Cribriform pattern disease over-represented in pelvic lymph node metastases identified on 68GA PSMA-PET/CT

Objectives: To determine whether any specific histologic subtype of prostate cancer was preferentially represented in pelvic lymph node metastases identified on (68)GA-PSMA-PET/CT. Subjects and Methods: A consecutive series of 66 men with biochemical recurrent prostate cancer was evaluated with (68)GA-PSMA-PET/CT. Where disease was confined to pelvic lymph nodes, patients were offered salvage extended pelvic lymph node dissection. Twenty patients ultimately proceeded to extended bilateral template pelvic lymph node dissection. Lymph node positivity and the histologic subtype of apparent cancer were assessed, as was PSA response to this intervention. Results: Mean PSA at time of PSMA scanning for patients undergoing lymphadenectomy was 2.49 (n =20, range 0.21-12.0). In 16 of 20 patients, there was evidence of metastatic cribriform pattern prostate cancer in excised nodes (100% cribriform pattern in 11/16). Only four of 20 patients had no evidence of this histologic subtype of disease. PSA response was not related to the presence or proportional amount of cribriform pattern disease identified. Conclusions: Cribriform pattern adenocarcinoma appears to be the histologic subtype preferentially identified in pelvic lymph nodes on (68)GA-PSMA-PET/CT. The use of PSMA-PET may be particularly valuable in staging of primary or biochemically recurrent prostate cancer in patients with cribriform pattern disease detected on initial biopsy or radical prostatectomy. Further research is required to further confirm the observed association.