Common Iliac Node-Positive Prostate Cancer Treated With Curative Radiation Therapy: N1 or M1a?

Area of Science:

• Urology
• Radiation Oncology
• Medical Oncology

Background:

• Common iliac (CI) lymph nodes are classified as M1a (oligometastatic) in prostate cancer staging.
• The distinction in outcomes between pelvic node-positive (cN1) and CI node-positive (CI-M1a) prostate cancer after curative treatment remains unclear.

Purpose of the Study:

• To compare the treatment outcomes of patients with cN1 versus CI-M1a prostate cancer.
• To evaluate the efficacy of radical whole pelvic radiation therapy (RT) combined with long-term androgen deprivation therapy (ADT) in these patient groups.

Main Methods:

• Retrospective analysis of node-positive prostate cancer patients (cN1 or CI-M1a) from a prospectively maintained database.
• Staging predominantly utilized Gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (Ga68-PSMA-PET/CT).
• All patients received long-term ADT and whole pelvic RT; restaging with Ga68-PSMA-PET/CT was performed at biochemical failure.

Main Results:

• Among 130 patients (87 cN1, 43 CI-M1a), biochemical failure-free survival (BFFS) at 5 years was similar (77.4% vs 70.4%, P=.43).
• Distant metastasis-free survival (86.9% vs 79.4%, P=.23) and overall survival (92.6% vs 90.1%, P=.80) were also comparable between the cN1 and CI-M1a groups.
• Outcomes for CI-M1a patients did not differ based on proximal versus distal CI nodal location.

Conclusions:

• Oligometastatic CI-M1a and cN1 prostate cancer patients demonstrate similar outcomes when treated with curative whole pelvic RT and long-term ADT.
• Prospective studies are recommended to further evaluate treatment strategies for these patient populations.