The factors determining positive detection rate of 68Ga PSMA PET/CT in patients with early biochemical recurrence prostate cancer

Abstract

To examine predictive markers for high detection rates of 68Ga PSMA-PET/CT in biochemical recurrence (BR) prostate cancer (PCa) patients with low PSA levels. This trial was planned as a retrospective single center study. Patients with BR prostat cancer were included. PSA levels of all patients were lower 2 μg/l. Totally thirty-two men patients with BR PCa were included in this study. 18 (56.3%) patients underwent radical prostatectomy and 14 (43.7%) patients curative intense radiotherapy. The number of patients received adjuvant maximal androgen blokage (MAB) treatment was 15 (46.9%). Median PSA levels was calculated 1.03 μg/l 17 (53.1%) of patients had <1 μg/l PSA levels and 7 (21.8%) of patients <0.5 μg/l. The patients number was 16 in unfavorable intermediate risk group (50.0%), 12 (37.5%) in high group and 4 (12.5%) in very high group. The median PSA doubling time was 6.2 months. The number of patients received adjuvant MAB treatment was 15 and in 14 (93.3%) of patients were found positive lesion in 68Ga PSMA-PET/CT. The number of patients with at least one lesion detected on 68Ga PSMA-PET/CT was 19 (59.4%). In univariate analysis to detect the factors affecting 68Ga PSMA-PET/CT positivity, there was only the presence of adjuvant MAB treatment as statistically significant importance (p < 0.001) and in multivariate analysis, the presence of adjuvant MAB treatment was found to be as statistically significant factor in terms of affecting 68Ga PSMA-PET/CT positivity (p = 0.003). The cut-off value was calculated as 1.12 μg/l in patients with no adjuvant MAB treatment (sensitivity 80% and specificity 83.3%). Clinicians may perform 68Ga PSMA PET/CT in low PSA levels to detect lesions in biochemical recurrent prostate cancer patients who had received MAB treatment and in patients with higher PSA levels who had no received MAB treatment.