The Predictive Value of Preoperative Negative Prostate Specific Membrane Antigen Positron Emission Tomography Imaging for Lymph Node Metastatic Prostate Cancer

Abstract

Purpose: We sought to identify a subset of patients in whom an extended pelvic lymph node dissection during robot-assisted laparoscopic radical prostatectomy for localized prostate cancer could be omitted when preoperative prostate specific membrane antigen positron emission tomography showed no lymph node metastatic prostate cancer.

Materials and methods: A total of 434 patients who underwent prostate specific membrane antigen positron emission tomography prior to robot-assisted laparoscopic radical prostatectomy and extended pelvic lymph node dissection were retrospectively analyzed. Patients were excluded from analysis when the prostate specific membrane antigen positron emission tomography showed evidence of distant metastases. The primary outcome was whether a negative for metastases prostate specific membrane antigen positron emission tomography was able to correctly rule out pelvic lymp node metastases after extended pelvic lymph node dissection, ie its negative predictive value.

Results: Overall sensitivity, specificity, positive predictive value and negative predictive value of prostate specific membrane antigen positron emission tomography for the detection of pelvic lymp node metastases were 37.9%, 94.1%, 64.3% and 84.4%, respectively. The negative predictive value of prostate specific membrane antigen positron emission tomography in patients with intermediate risk prostate cancer was 91.6% (95% CI 86-97), compared to 81.4% (95% CI 77-86) in patients with high risk prostate cancer. When only assessing patients with <rT3 disease on multiparametric magnetic resonance imaging, 51/52 patients with intermediate risk prostate cancer had a true negative prostate specific membrane antigen positron emission tomography (negative predictive value=98.1%; 95% CI 94-100).

Conclusions: In patients with high risk prostate cancer, extended pelvic lymph node dissection remains the gold standard staging method, as pelvic lymph node metastases are frequently missed in those with no lymph node metastatic prostate cancer on prostate specific membrane antigen positron emission tomography. Patients with intermediate risk prostate cancer and a radiological T-stage <rT3 on multiparametric magnetic resonance imaging are potential candidates to withhold an extended pelvic lymph node dissection in the presence of a "negative for lymph node metastases" prostate specific membrane antigen positron emission tomography.

Keywords: lymph node excision; positron emission tomography computed tomography; prostatic neoplasms.