The Role of Untraceable Sentinel Lymph Nodes in Prostate Cancer Patients Undergoing Radical Prostatectomy and Pelvic...

Background/Objectives: The role of extended pelvic lymph node dissection (ePLND) in prostate cancer remains uncertain. Sentinel lymph node (sLN) mapping improves diagnostic precision, yet some patients have no detectable sentinel nodes ("untraceable" sLNs). This study evaluates whether untraceable sLNs predict the absence of lymph node invasion (LNI) and can guide surgical decision-making during radical prostatectomy (RP) with ePLND. Methods: Patients with intermediate- or high-risk prostate cancer and with no radiologically evident LNI were included in the study. A ^99mTc-nanocolloid was used as an sLN tracer. RP with sLN dissection and ePLND was performed <20 h after injection. Patients were categorized into two groups: Group 1, traceable sLNs and Group 2, untraceable sLNs (no radiological or intraoperative signal). Results: A total of 53 patients were included. LNI was present in 10 patients (18.9%). Group 1 had 41 patients (77.4%), and Group 2 had 12 patients (22.6%). None of the patients in Group 2 had LNI following ePLND, whereas 10 of 41 patients (24.4%) in Group 1 were node-positive (p = 0.016). Baseline clinical and pathological characteristics were comparable between groups. A total of 17/53 of men (32.1%) experienced biochemical recurrence, overall, with higher observed events in Group 1 (15/41, 36.6%) vs. Group 2 (2/12, 16.7%). However, this difference did not reach statistical significance (p = 0.2). Conclusions: A proportion of PCa patients have no radiologically or intraoperatively detectable sLNs, and none of the patients with untraceable sLNs exhibited LNI following ePLND. These findings suggest that untraceable sLNs may correlate with an extremely low probability of nodal invasion and could serve as a criterion for safely omitting ePLND in selected patients.