Survey by the French Medicine Agency (ANSM) of the imaging protocol, detection rate, and safety of 68Ga-PSMA-11 PET/CT in the biochemical recurrence of prostate cancer in case of negative or equivocal 18F-fluorocholine PET/CT: 1084 examinations.

Despite growing evidence of a superior diagnostic performance of 68Ga-PSMA-11 over 18F-fluorocholine (FCH) PET/CT, the number of PET/CT centres able to label on site with gallium-68 is still currently limited. Therefore, patients with biochemical recurrence (BCR) of prostate cancer frequently undergo FCH as the 1st-line PET/CT. Actually, the positivity rate (PR) of a second-line PSMA-11 PET/CT in case of negative FCH PET/CT has only been reported in few short series, in a total of 185 patients. Our aims were to check (1) whether the excellent PR reported with PSMA-11 is also obtained in BCR patients whose recent FCH PET/CT was negative or equivocal; (2) in which biochemical and clinical context a high PSMA-11 PET/CT PR may be expected in those patients, in particular revealing an oligometastatic pattern; (3) whether among the various imaging protocols for PSMA-11 PET/CT used in France, one yields a significantly highest PR; (4) the tolerance of PSMA-11.

Six centres performed 68Ga-PSMA-11 PET/CTs during the first 3 years of its use in France. Prior to each PET/CT, the patient's data were submitted prospectively for authorisation to ANSM, the French Medicine Agency. The on-site readings of 1084 PSMA-11 PET/CTs in BCR patients whose recent FCH PET/CTs resulted negative or equivocal were pooled and analysed.

(1) The overall PR was 68%; for a median serum PSA level (sPSA) of 1.7 ng/mL, an oligometastatic pattern (1-3 foci) was observed in 31% of the cases overall; (2) PR was significantly related to sPSA (from 41% if < 0.2 ng/mL to 81% if ≥ 2 ng/mL), to patients' age, to initial therapy (64% if prostatectomy vs. 85% without prostatectomy due to frequent foci in the prostate fossa), to whether FCH PET/CT was negative or equivocal (PR = 62% vs. 82%), and to previous BCR (PR = 63% for 1st BCR vs. 72% in case of previous BCR); (3) no significant difference in PR was found according to the imaging protocol: injected activity, administration of a contrast agent and/or of furosemide, dose length product, one single or multiple time points of image acquisition; (4) no adverse event was reported after PSMA-11 injection, even associated with a contrast agent and/or furosemide.

Compared with the performance of PSMA-11 PET/CT in BCR reported independently of FCH PET/CT in 6 large published series (n > 200), the selection based on FCH PET/CT resulted in no difference of PSMA-11 PR for sPSA < 1 ng/mL but in a slightly lower PR for sPSA ≥ 1 ng/mL, probably because FCH performs rather well at this sPSA and very occult BCR was over-represented in our cohort. An oligometastatic pattern paving the way to targeted therapy was observed in one fourth to one third of the cases, according to the clinico-biochemical context of the BCR. Systematic dual or triple acquisition time points or administration of a contrast agent and/or furosemide did not bring a significant added value for PSMA-11 PET/CT positivity and should be decided on individual bases.

European journal of nuclear medicine and molecular imaging. 2021 Jan 08 [Epub ahead of print]

Yanna-Marina Chevalme, Lotfi Boudali, Mathieu Gauthé, Caroline Rousseau, Andrea Skanjeti, Charles Merlin, Philippe Robin, Anne-Laure Giraudet, Marc Janier, Jean-Noël Talbot

Direction des médicaments en oncologie, hématologie, transplantation, néphrologie, thérapie cellulaire, produits sanguins, et radiopharmaceutiques, Agence Nationale de Sécurité du Médicament et des produits de santé (ANSM), 143 Bd Anatole, F93200, St Denis, France. ., Direction des médicaments en oncologie, hématologie, transplantation, néphrologie, thérapie cellulaire, produits sanguins, et radiopharmaceutiques, Agence Nationale de Sécurité du Médicament et des produits de santé (ANSM), 143 Bd Anatole, F93200, St Denis, France., Service de médecine nucléaire, Hôpital Tenon, AP-HP Sorbonne Université, Paris, France., Nuclear Medicine Unit, ICO René Gauducheau, CNRS, Inserm, CRCINA, Nantes University, F-44000, Nantes, France., Nuclear Medicine Department, Hospices Civils de Lyon, EA 3738, Université Claude Bernard Lyon 1, Lyon, France., Nuclear Medicine Department, Cancer Center Jean PERRIN, Clermont-Ferrand, France., Service de Médecine Nucléaire, EA 3878 (GETBO), Centre Hospitalier Régional et Universitaire de Brest, Université de Bretagne Occidentale, Brest, France., Nuclear Medicine Department LUMEN, Léon Bérard Cancer Center, Lyon, France.