Prediction of Contralateral Lymph Node Involvement during Extended Pelvic Lymph Node Dissection for Clinically Unilateral Prostate Cancer.

[BACKGROUND] Extended pelvic lymph node dissection (ePLND) plays a critical role in the accurate staging of prostate cancer; however, it is associated with increased perioperative morbidity. Refinement of the indications for ePLND through the identification of predictive factors for contralateral lymph node involvement (LNI) may contribute to minimizing overtreatment and associated complications.

[PATIENTS AND METHODS] In this retrospective study, we analyzed a cohort of 223 patients with clinically unilateral prostate cancer who underwent robot-assisted radical prostatectomy combined with bilateral ePLND. Tumor laterality was defined by biopsy and magnetic resonance imaging (MRI) findings. Associations between preoperative clinical factors and contralateral LNI were assessed using statistical tests.

[RESULTS] Contralateral LNI was significantly associated with PSA ≥10 ng/mL (6.3% vs. 0.7%; p = 0.047) and ≥66% positive biopsy cores in the ipsilateral lobe (8.0% vs. 0%; p = 0.0037). A risk classification model combining these two factors identified a high-risk group with 13.2% incidence of contralateral LNI, compared with 0.5% in the low-risk group (p = 0.0003).

[CONCLUSIONS] PSA level at diagnosis and the proportion of positive biopsy cores in the ipsilateral lobe are useful predictors of contralateral LNI in clinically unilateral prostate cancer. A preoperative risk model incorporating these variables may support a tailored approach to ePLND, minimizing surgical burden without compromising diagnostic accuracy.