FDG-PET/CT for lymph node staging prior to radical cystectomy

Area of Science:

• Oncology
• Nuclear Medicine
• Surgical Oncology

Background:

• Preoperative staging of bladder cancer with 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) before radical cystectomy (RC) is under investigation.
• Accurate lymph node staging is crucial for treatment planning and predicting outcomes in bladder cancer patients.

Purpose of the Study:

• To evaluate the accuracy of FDG-PET/CT for lymph node staging in bladder cancer patients undergoing RC.
• To compare FDG-PET/CT lymph node staging with pathological findings from surgical lymphadenectomy specimens.
• To identify factors contributing to false-positive FDG-PET/CT results in this patient cohort.

Main Methods:

• A study included consecutive bladder cancer patients undergoing RC with extended lymph node dissection between 2011 and 2019.
• FDG-PET/CT accuracy was assessed by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios.
• Potential factors for false-positive results, including bacteriuria, Bacillus Calmette-Guerin (BCG) treatment, and transurethral resection of bladder tumor (TURB), were investigated.

Main Results:

• Out of 157 patients, 44 (28%) were identified as clinically node-positive by FDG-PET/CT.
• The sensitivity for detecting lymph node metastasis was 50%, with a specificity of 84%.
• PPV was 61%, NPV was 76%, positive likelihood ratio was 3.0, and negative likelihood ratio was 0.6. No association was found between bacteriuria, BCG treatment, or TURB and false-positive FDG-PET/CT results.

Conclusions:

• Preoperative FDG-PET/CT demonstrates high specificity (84%) but limited sensitivity (50%) for detecting lymph node metastases in bladder cancer patients undergoing RC.
• The study did not identify specific factors associated with false-positive FDG-PET/CT findings.
• FDG-PET/CT may be a useful adjunct but should be interpreted cautiously due to its lower sensitivity in lymph node staging for bladder cancer.