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Multicenter International Prospective Trial on Gallium-68 PSMA PET/CT Imaging Confirms Accuracy in Detecting Prostate Cancer Recurrence

Web Exclusives — October 19, 2021

One of the most common cancers in men is prostate cancer.1 There are different approaches to prostate cancer treatment, including external beam therapy, brachytherapy, cryotherapy, or radical prostatectomy.1 Despite treatment, up to 40% of patients will experience a biochemical recurrence (BCR) at some point.1 BCR of prostate cancer is defined as the posttreatment detection of serum prostate-specific antigen (PSA) levels.1 The specific PSA level to determine if BCR has occurred depends on the primary treatment the patient received.1 If a radical prostatectomy was performed on the patient, serum PSA levels should be low or undetectable.1 If PSA levels are found to be elevated, investigation to find lesions responsible for this PSA level rise is necessary, but can be a clinical challenge with standard imaging.2 Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) radiotracer has been found to provide better accuracy at lesion detection than standard imaging.2

Dr Juliano Cerci and Dr Stefano Fanti presented the results of a phase 3, prospective, multicenter study on the use of gallium-68 PSMA PET/computed tomography (CT) imaging in early-relapsed prostate cancer at the 2021 American Society of Clinical Oncology annual meeting. The diagnostic performance and clinical impact of PSMA-PET/CT in evaluating BCR in prostate cancer was this study’s aim. There were 1198 patients with prostate cancer who were recruited from 15 countries for the study. They each had primary treatment with subsequent rising PSA levels. Of these patients, 1004 had final data available.2 When gallium-68 PSMA PET/CT scans were run, 654 final participants were positive. Based on the PSMA results, 56.8% of the patients had their treatment modified. Lesions were identified in the prostate/prostate bed in 13.7% of cases, in the pelvic lymph nodes in 20.5% of cases, and metastatic disease was found in 27% of patients.2 When Gleason scores were evaluated, a PSMA-PET/CT positivity correlation was found. The detection rate was 60.5% for patients with a Gleason score of 7; 66.3% in patients with a Gleason score of 8; 77.8% for patients with a Gleason score of 9; and 86.7% for patients with a Gleason score of 10.2

PSA levels also had a correlation with lesions identified with PSMA-PET/CT. For patients with a PSA <0.2, the detection rate was 51.2%; for PSA 0.2-0.5, the detection rate was 44.7%; for PSA 0.5-1.0, the detection rate was 53.4%; for PSA ≥1 but <2, the detection rate was 67.2%; for PSA ≥2 but <4, the detection rate was 83%; and for PSA 4-10, the detection rate was 94.1%.2

References

  1. McCormick BZ, Mahmoud AM, Williams SB, Davis JW. Biochemical recurrence after radical prostatectomy: current status of its use as a treatment endpoint and early management strategies. Indian J Urol. 2019;35:6-17.
  2. Cerci JJ, Fanti S. Diagnostic performance of Gallium-68 prostate-specific membrane antigen (PSMA) PET/CT imaging in early-relapsed prostate cancer: phase 3, prospective, multicenter study (IAEA-PSMA study). J Clin Oncol. 2021;39(15_suppl):5078-5078.

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