Absence of independent prognostic impact of node status in M1 prostate cancer: implications from a SEER-based study.

[OBJECTIVE] We aimed to evaluate the association between T stage, N stage, and Gleason score with OS in metastatic prostate cancer (mPCa) patients.

[METHODS] Using the SEER database, we identified M1 prostate cancer patients. Kaplan-Meier survival analysis with Log-rank testing was performed, stratified by metastatic substages (M1a, M1b, M1c). Multivariable Cox regression models identified independent prognostic factors for overall survival (OS).

[RESULTS] A total of 170 mPCa patients were included, 60.0% had Gleason score ≥ 8, 74.7% presented with T3-T4 disease (versus 25.3% with localized T1-T2 tumors), and metastatic distribution included 68.8% M1b, 17.6% M1a, and 13.5% M1c. M1c patients demonstrated significantly worse prognosis (p = 0.033). Subgroup analyses revealed that advanced T stage significantly correlated with reduced OS in the overall M1 cohort (p = 0.015), M1b (p = 0.018), and M1c subgroups (p = 0.004), but not in M1a (p = 0.226). Nodal status showed no significant association with OS in any subgroup (M1a: p = 0.252; M1b: p = 0.762; M1c: p = 0.616). On multivariable Cox analysis, Gleason score ≥ 8 (HR = 2.65, 95%CI 1.21-5.79, p = 0.014), T4 stage (HR = 3.04, 95%CI 1.17-7.90, p = 0.023), and M1c substage (HR = 6.27, 95%CI 1.61-24.39, p = 0.008) emerged as independent predictors of poor survival.

[CONCLUSION] Our study suggests that nodal staging may have limited biological rationale in PCa when synchronous distant metastases exist.