Detection of prostate cancer (PCa) recurrence with 18F-fluorocholine (FCH) PET/CT in relation to Gleason score (GS) of primary tumor: Experience on 1,000 patients (pts)

Objectives To explore the ability of GS to predict the detection rate of FCH PET/CT in recurrent PCa at any PSA levels, in a large cohort of pts.

Methods FCH PET/CTs of 1030pts with biochemical relapse of PCa were reviewed from three institutes’ databases. 265 pts had GS <7, 330 had GS=7 and 435 had GS>7. PSA levels were ≤1, 1>PSA<2 and ≥2 in 299, 139 and in 592 pts, respectively. All pts had a PET/CT scan at 45-60 minutes after injection of 3-3.5 MBq/kg of FCH (IASOcholine, Austria). Continuous data were compared by t-Student test and categorical variables by chi-square test. Univariate and multivariate analysis were computed.

Results 630 (61%) pts showed positive FCH PET/CTs for PCa recurrence. Local relapses were in 272 cases, lymph nodes metastases in 292 and distant metastases in 323. Positive PET/CTs were detected in 81% of pts with a PSA≥2, in 44% with 1>PSA<2 and in 30%with PSA≤1. At the same time, positive PET/CTs were in 51%, 30% and 19% of pts with GS>7, GS=7 and GS<7, respectively. Negative FCH PET/CTs were detected in 343 (33.3%) pts: 189 with a PSA≤1, 65 with a 1>PSA<2, 89 with a PSA≥2. Among pts with negative FCH scans, 36% had GS<7, more 36% had GS=7 and 28% had GS>7. Doubtful PET/CTs were in only 5.5% of pts. FCH detection rate was 45%, 24% and 11% at PSA <1 in pts with GS>7, GS=7 and GS<7, respectively; it was 64%, 35% and 31% at 1>PSA<2 and GS>7, GS=7 and GS<7, respectively and it was 91%, 74% and 71% at PSA≥2 and GS>7, GS=7 and GS<7. At univariate and multivariate analysis both GS=7 and GS>7 resulted as independent predictive factors of a positive FCH PET/CT (ORs: 0.19 and 0.31; p<0.001).

Conclusions Higher GS has shown to be a strong predictive factor for a positive FCH PET/CT finding of recurrent PCa also at low biochemical failure (PSA ≤1ng/ml).