Objective: The aim of this study was to investigate the frequency of secondary evaluation to detect prostate cancer that was primarily manifested as abnormal hypermetabolism detected by 18-fluoro-2-deoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT). We also evaluated the association of maximum standardized uptake values (SUVmax) on PET/CT with clinicopathologic results.
Materials and methods: We evaluated PET/CT reports from a total of 12,037 patients to find cases with abnormal prostate hypermetabolism. Patients with known prostate cancer or a recent prostate procedure were excluded. We analyzed the frequency of secondary evaluations such as digital rectal exams (DRE), levels of serum prostate-specific antigen (PSA), and/or biopsy to confirm prostate cancer. Biopsied patients were categorized into benign and cancer groups. Clinicopathologic characteristics were compared between the groups.
Results: Among 12,037 PET/CT images, 184 (1.5%) showed abnormal hypermetabolism in the prostate. Secondary evaluation was carried out in 120 patients. Biopsy was performed in 38 patients and prostate cancer was confirmed in 23 patients. The median serum PSA level was 3.2 and 49.7 ng/mL in the benign group and cancer group, respectively. The SUVmax was higher in the cancer group (5.7 ± 5.1) than in the benign group (4.8 ± 2.7), but the difference was not statistically significant (p = 0.37). In the cancer group, a high serum PSA level (≥ 20 ng/mL) was detected in 78.3% of the patients. The Gleason score was 7 in 34.7% and 8-10 in 56.5% of prostate cancer patients.
Conclusions: 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. Therefore, patients with hypermetabolism in the prostate should not be ignored and should be secondarily evaluated by DRE and PSA level.