Previous studies highlighted the characteristics of the metastatic focus of prostate cancer (PCa) in pelvic lymph nodes (LN) as variables that could affect the outcome of radical prostatectomy. In addition, in recent years, the adoption of the surgical extended pelvic LN dissection has resulted in an increase in the rate of detection of LN metastasis. The goal of our study was to determine the prognostic value of the number of positive LN, extranodal extension (ENE), and the size and Gleason Grade (GG) of metastatic foci in prostate cancer.
In this study, we evaluated the effect of the features of LN metastasis on the risk of biochemical recurrence (BCR) in 280 LN-positive patients who underwent radical prostatectomy between 2006 to 2018. The characteristics of the LN metastasis included a solitary positive LN in 59%, 2-4 positive LNs in 34%, and 5 or more in 7% of the patients. The metastatic focus was > 2 mm (macrometastasis) in 154/261 (59%). GG of the metastatic focus was as follows: GG 1-2: 29/224 (13%); GG 3: 27/224 (12%); and GG 4-5: 168/224 (75%). ENE was identified in 99/244 (41%). We found the number of LNs positive (2-4 vs. 1 Hazard ratio (HR) = 1.60; 95% CI: 1.02 to 2.5; P = 0.04) and GG of the metastatic focus (GG 4&5 vs. 1-3 HR = 1.90; 95% CI: 1.14-3.2; P= 0.014) to be independent predictors of the risk of biochemical recurrence (BCR) after surgery on multivariate analysis.
Based on our analysis, we demonstrated that the number of positive LN(s), and GG of metastatic focus to be significant predictors of BCR. LN metastasis can be stratified into favorable and unfavorable groups based on these histomorphogic features within LN(s). Larger prospective studies with longer follow-up are needed to further evaluate the need to incorporate features of the LN metastasis into the TNM staging.
Written by: Shaheen Alanee, MD, MPH, MBA, FACS, FRCSC, Senior staff – Detroit Medical Center, Associate Professor of Urology – Michigan State University
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