AUA 2022: When Node-Positive Prostate Cancer Should Be Considered A Systemic Disease? Assessing The Prognostic Role Of Preoperative 68Ga-PSMA PET/CT Results In Patients With Lymph Node Invasion At Final Pathology

( In a moderated poster presentation at the 2022 American Urologic Association Annual Meeting held in New Orleans and virtually, Dr. Robesti discussed the prognostic value of pre-operative 68-Ga prostate-specific membrane antigen (PSMA) PET among patients who are found to have lymph node invasion at the time of surgery. This work is premised on the idea that 68-Ga PSMA PET may identify nodal involvement preoperatively. Early identification of those with nodal involvement may be important to identify patients for early multi-modal treatment intensification.

To assess this, the authors identified 92 patients who underwent pre-operative 68Ga-PSMA PET/CT prior RP and extended lymph node dissection (LND) between 2019 and 2021 at two centers. They assessed the outcome of PSA persistence, defined as first PSA value after surgery ≥0.1 ng/ml. Further, they examined rates of true and false positive of PSMA PET/CT in detecting positive nodes at final pathology. Logistic regression models were used to assess the association between the preoperative PSMA PET/CT result and nodal status at final pathology on the risk of PSA persistence.

Pre-operatively, at the time of PSMA-PET/CT, the median PSA was 9 ng/ml (IQR: 5-16 ng/ml). Overall, 30 (33%) patients had a positive preoperative PSMA-PET/CT. Among these 30 patients, 19 had evidence of nodal disease on pathology. Conversely, 13 of the patients had a negative scan but positive nodes at pathology.

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Overall, 30 patients (33%) had PSA persistence. Rates of PSA persistence varied based on both pre-operative PSMA-PET/CT results and surgical pathology. Among men with negative PSMA PET and negative nodes at pathology, 8 (17%) had PSA persistence. Among patients with positive nodes at pathology, 5 out of 13 (38%) with negative PSMA PET and 12 of the 19 patients (63%) with positive scan had PSA persistence (p=0.01).

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Based on logistic regression models, men with positive nodes but negative PET PSMA (OR 2.81, p=0.15) and those with positive PSMA-PET but negative pathologic nodes (OR 2.70, p=0.20) had no statistically significantly higher risk of PSA persistence compared to these with negative scan and negative nodes. On the contrary, patients with positive scan and positive nodes at final pathology had a substantially higher risk of PSA persistence after surgery (OR 3.93, p=0.036).

Thus, the authors conclude that both preoperative 68Ga-PSMA PET/CT and surgical pathology have important prognostic implications for patients treated with RP and LND.

Presented by: Daniele Robesti, MD, Vita-Salute San Raffaele University

Written by: Christopher J.D. Wallis, University of Toronto, Twitter: @WallisCJD during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.

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