Treatment procedures

For 6–9 months before RP, all patients with high-risk PC who have elected to undergo RP received neoadjuvant ADT (luteinizing hormone–releasing hormone agonist or gonadotropin-releasing hormone antagonist) plus low-dose EMP (280 mg/day) in our institution, as previously described^10,11,24. With the approval of RARP in Japan in January 2012, RARP has been performed in most cases; in earlier cases, RRP was performed. Considering that the rate of positive lymph nodes was approximately 1% in patients with high-risk PC treated with neoadjuvant ADT plus low-dose EMP followed by RP at our institution²⁴, we stopped PLND in October 2015. Thus, we categorized patients into two groups according to treatment strategy shift: limited-PLND group (patients with high-risk PC who received limited PLND; between January 2010 and October 2015) and non-PLND group (patients who did not receive limited PLND; after November 2015). The limited-PLND group underwent the same lymphadenectomy method, including removal of the bilateral obturator nodes. Surgical complications were evaluated using the Clavien–Dindo classification³⁹. The risk of lymph node invasion was retrospectively calculated using the Briganti nomogram³¹.