Persistent lymph node uptake on [18 F]-FDG PET-CT after neoadjuvant chemotherapy: a major predictive factor of...

Locoregional lymph node involvement significantly worsens the prognosis of muscle invasive urothelial carcinoma of the bladder. Depending on disease burden, systemic chemotherapy is administered preoperatively either as a neoadjuvant treatment for localized cases, or as induction systemic therapy, when radiologic evidence suggests locoregional nodal involvement. Current lymph node assessment relies on CT imaging, but the added value of [18 F]-FDG PET-CT remains unclear. The objective of this study was to evaluate the prognostic value of lymph node assessment using [18 F]-FDG PET-CT performed before and after preoperative chemotherapy.

We conducted a retrospective single-center study on consecutive patients who received preoperative chemotherapy (neoadjuvant or induction systemic therapy) followed by radical cystectomy for MIBC between 2017 and 2025. Patients who underwent both pre and post-chemotherapy [18 F]-FDG PET-CT were included and categorized into three groups based on nodal metabolic uptake, before and after chemotherapy: (-)/(-), (+)/(-), and (+)/(+). The primary objective was to assess disease-free survival (DFS) according to nodal [18 F]-FDG uptake before and after chemotherapy.

Forty-one patients were included, with a median age of 66 years (range 36-78), Preoperative chemotherapy consisted of ddMVAC in 65.9% of cases, with a median of 4 cycles (range 1-6). Seven patients (17.1%) were ypN1 and three (7.3%) were ypN2. At 7 months, all patients with persistent positive uptake experienced disease progression. DFS was significantly lower in the (+)/(+) group (log-rank p < 0.001), followed by (+)/(-), and (-)/(-) groups. In multivariate Cox analysis, persistent lymph node uptake on [18 F]-FDG PET-CT ((+)/(+)) was an independent prognostic factor of worse DFS (HR 6.24; 95% CI 1.64-23.7; p = 0.007), regardless of final T stage and nodal invasion.

Persistent lymph node [18 F]-FDG uptake on PET-CT after chemotherapy is an independent adverse prognostic factor for disease-free survival.