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Purpose
To highlight a new imaging acquisition protocol during 18F-fluorocholine PET/CT in patients with biochemical recurrence after RP.Methods
A total of 146 patients with PSA levels between 0.2 and 1 ng/ml with negative conventional imaging who did not receive salvage treatment were prospectively enrolled. Imaging acquisition protocol included an early dynamic phase (1–8 min), a conventional whole body (10–20 min), and a late phase (30–40 min). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were measured. Univariable and multivariable analyses were performed to identify independent predictors of positive PET/CT.Results
The median trigger PSA was 0.6 ng/ml (IQR 0.43–0.76). Median PSA doubling time (PSA DT) was 7.91 months (IQR 4.42–11.3); median PSA velocity (PSAV) was 0.02 ng/ml per month (IQR 0.02–0.04). Overall, 18F-fluorocholine PET/CT was positive in 111 of 146 patients (76 %). Out of 111 positive examinations, 80 (72.1 %) were positive only in the early dynamic phase. Sensitivity, specificity, PPV, NPV, and accuracy were 78.9, 76.9, 97.2, 26.3, and 78.7 %, respectively. At multivariable logistic regression, trigger PSA ≥ 0.6 ng/ml [odds ratio (OR) 3.13; p = 0.001] and PSAV ≥ 0.04 ng/ml per month (OR 4.95; p = 0.004) were independent predictors of positive PET/CT. The low NPV remains the main limitation of PET/CT in this setting of patients.Conclusions
The increased sensitivity, thanks to the early imaging acquisition protocol, makes 18F-fluorocholine PET/CT an attractive tool to detect prostate cancer recurrences in patients with a PSA level <1 ng/ml.The pentose phosphate pathway (PPP) has been shown to play an important role in the metabolism of cancer cells. The transketolase-like 1 gene (TKTL1) encodes an enzyme representing an essential component of this pathway. Its expression has been demonstrated to correlate with stage and outcome in various tumors. The aim of the present study was to assess expression patterns and the prognostic role of TKTL1 in muscle-invasive bladder cancer (MIBC).
Patients and methodsThe expression of TKTL1 was assessed in a tissue microarray consisting of histopathologically benign and malign tissue of 112 patients who underwent radical cystectomy due to MIBC. Cytoplasmatic and nuclear expression were assessed by immunohistochemistry and compared separately with clinicopathologic parameters and outcome.
ResultsCytoplasmatic expression of TKTL1 was exclusively present in tumor tissue. In contrast, the proportion of nuclei positive for TKTL1 was higher in histopathologically benign tissue compared with malign tissue. No correlation was observed between cytoplasmatic or nuclear TKTL1 expression and tumor stage, grade or the presence of metastases. Patients with lymph node involvement showed a decreased frequency of cytoplasmatic expression compared with node-negative patients (p = 0.01). However, no further correlation was observed between the expression of TKTL1 and clinical outcome of patients.
ConclusionsThe present study shows that the cytoplasmatic expression of TKTL1 is specific for MIBC tissue compared with histopathologically benign urothelium. This specific expression is present in a subgroup of MIBC potentially identifying patients with activated PPP suitable for a targeted inhibition of sugar metabolism. In contrast to other malignancies, TKTL1 shows no prognostic significance in MIBC.
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