Session Item

Common iliac (CI) nodes are staged as M1a for prostate cancer. It is unclear if outcomes of pelvic node-positive (N1) differ from CI node-positive (CI-M1a) cancer after curative treatment. Present study compares outcomes in these patients treated with radical radiotherapy and ADT

Patients with node-positive adenocarcinoma prostate were identified, either CI-M1a or N1, from a prospectively maintained database. Over 75% of these patients were staged with Ga68PSMA-PETCT at diagnosis. Patients received long-term ADT and moderately or extremely hypofractionated IGRT radiotherapy to the prostate and whole pelvis including CI region. At biochemical failure, restaging was with Ga68PSMA-PETCT. CI-M1a cohort was also studied by proximal or distal CI nodal location

Of the 129 patients analyzed, 87 had N1 and 42 had CI-M1a stage. The median duration of ADT before RT was 7 months. The majority (65%) had Gleason grade group IV or V while 75% had >T3 disease. After a median FU of 60 months, biochemical failure in the 2 groups was similar, N1, 21/87 (24.1%) and CI-M1a, 10/42 (23.8%), p=0.96. Distant metastases were seen in 23/31 (74.2%) in the whole cohort, being higher in the CI-M1a group [(N1: 14/21 (66.7%) and CI-M1a: 9/10 (90%), p=0.16]. Five-year biochemical failure-free survival (N1 71.6% and CI-M1a 76.8%, p=0.54) and overall survival (N1 91.0% and CI-M1a 96.6%, p=0.92) were similar in the two groups. Outcomes within CI-M1a were similar for proximal versus distal CI nodal location, 5-year BFFS 76.5% vs 58% (p=0.36).

The outcomes in CI-M1a and N1 are similar when treated with curative RT and ADT. Although categorized as metastatic, patients with CI-M1a should be offered curative treatment. These results need prospective validation