Gleason score at diagnosis predicts the detection rate of ¹⁸F-choline PET/CT performed at biochemical recurrence of prostate cancer: experience with 1,000 patients

Abstract

Rationale: Gleason score (GS) is a well-established predictive risk factor for recurrence prostate cancer (PCa) after primary treatment, but its value to predict a positive radiolabelled choline positron emission tomography (PET)/computed tomography (CT) has been reported to be less robust than that of trigger PSA. To explore the ability of the initial GS to predict the detection rate of recurrent PCa with ¹⁸F-fluorocholine (FCH) PET/CT in a large cohort of patients. Methods: Data of 1,000 patients who had undergone FCH PET/CT because of biochemical relapse of PCa between 2004 and 2013 were retrieved from four centers’ databases. Continuous data were compared by t-Student test or ANOVA test, and categorical variables by the chi-square test. Univariable and multivariable analysis were performed using logistic regression. Results: GS at diagnosis was ≤6 in 257 patients, 7 in 347, and >7 in 396. A total of 645 PET/CT scans (64.5%) were positive for PCa recurrence. Eighty-one percent of the positive PET/CTs were in patients with PSA≥2 ng/mL, 43% and 31% being found among patients with 1 ng/mL>PSA<2 ng/mL, and PSA≤1 ng/mL, respectively; 78.8% of patients with a positive PET/CT had GS>7. FCH PET/CT scans were negative in 300 patients, 44% of whom had GS≤6, 35% had GS=7 and 17% had GS>7. PET/CTs were rated as doubtful in only 5.5% of patients (median PSA: 1.8 ng/mL). With GS>7, the detection rate of FCH PET/CT was 51%, 65% and 91% for PSA<1 ng/mL, 1 ng/mL>PSA<2 ng/mL, and PSA>2 ng/mL, respectively. At univariable and multivariable analysis, both GS=7 and GS>7 were independent predictors for a positive FCH PET/CT (odds ratios: 0.226 and 0.330, respectively; both with P < 0.001). Conclusion: High GS at diagnosis is a strong predictive factor for a positive FCH PET/CT scan for recurrent PCa, also at a low biochemical failure level (PSA ≤1 ng/mL).