EAU 2021: A Prospective Study Assessing the Post-Prostatectomy Detection Rate of a Presumed Local Failure at mpMRI with 18F-Choline, 64Cu-Cl2 or 64Cu-PSMA PET/CT

(UroToday.com) The detection of recurrence and salvage treatment options after primary treatment for prostate cancer session at the European Association of Urology 2021 annual meeting included a presentation by Dr. Maria Ferriero discussing a prospective study assessing post-prostatectomy detection rate of presumed local failure at mpMRI with 18F-choline, 64Cu-Cl2 or 64Cu-PSMA PET/CT. 64Cu-Cl2 or 64Cu-PSMA PET/CT are novel tracers in the assessment of patients that may be candidates for salvage radiotherapy with a presumed local recurrence at mpMRI after radical prostatectomy.

This prospective study was conducted at a single institution (I.R.C.C.S. Regina Elena National Cancer Institute) between August 2017 and June 2020. The eligibility criteria for this trial were as follows:

  • Undetectable PSA after radical prostatectomy
  • Subsequent biochemical recurrence (two consecutive PSA rises to 0.2 ng/ml or greater)
  • A presumed local failure at mpMRI
  • No distant metastases at 18F-Fluorocholine PET/CT
  • No previous history of androgen deprivation therapy

Accrued patients were offered both 64Cu-Cl2 PET/CT and 64Cu-PSMA PET/CT before salvage radiotherapy. While blinded to mpMRI findings, two observers jointly reviewed PET/CTs and contoured any positive lesion. All diagnostic images were co-registered with the planning CT, and PET/CT lesions whose centroid was within 1 cm from one of the lesions detected at mpMRI were considered true positive. Data were analyzed in terms of detection rates and compared with the McNemar test for correlated proportions. Confidence Intervals were computed with the Wilson score method without continuity correction. Statistical significance was claimed for p values <0.05.

There were 62 patients with 72 nodules at mpMRI accrued to this study. Four patients refused 64Cu-PSMA PET/CT. Compared to mpMRI (detection rates = 100%, 95%CI: 94.9-100%), detection rates were 31.0% (95%CI: 21.4-42.5%), 47.2% (95%CI: 36.1-58.6%) and 54.4% (95%CI: 42.7-65.7%) for 18F-Fluorocholine PET/CT, 64Cu-Cl2 PET/CT and 64Cu-PSMA PET/CT, respectively. Both 64Cu-Cl2 PET/CT and 64Cu-PSMA PET/CT showed a higher rate of local disease detection than 18F-Fluorocholine PET/CT (p<0.001 for both), but all PET/CT scans performed significantly worse than mpMRI (p<0.001 for all):

 

Ferriero_EAU21_figure1 

 

Stratification by median values and subgroup analysis showed PET/CT detection rates to be variably correlated to selected covariates (serum PSA level at failure, disease volume at mpMRI, and time elapsed from surgery to failure). However, even when selecting the more favorable performing subgroups (i.e those with serum PSA >0.5 ng/ml), detection rates of all PET/CT tracers were consistently lower (p<0.001) than the ones achieved by mpMRI in any subgroup.

Dr. Ferriero concluded that although the two novel radiotracers 64Cu-Cl2 or 64Cu-PSMA have shown significantly superior detection rates than 18F-choline, they both missed a significant number of presumed local failures detected at mpMRI. As such, multiparametric MRI remains the preferred imaging modality to localize a local failure after radical prostatectomy.

Presented By: Maria C. Ferriero, I.R.C.C.S. Regina Elena National Cancer Institute, Dept. of Urology, Rome, Italy

Coauthors: Sanguineti G.1, Giannarelli D.2, Faiella A.1, Bottero M.1, Farneti A.1, Bertini L.3, Rea S.2, Landoni V.4, Sciuto R.2

1I.R.C.C.S. Regina Elena National Cancer Institute, Dept. of Radiation Oncology, Rome, Italy, 2I.R.C.C.S. Regina Elena National Cancer Institute, Dept. of Nuclear Medicine, Rome, Italy, 3I.R.C.C.S. Regina Elena National Cancer Institute, Dept. of Radiology, Rome, Italy, 4I.R.C.C.S. Regina Elena National Cancer Institute, Dept .of Physics, Rome, Italy, 5I.R.C.C.S. Regina Elena National Cancer Institute, Dept. of Urology, Rome, Italy

Written By: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.

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