Number of metastatic lymph nodes as determinant of outcome after salvage radical prostatectomy for radiation-recurrent prostate cancer

Background Presence of lymph node metastasis (LNM) at salvage radical prostatectomy (sRP) is associated with poor outcome. Predictors of outcome in this context remain undetermined. The objective was to assess the role of number of positive lymph node on outcome of patients with LNM after sRP and for radio-recurrent prostate cancer. Material and methods We analyzed data from a consecutive cohort of 215 men treated with sRP at a single institution. We used univariate Cox proportional hazard regression models for biochemical recurrence (BCR) and metastatic outcomes, with prostate-specific antigen, Gleason score, extraprostatic extension, seminal vesicle invasion, time between radiation therapy and sRP, and number of positive nodes as predictors. Results Of the 47 patients with LNM, 37 developed BCR, 11 developed distant metastasis and 4 died with a median follow-up of 2.3 years for survivors. The risk of metastases increased with higher pre-operative PSA levels (HR 1.19 per 1 ng/ml; 95% CI 1.06–1.34; p = 0.003). The remaining predictors did not reach conventional levels of significance. However, removal of 3 or more positive lymph nodes demonstrated a positive association, as expected, with metastatic disease (HR 3.44; 95% CI 0.91–13.05; p = 0.069) compared to one or 2 positive nodes. Similarly, the presence of extraprostatic extension, seminal vesicle invasion and Gleason grade greater than 7 also demonstrated a positive association with higher risk of metastasis, with hazard ratios of 3.97 (95% CI 0.50, 31.4; p = 0.2), 3.72 (95% CI 0.80–17.26; p = 0.1), and 1.45 (95% CI 0.44–4.76; p = 0.5), respectively. Conclusions In patients with LNM after sRP for radio-recurrent prostate cancer, the risk of distant metastasis is likely to be influenced by the number of positive nodes (3 or more), high preoperative PSA, Gleason grade and advanced pathologic stage. These results are consistent with the findings of number of nodes (1 to 2 vs. 3 or more nodes positive) as a prognostic indicator after primary radical prostatectomy and strengthen the plea for a revision of the nodal staging for prostate cancer.