MP14-19 LYMPH NODE METASTASES IN GLEASON ≤ 6 PROSTATE CANCER: DATA FROM A GERMAN MULTICENTER DATABASE

INTRODUCTION: Lymph node involvement (LNI) in prostate cancer with a Gleason score (GS) 6 or less is very rare and some authors have concluded that pelvic lymph node dissection (PLND) can regularly be omitted if the GS of the needle biopsy (NB) specimen is ≤ 6. Objective of our study was to analyze data from a multicenter cohort regarding the incidence of LNI in GS ≤ 6 prostate cancer. METHODS: Data was obtained from the onlinedatabase www.prostata-ca.net. Descriptive statistics were calculated using SPSS 22. RESULTS: 9,511 Patients had been treated by RP and PLND in the years 1994 to 2015. While 3,513 (36.9%) were initially diagnosed with a GS ≤ 6 by NB, only 1,831 (19.3%) actually had a GS ≤ 6 in the RP specimen. Significant upgrading (GS ≤ 6 to GS ≥ 7) occurred in 1,984 (20.8%) of all cases. LNI was present in 944 cases (9.9%) overall. Prevalence of LNI in patients with a GS ≤ 6 in the NB specimen was 2.4% compared to 0.2% if the GS ≤ 6 was confirmed in the RP specimen. CONCLUSIONS: LNI in low grade prostate cancer is rare (3 cases, 0.2%). However, 81 patients with LNI showed a GS ≥ 7 at final diagnosis, but were initially graded as GS ≤ 6 in the NB specimen. Significant undergrading of the NB specimen was common and occurred in more than half of all patients with a GS ≤ 6 in the biopsy. Our study demonstrates that, especially outside of highly specialized centers, undergrading of NB specimen is still common and the malignant potential of some cancers is thus discovered only after RP and PLND. More reliable tools for pretreatment riskstratification are warranted. Treated by RP + PLND 9,511 Initial PSA: Median (Mean) ng/ml PSA > 10 ng/ml 103 missing 8.05 (12.31) 3,553 (37.8%) Clinical Stage: cT1 cT2 cT3/4 505 missing 5,300 (58.8%) 3,340 (37.1%) 366 (4.1%) Gleason score NB Gleason ≤ 6 Gleason 7 Gleason ≥ 8 3,513 (36.9%) 4,224 (44.4%) 1,774 (18.7%) Gleason score RP Gleason ≤ 6 Gleason 7 Gleason 8 1,831 (19.3%) 6,000 (63.1%) 1,680 (17.7%) Grade-shift NB-RPE No Grade-Shift Upgrading total Downgrading total Upgrading GS ≤ 6 to ≥ 7 5,525 (58.1%) 2,802 (29.5%) 1,184 (12.4%) 1,984 (20.8%) LNI No LNI LNI inconclusive 944 (9.9%) 8,399 (88.3%) 168 (1.7%) Pathological stage pT1 pT2 pT3/pT4 24 missing 16 (0,2%) 5,715 (60.2%) 3,756 (39.6%) Abstract ID: 15-2961 GS NB ≤ 6 Total 3,513 LNI 83 GS RP ≤ 6 GS RP = 7 GS RP ≥ 8 1,529 (43.5%) 1,822 (51.7%) 162 (4.6%) 2 (2.4%) 59 (71.1%) 22 (26.5%) Upgrading 2,110 (60.1%) 82 (98.8%) Downgrading 137 (3.9%) 1 (1.2%) Sign. Up. 1,984 (56.5%) 81 (97.6%) primary treatment cases: 18,311 no GS of RP: 3,455 no RP: 554 14,302 treated by RP and GS available no GS of NB available: 1,437 12,865 with GS of RP and NB available PLND inconclusive: 1,156 PLND: 9,515 implausible data: 4 9,511 cases for data analysis