with a shorter mean overall survival rate (2.01 HR). Patients with initial pelvic lymph node involvement had a median overall survival rate of 55 months in comparison to the aforementioned 74-month overall survival rate in the cohort.

“PSMA-PET disease extent provides a potential novel additional risk stratification for (patients) with nmCRPC without distant metastasis based on conventional imaging,” wrote Wolfgang Fendler, M.D., who is affiliated with the Department of Nuclear Medicine at the University of Duisburg-Essen and the German Cancer Consortium (DKTK) at University Hospital Essen in Essen, Germany, and colleagues.

While the researchers noted a 1.58 HR in patients with prior definitive radiotherapy (RT) and a 1.41 HR for those with a Gleason grade greater than or equal to eight, they noted these factors had no significant impact on overall survival rates. The PSA level and PSADT also had no impact on survival rates, according to the study authors.

(Editor’s note: For related content, see “Emerging Nomogram May Predict Outcomes After PSMA PET-Guided Salvage Radiotherapy in Patients with Prostate Cancer” and “FDA Approves New PSMA PET Agent POSLUMA for Prostate Cancer Imaging.”)