Association between Lymph Node Counts and Oncological Outcomes in Lymph Node Positive Prostate Cancer

Abstract

Background: While the diagnostic value of pelvic lymph node dissection (PLND) during radical prostatectomy (RP) is undisputed, its therapeutic benefit remains a matter of debate.

Objective: To investigate the association between total and positive lymph node (LN) counts and oncological outcomes in pN1 patients at RP.

Design, setting, and participants: The records of 706 LN-positive patients undergoing RP and PLND between 1998 and 2012 in a single center were analyzed. The median follow-up was 47.8 mo.

Intervention: RP and PLND.

Outcome measurements and statistical analysis: The number of harvested and positive LNs and their influence on biochemical recurrence-free survival, metastasis-free survival, and cancer-specific survival was evaluated using univariate and multivariate Cox regressions. The number of harvested LNs was used as a continuous and dichotomous variable with a cut-off of 13 LNs.

Results and limitations: The mean (median) number of removed LNs was 15.0 (13) and the mean (median) number of positive LNs was 2.4 (1). In multivariate analysis, the number of removed LNs did not significantly influence oncologic outcomes (biochemical recurrence, metastasis-free survival, or cancer-specific survival). The occurrence of metastasis and cancer-specific mortality significantly increased with higher number of positive LNs. The main limitation was the retrospective nature of the study.

Conclusions: While a higher number of positive LNs were significantly associated with worse oncological outcomes, the number of removed LNs was not a significant predictor.

Patient summary: We found that only the number of positive lymph nodes (LNs) but not the total number of removed LNs was a factor adversely influencing oncological outcomes in LN-positive patients undergoing radical prostatectomy.

Keywords: Lymph node dissection; Positive lymph nodes; Prostate cancer; Radical prostatectomy.