Prostate cancer is the second most common cancer in American men, with 1 in 8 being diagnosed with this cancer type during their lifetime.1 In 2021, it is estimated that >248,500 men in the United States will be diagnosed with prostate cancer.1 Most cases are diagnosed via screening tests such as digital rectal examination and/or prostate-specific antigen (PSA) test.2 Confirmation and grading are typically performed with biopsy and imaging tests.2 Prostate-specific membrane antigen (PSMA) is usually found in large amounts in prostate cancer cells and has been associated with higher PSA and International Society of Urological Pathology grade levels and a worse overall survival.3 Similar to other radiotracers used in conventional imaging, radiotracers that attach to PSMA have been developed to be used during positron emission tomography (PET) scans to improve diagnostic accuracy and further study prostate cancer.3
Farolfi and colleagues recently performed a literature review to evaluate the current and emerging clinical applications of PSMA-PET diagnostic imaging for prostate cancer. This review was performed to highlight the established and in-development diagnostic application of PSMA compounds during the diagnosing and monitoring of prostate cancer. Farolfi found that the data suggest that PSMA-based radioligands have high diagnostic value in imaging studies for prostate cancer, including yielding valuable prognostic information, especially in patients with Gleason 3+4 who are potentially suitable for focal therapy or active surveillance.3 In primary prostate cancer, PSMA-PET was found to be superior to cross-sectional imaging in detecting distant metastases along with spread to lymph nodes and bone. Regarding lymph node and bone spread, PSMA-PET has a high specificity and positive predictive values, but less than optimal sensitivity.3
When PSMA-PET was combined with multiparametric magnetic resonance imaging (mpMRI) PSMA-PET, intraprostatic cancer detection and intraprostatic gross tumor volume accuracy were superior to mpMRI alone. PSMA-PET also leads to changes in clinical management, which leads to more focal therapies over systemic therapies or no treatment.3 In addition, it can aid in targeted biopsy of the prostate when combined with mpMRI, yielding negative or inconclusive results in a patient with high clinical suspicion of prostate cancer.
In recurrence of prostate cancer, high detection rates were observed in PSMA-PET when compared with other imaging techniques. In those patients who have oligometastatic disease after radical surgery, the phase 2 Observation vs Stereotactic Ablative Radiation for Oligometastatic Prostate Cancer (ORIOLE) study found that PSMA-PET may provide a benefit in detection and guiding therapy and improvement in progression-free survival and distant metastases-free survival advantage.3 The study authors also found that PSMA-PET is a reliable whole-body imaging tool when combined with second-line therapy for patients with castration-resistant prostate cancer. It can also be a useful imaging tool for assessing a patient’s eligibility for radioligand therapy.
At the conclusion of the literature review, the authors discussed several criteria for standardized methods to read and interpret images that have been proposed, including Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) criteria, PSMA Reporting and Data Systems (RADS), and E-PSMA.
References
- American Cancer Society. Key statistics for prostate cancer. Updated January 12, 2021. www.cancer.org/cancer/prostate-cancer/about/key-statistics.html. Accessed September 20, 2021.
- American Cancer Society. Tests to diagnose and stage prostate cancer. Updated June 10, 2021. www.cancer.org/cancer/prostate-cancer/detection-diagnosis-staging/how-diagnosed.html. Accessed September 20, 2021.
- Farolfi A, Calderoni L, Mattana F, et al. Current and emerging clinical applications of PSMA PET diagnostic imaging for prostate cancer. J Nucl Med. 2021;62:596-604.
