Nodal Tumor Occupancy Is an Unrecognized but Crucial Prognostic Factor for Postoperative Recurrence in Prostate Cancer Patients with Lymph Node Oligometastases

Abstract

Objectives: No well-defined guidelines are in place to manage pathologically node-positive (pN1) cases after definitive surgery for localized prostate cancer. We explored the prognostic value of the nodal tumor burden in positive nodes by offsetting the strong impact of the number of positive nodes.

Methods: Of 389 patients who underwent extended pelvic lymph node dissection (PLND) during robot-assisted radical prostatectomy, 50 (12.9%) patients with ≤ 3 positive nodes were enrolled, excluding those who were clinically node-positive or received neoadjuvant androgen deprivation therapy. Detailed investigations concerning the positive nodes with maximum cancer occupancy (MCO) and largest cancer nest (LCN) size were performed, and their associations with biochemical recurrence (BCR)-free survival were analyzed.

Results: After a median follow-up period of 27.5 months, 28 patients were diagnosed with BCR. International Society of Urological Pathology (ISUP) grade group > 3 at prostatectomy, MCO > 80%, and LCN > 2150μm were significant prognostic factors of BCR. Independent prognostic values were maintained in multivariate models with known factors analyzed separately for the above parameters. The BCR-free survival rate decreased with the increasing number of adverse factors, including surgical margins (model using MCO: not reached to the median with zero risk, 39.0 months with one risk, 15.0 months with two risks, and 1.5 months with three risks).

Conclusions: The tumor burden on the positive node provides independent prognostic value for biochemical recurrence and adds a rationale for selecting management options when PLND has been performed for therapeutic intent and diagnosed with ≤ 3 positive nodes.