Does the Number of Lymph Nodes Removed During Radical Prostatectomy Impact Risk of Biochemical Recurrence in Patients With Isolated Seminal Vesicle Invasion?

Objectives: To determine if greater lymph node yield (LNY) during radical prostatectomy is associated with improved biochemical recurrence for men with prostate cancer and isolated seminal vesicle invasion (SVI). Previous studies have shown that total number of lymph nodes removed at RP results in improved survival, regardless of node positivity, but this has not been examined in men with isolated SVI. Methods: The IRB-approved Columbia University Urologic Oncology Database was reviewed to identify patients who underwent RP from 1990-2011 and had prostate cancer with isolated SVI (i.e. pT3bN0Mx). BCR was defined as two postoperative PSA values >0.2 ng/mL. Cox proportional hazards model was used to determine if LNY (continuous) was predictive of BCR, when controlling for clinical and pathologic features. Results: We identified 155 patients with isolated SVI. At a mean follow-up of 48 months, 96 patients (62.5%) experienced BCR. Estimated 5-year freedom from BCR rate was 45%. Mean number of LNs removed was 8.9 (1-35). Using the Cox proportional Hazards model, continuous LNY was not significantly associated with risk of BCR (p=0.25), while PSA (HR 2.3, p=0.01), pathologic Gleason score (p=0.023), and bladder neck invasion (p=0.04) were significant. Conclusion: Seminal vesicle invasion after radical prostatectomy is associated with a high risk of BCR, even in the absence of positive surgical margins or lymphatic involvement. Our study demonstrates that the lymph node yield at the time of prostatectomy does not affect the risk of BCR in men with node-negative SVI. Further studies are warranted to evaluate cancer-specific and overall survival.