The extent of lymphadenectomy for pTXNO prostate cancer does not affect prostate cancer outcome in the prostate specific antigen era

Purpose: Recent data suggest that extended lymph node dissection in prostate cancer may be necessary for accurate staging. With limited lymph node dissection apparently node negative cases might be under staged. We determined the impact that the number of lymph nodes removed at radical retropubic prostatectomy (RRP) has on cancer progression and cause specific survival in pTXNO cases. Materials and Methods: We reviewed the RRP prostate cancer database on 7,036 patients with clinical T1 to T3 disease, no adjuvant therapy and node negative disease in the prostate specific antigen (PSA) era from 1987 to 2000. Factors evaluated were the number of lymph nodes obtained at RRP, preoperative PSA, clinical and pathological stage and grade, margin status, year of surgery and specific surgeon for 5 surgeons who operated throughout the period and performed more than 500 RRPs. Cox analysis was done to determine the RR of progression (PSA or systemic) and prostate cancer death for the number of lymph nodes excised. Results: Median patient age was 65 years and median preoperative PSA was 6.6 ng/ml. At pathological evaluation 5,379 tumors (77%) were organ confined, 4,491 (65%) were Gleason score 5 to 6 and 2,027 (29%) were Gleason score 7 to 10. The median number of nodes obtained significantly decreased from 14 in 1987 to 1989 to 5 in 1999 to 2000 (p <0.001). Ten years after RRP Kaplan-Meier estimates were 63% of cases free of PSA progression, 95% free of systemic progression and 98% free of prostate cancer related death. Median followup was 5.9 years. After adjusting for pathological factors (PSA, grade, stage, margin status and surgical date) the number of lymph nodes obtained at lymphadenectomy was not significantly associated with PSA progression (for each additional node (RR 0.99, 95% CI 0.98 to 1.02, p = 0.90), systemic progression (RR 0.99, 95% CI 0.96 to 1.03, p = 0.68) or cause specific survival (RR 1.01, 95% CI 0.96 to 1.06, p = 0.75). Conclusions: The extent of lymphadenectomy does not appear to affect prostate cancer outcome in lymph node negative cases. This includes patients with high preoperative PSA, high pathological grade and extracapsular disease. These results suggest that under staging is not present in apparently node negative cases with limited lymphadenectomy and, even if present, its impact on outcome is likely to be negligible.