Does increasing the nodal yield improve outcomes in contemporary patients without nodal metastasis undergoing radical prostatectomy?

Objectives: To determine if the number of lymph nodes (LNs) removed is an independent predictor of biochemical recurrence (BCR) in patients without LN metastases undergoing radical prostatectomy (RP). Material and methods: Retrospective analysis of 7,310 patients treated at 7 centers with RP and pelvic LN dissection for clinically localized prostate cancer between 2000 and 2011. Patients with LN metastases (n = 398) and other reasons (stated later in the article) (n = 372) were excluded, which left 6,540 patients for the final analyses. Results: Overall, median biopsy and RP Gleason score were both 7; median prostate specific antigen level was 6. ng/ml (interquartile range [IQR]: 5); and median number of LNs removed was 6 (IQR: 8). A total of 3,698 (57%), 2,064 (32%), and 508 (8%) patients had ≥6, ≥10, and ≥20 LNs removed, respectively. Patients with more LNs removed were older, had a higher prostate specific antigen level, had higher clinical and pathologic T stage, and had higher RP Gleason score (all P<0.002). Within a median follow-up of 21 (IQR: 16) months, more LNs removed was associated with an increased risk of BCR (continuous: P = 0.021; categorical: P = 0.014). In multivariable analyses that adjusted for the effects of standard clinicopathologic factors, none of the nodal stratifications predicted BCR. Conclusions: The number of LNs did not have any prognostic significance in our contemporary cohort of patients with LN-negative prostate cancer. This suggests that the risk of missed clinically significant micrometastasis may be minimal in patients currently treated with RP and having a lower LN yield.