BALANCE is a multicenter, prospective, randomized controlled trial enrolling men with unilateral high-risk localized prostate cancer identified by prostate biopsy, multiparametric MRI, and PSMA PET imaging. Eligible patients scheduled for robot-assisted radical prostatectomy will be randomized in a 1:1 ratio to undergo either unilateral extended pelvic lymph node dissection or bilateral extended pelvic lymph node dissection.

Pelvic lymph node dissection is commonly performed in high-risk prostate cancer for staging purposes, but its therapeutic benefit remains uncertain and the procedure may increase operative time, costs, and postoperative morbidity. Modern imaging techniques may improve the identification of patients with predominantly unilateral disease and support a more selective surgical approach.

The co-primary objectives are to compare 3-year biochemical recurrence-free survival and early postoperative PSA persistence between the two surgical strategies. Secondary objectives include comparison of perioperative complications, operative time, blood loss, length of hospital stay, quality of life, long-term oncologic outcomes, and costs.

This study is designed to determine whether unilateral extended pelvic lymph node dissection can reduce surgical morbidity while preserving oncologic outcomes in appropriately selected patients with high-risk prostate cancer.

Inclusion Criteria:

• Male patients aged 18 years or older
• Histologically confirmed unilateral high-risk localized prostate cancer, defined by at least one of the following: ISUP Grade Group 4 or 5; suspicion of at least cT3a disease on multiparametric MRI and/or PSMA PET; or PSA greater than or equal to 20 ng/mL with a unilateral index lesion
• Unilateral features of the index lesion defined by biopsy, multiparametric MRI, and PSMA PET
• No PSMA PET-positive pelvic lymph nodes contralateral to the dominant side of the prostate cancer
• No significant contralateral PSMA uptake on the non-dominant side, defined as lesions with PRIMARY score 3 to 5
• No contralateral index lesion on multiparametric MRI subsequently confirmed by prostate biopsy
• No high-risk histology on the side contralateral to the dominant lesion, including ISUP Grade Group greater than 3 or unconventional prostate cancer histology
• No frank extracapsular invasion or seminal vesicle invasion on the contralateral side
• Up to two positive systematic cores with unfavorable intermediate-risk disease or up to four with favorable intermediate-risk disease are allowed on the contralateral side
• A maximum of two pelvic PSMA-positive lymph nodes allowed on the dominant side
• Clinically localized disease, defined as less than cT4 on multiparametric MRI and no distant metastases, including no retroperitoneal lymph nodes on PSMA PET
• Life expectancy greater than 10 years according to physician judgment
• Scheduled for robot-assisted radical prostatectomy and fit for surgery
• Written informed consent provided

Exclusion Criteria:

• Any prostate cancer treatment prior to prostatectomy, including androgen deprivation therapy, neoadjuvant chemotherapy, radiotherapy, or focal ablative therapy
• Prior active treatment for prostate cancer
• Contralateral ISUP Grade Group 4 to 5 prostate cancer
• Contralateral ISUP Grade Group 2 in more than 4 positive cores or ISUP Grade Group 3 in more than 2 positive cores
• Contralateral cT3 disease on multiparametric MRI
• N1 or M1 disease on PSMA PET or multiparametric MRI, except for up to two positive pelvic lymph nodes on the dominant side
• No systematic prostate biopsies performed, with a minimum of 10 cores, and targeted biopsies when a target lesion is present
• Other active malignancy
• Contraindication to multiparametric MRI and/or PSMA PET
• Inability to provide written informed consent
• Age younger than 18 years
• ASA score greater than 3
• Any contraindication to pelvic lymph node dissection
• Severe psychiatric disease
• Inadequate hematologic and/or coagulation function
• Active infection
• Any other serious medical, psychiatric, psychological, familial, or geographic condition that, in the judgment of the investigator, may interfere with staging, treatment, follow-up, compliance, or increase treatment-related risk
• Patients with prior malignancy treated with curative intent are eligible only with mandatory approval by the local multidisciplinary tumor board

No individual participant data sharing plan is currently available.