PSMA PET/CT cannot replace mpMRI for diagnosis of prostate cancer

18F-DCFPyL PSMA PET/CT imaging did not demonstrate better accuracy than multiparametric MRI in diagnosing prostate cancer in a phase 3 trial.

Phase-3 trial supports mpMRI as the standard option for detecting prostate cancer1

“Diagnosing prostate cancer with mpMRI remains imperfect,” stated Prof. Lih-Ming Wong (University of Melbourne, Australia), explaining the rationale of a phase 3 trial that compared PSMA-PET/CT to mpMRI, hypothesising that the first would be superior to the latter. A total of 235 participants with elevated PSA levels (>3.0, or >2.0 in case of positive family history), an abnormal digital rectal exam (DRE), and a low free/total PSA ratio (<25%) underwent both mpMRI and 18F-DCFPyL PSMA PET with chest/abdomen/pelvis CT to assess the diagnostic accuracy of both options. Participants with positive or equivocal findings were scheduled to undergo a biopsy to verify the results.

mpMRI displayed a better diagnostic accuracy for detecting prostate cancer than PSMA-PET/CT, as indicated by AUROC values (0.77 vs 0.62; P=0.0131). The corresponding sensitivity, specificity, and negative predictive values were 77.2%, 75.9%, and 61.2% for mpMRI and 68.4%, 55.6%, and 45.5% for PSMA-PET/CT. Prof. Wong added that clinically significant cancers were missed with both imaging techniques.

Although mpMRI outperformed PSMA-PET/CT in this trial, Prof. Wong argued that there may be a role for PSMA-PET/CT in the future. “PSMA-PET/CT needs finetuning. For example, we will not only be using SUVmax in the future, as was the case in this trial. Also, PSMA-PET/CT may be applied in patients with contraindications to MRI or in patients with equivocal MRI results who are reluctant to undergo biopsy.

1. Wong L-M, et al. Phase III study comparing diagnostic accuracy of mpMRI prostate to 18F-DCFPyL PSMA PET/CT. Game-changing session 6, EAU 2022, 01–04 July.