Prognostic significance of lymph node count in D’Amico high risk prostate cancer with different lymph node metastasis risks after radical prostatectomy

Abstract Extended pelvic lymph node dissection (PLND) is recommended in high risk prostate cancer (PCa). We aim to identify the prognostic significance of removed lymph node count (RLNC) for patients with D’Amico high risk PCa and different lymph node metastasis risk (LNMR). We identified surgically treated D’Amico high risk PCa patients with the Surveillance, Epidemiology, and End Result (SEER) Plus database (2004-2019). Multivariable logistic regression model was established to predict lymph node metastasis risk (LNMR) in patients with RLNC over 6. Multivariable Cox regression analysis were used to assess the impact of RLNC on cancer-specific survival (CSS) and overall survival (OS). A total of 96875 patients were identified. 5261 patients (5.43%) had LN metastasis. The median and 75th percentile RLNC was 6 and 11. LNMR was calculated for every patients and all the patients were divided into four subgroups: LNMR<0.1, 0.1≤LNMR<0.2, 0.2≤LNMR<0.3, LNMR≥0.3. Multivariable Cox regression analysis showed that more RLNC was associated with better CSS and OS in LNMR≥0.3 subgroup (CSS: HR 0.78 (0.63, 0.96) p=0.0213 for cutoff 11 RLNC; OS: HR 0.85 (0.72, 0.99) p=0.0407 for cutoff 11 RLNC, HR 0.9891 (0.9796, 0.9987) p=0.0256 for continuous RLNC). More RLNC is associated with better CSS and OS when the LNMR is over 30%.