BERKELEY, CA (UroToday.com) - 18-fluoro-2-deoxyglucose (FDG) positron emission tomography–computed tomography (PET/CT) scanning is commonly used for staging and restaging of various malignancies. However, in urology, and especially in the detection of prostate cancer, FDG PET/CT has several potential problems. These include interruption of results by physiological urinary excretion of FDG, low sensitivity due to low metabolic activity for prostate cancer, and accumulation of FDG during inflammation. When FDG PET/CT detects incidental focal uptake in the prostate, it is questionable whether this result is indicative of cancer or not. In this article, we evaluated how many patients had focal hypermetabolism in F-18 FDG PET/CT and how many of them underwent secondary evaluation.
We reviewed a total of 12 037 PET/CT reports of patients without prostate disease history. We found 184 cases (1.5% of total PET/CT) with prostate hypermetabolism, and 120 of them underwent further evaluation such as digital rectal exams (DRE) and serum prostate-specific antigen (PSA) testing in our institution. Prostate biopsy was performed in 38 patients who had abnormal nodular lesions on DRE or a serum-PSA level exceeding 3.0 ng/mL. Finally, 23 patients were diagnosed as prostate cancer.
Hypermetabolism in the prostate was incidentally detected in 1.5 % of patients, and only 65.2 % of these patients underwent further evaluation (DRE and/or serum PSA levels). Among cases of incidentally detected hypermetabolism in the prostate, patients with abnormal findings (DRE and/or PSA levels) showed high positivity by biopsy, and more than two-thirds of the positive biopsies showed significant prostate cancer.
Routine prostate biopsy is usually not recommended due to poor performance of FDG PET/CT in the primary diagnosis of prostate cancer, and hypermetabolism in the prostate detected by FDG PET/CT scans is sometimes ignored; 64 patients (34.8%) did not have DRE performed or had serum PSA testing without further evaluation. Clinicians might tend to think that the focal uptake in prostate could be physiologic or less important, due to low sensitivity of FDG PET for prostate cancer, and hypermetabolism in the prostate upon FDG PET/CT scan is sometimes ignored. Therefore, the result of our study might not reflect the exact incidence of prostate cancer in hypermetabolic lesions that took up FDG.
Despite of the limitations of our study, among incidentally detected hypermetabolism in the prostate, patients with abnormal findings (DRE and/or PSA) showed high positivity of biopsy and more than two-thirds of cancers showed significant prostate cancer. Our result shows that incidental focal uptake in the prostate gland should not be ignored and should be secondarily evaluated by a urologist.
Written by:
Seung Il Jung, MD, PhD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Associate Professor
Chonnam National University Hwasun Hospital
322 Seoyang-ro, Hwasun-eup, Hawsun-gun, Jeollanam-do,
519-763,
Republic of Korea
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