Dr. Gandaglia began his presentation by noting that the role of PSMA PET/CT in the primary staging for patients with prostate cancer is still debatable. Metaanalyses have demonstrated that in studies where LN involvement prevalence ranged between 5 and 20%, the negative predictive value of PSMA PET/CT remained steadily above 90%. Although previous studies suggested a high NPV in intermediate risk patients, the variation of FN rate according to the prevalence of LN invasion based on pre-operative risk assessment has never been tested.
The aim of this study was to explore the variation of FN rates in a consecutive cohort of men receiving preoperative PSMA PET. The authors identified 90 patients evaluated with 68 Ga-PSMA PET/CT before RP and extended LN dissection between 2019 and 2021 at two referral centers. The main outcome was the FN rate. To test the correlation between the pre-operative LN risk and FN rate, the Briganti nomogram was utilized. The association between the pre-operative LN risk and FN rate was further assessed using logistic regression analyses and the Lowess function.
The baseline patient characteristics are displayed below. Median pre-operative LN involvement risk was 31% (IQR 17-52%). 30 patients had a positive PSMA PET/CT. The FN rate was 22%.
On a per patient basis: PSMA PET/CT showed:
- 59% sensitivity
- 81% specificity
- 78% NPV
- 63% PPV
On logistic regression analysis, a higher pre-operative LN risk, per the Briganti nomogram, was significantly associated with an increased risk of a positive PET/CT finding (HR 1.36, p=0.02). At Lowess analysis, the NPV progressively increased with higher LNI risk. Notably, FN rates remained equal or lower 10% in patients with a low risk of LNI (< 15%).
Dr. Gandaglia concluded as follows:
- The NPV of preoperative PSMA PET/CT is strongly correlated with the pre-operative LN risk.
- In patients with low LN risk with pre-operative nomograms and negative PSMA PET, the omission of LN dissection could be considered in the light of the very low rate of FN.
- This evidence reinforces the need to prospectively explore the diagnostic role of PSMA PET compared to LN dissection in patients with intermediate risk disease.
Presented by: Giorgio Gandaglia, MD, FEBU, Department of Urology, Vita-Salute San Raffaele University, Milan, Italy
Written by: Rashid Sayyid, MD, MSc – Urology Chief Resident, Augusta University/Medical College of Georgia, @rksayyid on Twitter during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.