(68)Ga-PSMA PET/CT for restaging recurrent prostate cancer: which factors are associated with PET/CT detection rate?

• Published in: European journal of nuclear medicine and molecular imaging Vol. 42; no. 8; pp. 1284 - 1294
• Main Authors: Ceci, Francesco, Uprimny, Christian, Nilica, Bernhard, Geraldo, Llanos, Kendler, Dorota, Kroiss, Alexander, Bektic, Jasmin, Horninger, Wolfgang, Lukas, Peter, Decristoforo, Clemens, Castellucci, Paolo, Fanti, Stefano, Virgolini, Irene J
• Format: Journal Article
• Language: English
• Published: Germany 01.07.2015
• Subjects: Adult; Aged; Aged, 80 and over; Edetic Acid - analogs & derivatives; Humans; Male; Middle Aged; Multimodal Imaging; Neoplasm Recurrence, Local - diagnostic imaging; Neoplasm Recurrence, Local - pathology; Neoplasm Staging; Oligopeptides; Positron-Emission Tomography; Prostatic Neoplasms - diagnostic imaging; Prostatic Neoplasms - pathology; Radiopharmaceuticals; Sensitivity and Specificity; Tomography, X-Ray Computed
• ISSN: 1619-7089
• DOI: 10.1007/s00259-015-3078-6

To assess the association between PSA levels, PSA kinetics and other factors and a pathological (68)Ga-PSMA PET/CT scan in patients with recurrent prostate cancer (rPCa) with biochemical relapse (BR) after radical therapy. Seventy consecutive rPCA patients referred for (68)Ga-PSMA PET/CT, matching all the following criteria, were retrospectively evaluated: (a) previous radical prostatectomy or primary radiotherapy with curative intent; (b) BR or persisting high PSA levels after primary treatment; and (c) complete clinical and imaging information. The mean ± SD PSA level was 3.5 ± 5.3 ng/mL (median 1.7, range 0.2 - 32.2 ng/mL), the mean ± SD PSA doubling time (PSAdt) was 6.5 ± 5.5 months (median 5.5, range 1.3 - 31.6 months), and the mean ± SD PSA velocity was 7.9 ± 20.5 (median 2.1, range 0.2 - 147.5 ng/mL/year). Statistical analysis was performed to assess which factors were associated with the detection of rPCa on (68)Ga-PSMA PET/CT. (68)Ga-PSMA PET/CT was positive in 52 of 70 patients (74.2%). In 30 patients (42.8%) lesions limited to the pelvis were detected. Distant lesions were observed in 8 of patients (11.4%). Local plus systemic lesions were detected in 14 patients (20%). PSA level (p = 0.017) and PSAdt (p = 0.0001) were significantly different between PET-positive patients (higher PSA level, shorter PSAdt) and PET-negative patients (lower PSA, longer PSAdt). ROC analysis showed that PSAdt 6.5 months and PSA 0.83 ng/mL were optimal cut-off values. In multivariate analysis PSAdt was associated with (68)Ga-PSMA PET/CT positivity. (68)Ga-PSMA PET/CT was positive in 17 of 20 patients (85%) with PSA <2 ng/mL and PSAdt <6.5 months, and in 3 of 16 patients (18.7%) with PSA <2 ng/mL and PSAdt ≥6.5 months. The great potential of (68)Ga-PSMA PET/CT in patients with rPCa and BR was confirmed. PSA and PSAdt were valuable predictors of pathological (68)Ga-PSMA PET/CT findings.