Urine sample derived CK20- and IGF2-expression as biomarker for the detection of bladder cancer
Sources of Funding: Supported by European Regional Development Fund.
Introduction
Cytokeratin 20 (CK20) and Insulin-like growth factor 2 (IGF2) were previously proposed to be elevated in patients with bladder cancer (BCa). A two cohort design validation study was used to assess the relevance for BCa detection of both markers in urine samples. The results were compared to voided urine cytology (VUC).
Methods
RNA isolation was carried out using 5 ml spontaneous urine samples of 196 and 97* histologically positive BCa patients for the test and validation* cohort, respectively. Additionally patients with benign urological diseases, nephrolithiasis and unconfirmed BCa suspicion as well as healthy control subjects were included for a total of 103/50* control subjects in the test and validation* cohort. Urinary mRNA levels were determined by qPCR and the results were normalized as molecule ratio to RPLP0. Receiver operating characteristic curves and corresponding AUC values were used to evaluate the diagnostic performance of both markers. Optimal cut-off values were determined by Youden Index.
Results
Urinary mRNA levels were significantly elevated 3.4/11*-fold for CK20 and 188/64*-fold for IGF2 in BCa patients compared to controls in the test and validation* cohort, respectively. IGF2 performed slightly better with an AUC of 0.83 for both cohorts compared to CK20 with an AUC of 0.78 and 0.82* for the test and validation* cohort, respectively. Combined analysis of IGF2 and CK20 with at least one positive marker resulted in a sensitivity (0.78/0.90*) and specificity (0.88/0.84*) similar to that of VUC. The sensitivity of VUC in combination with IGF2 and CK20 was considerably increased (0.95/0.93*) while specificity was slightly reduced (0.72/0.84*) compared to VUC alone in the test and validation* cohort.
Conclusions
Expressions of IGF2 and CK20 correlated significantly with BCa with a diagnostic performance similar to VUC. Combined analysis of voided urine cytology together with expression levels of CK20 and IGF2 clearly enhances overall test performance. Therefore, its relevance for BCa diagnosis should be evaluated in a larger cohort.
Funding
Supported by European Regional Development Fund.
Doreen Huebner
Manja U. Boehme
Alexander Herr
Ulrike Heberling
Oliver W. Hakenberg
Daniela Jahn
Marc-Oliver Grimm
Astrid Enkelmann
Daniel Steinbach
Susanne Fuessel
Manfred P. Wirth