Pelvic Lymph Node Staging With PSMA PET in Prostate Cancer: Surgical Validation With Implications for Radiotherapy...

Area of Science:

• Oncology
• Radiology
• Nuclear Medicine

Background:

• Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is integral to pelvic nodal staging in prostate cancer.
• Its negative predictive value for microscopic nodal disease is not absolute.
• This study validates PSMA PET/CT findings against surgical histopathology.

Purpose of the Study:

• To determine the actual rate of occult pelvic lymph node metastases in prostate cancer patients with negative PSMA PET/CT scans.
• To assess the reliability of PSMA PET/CT for excluding microscopic nodal disease.
• To identify factors associated with false-negative PSMA PET/CT results.

Main Methods:

• Retrospective analysis of 51 intermediate- to high/very high-risk prostate cancer patients.
• All patients had negative preoperative ⁶⁸Ga-PSMA PET/CT for pelvic lymph nodes.
• Radical prostatectomy with extended pelvic lymph node dissection was performed; histopathology (pN) was the reference standard.

Main Results:

• Histopathology revealed pelvic lymph node metastases in 6 of 51 patients (11.8%) despite negative PSMA PET/CT.
• Patients with positive nodes (pN+) were significantly older and had higher preoperative PSA levels.
• Higher preoperative nodal risk scores correlated with pN+ status.

Conclusions:

• A negative PSMA PET/CT scan does not reliably rule out microscopic pelvic lymph node metastases in prostate cancer.
• The study demonstrates a significant false-negative rate for PSMA-based nodal staging.
• Findings support a cautious, risk-adapted approach to treatment de-escalation in patients with negative PSMA PET/CT.