Risk of lymph node metastases in pathological gleason score≤6 prostate adenocarcinoma: Analysis of institutional and population-based databases.

INTRODUCTION: Several institutional studies have suggested that pathological Gleason score≤6 prostate cancer has little or no capacity for metastasis.

MATERIALS AND METHODS: Using the Surveillance, Epidemiology, and End Results database (SEER, 2004-2011, n = 19,594) and the National Cancer Database (NCDB, 2004-2013, n = 57,540), we identified patients with pathological Gleason score≤6 prostate cancer following radical prostatectomy and lymph node dissection. At the University of Chicago Medicine (UCM, 2003-2014), we considered men with Gleason score≤6 prostate cancer who did (n = 267) and did not receive (n = 770) a lymph node dissection at the time of radical prostatectomy. Temporal trends in lymph node dissection and lymph node metastases were determined, and multivariable logistic regressions were used to analyze factors associated with lymph node metastases. In the UCM cohort, we also evaluated secondary endpoints, including biochemical recurrence (BCR), metastatic disease on follow-up imaging, and response to salvage radiation therapy.

RESULTS: The incidence of lymph node dissection at the time of radical prostatectomy decreased from 60% to 37% in SEER (2004-2011) and from 62% to 45% in NCDB (2004-2013). Positive lymph node metastases were found in 0.2% of SEER and 0.18% of NCDB patients who received a lymph node dissection. Elevated PSA, higher clinical stage, and African American race were associated with lymph node positivity in one or both of these databases (P<0.05). Among UCM patients who received a lymph node dissection, no lymph node metastases were found, though a BCR occurred in 3 cases (1%). All 3 men responded favorably to salvage therapy, suggestive of local recurrence. A total of 21 patients (3%) from UCM who did not receive a lymph node dissection had a BCR and underwent salvage radiation therapy. Of these, 4 patients had persistently detectable PSA levels without evidence of local or distant disease at median follow-up of 65 months (range: 29-79) following salvage therapy. Surgical specimens were available for contemporary pathologic review in 3 of these cases, and all were upgraded to Gleason 7 disease.

CONCLUSIONS: Our population-based and institutional analyses suggest metastases in cases of Gleason score≤6 prostate cancer to be extremely rare.