Diagnostic and prognostic value of bladder cancer-related transcript markers in urine

Abstract

Purpose: Since cytology as the current "gold standard" for noninvasive detection of bladder cancer (BCa) is characterized by a relatively low sensitivity, urinary transcript levels of survivin (SVV), Ki-67 and cytokeratin 20 (CK20) were evaluated as alternative or complementary biomarkers. Furthermore, their prognostic value was investigated.

Methods: Voided urine samples from 105 BCa patients and 156 controls were included. Total RNA was isolated from urine pellets and reverse-transcribed into cDNA. Expression levels of SVV, Ki-67 and CK20 were determined by quantitative PCR and normalized to the housekeeping gene TBP. Diagnostic performance of transcript markers and cytology was assessed by receiver operating characteristic (ROC) curve analyses. The prognostic value of the transcript markers was calculated by Cox proportional hazards models.

Results: ROC analyses resulted in AUC values between 0.71 (Ki-67) and 0.86 (CK20), indicating an appropriate diagnostic power. Using specifically defined cutoff values, the expression levels of the assessed biomarkers were significantly higher in urine specimens from BCa patients compared to control group (Mann-Whitney U test p < 0.001). Specificity ranged from 75% (SVV) to 84% (CK20) and sensitivity from 56% (Ki-67) to 87% (CK20). In combination with cytology, the sensitivity increased up to 97% (CK20). With regard to prognostic power, only SVV showed a significant, but not independent impact on the risk of recurrence (p = 0.008).

Conclusions: Quantitative assessment of tumor-related transcript markers, particularly of CK20, may serve as a noninvasive method to identify patients with BCa. Moreover, SVV appears to be useful as a marker for a high risk of recurrence.

Keywords: BIRC5; CK20; Ki-67; Survivin; Urine; Urothelial carcinoma.

Fig. 1

Comparison of the relative expression levels of Ki-67 (a), SVV (b) and CK20 (c) in urine. The relative expression of the transcript markers in urine of BCa patients, patients with chronic cystitis and healthy volunteers are illustrated by box plots. The bottom and the top of the box plots represent the first and the third quartile. The median is illustrated by a solid line inside the box. The horizontal lines below and above the box mark the lowest and the highest values, which are no outlier or extreme values. Outliers (circles) are located 1.5 to 3 box lengths away from the bottom or the top of the box; extreme values (asterisks) show a distance of more than 3 box lengths

Fig. 2

Kaplan–Meier curves for the recurrence-free survival (RFS) as a function of the expression of Ki-67 (a), SVV (b) and CK20 (c). The patients were dichotomized by the median of the relative expression levels of the analyzed genes. Differences in RFS rates between both groups were calculated by the log-rank test. A step in the curve represents an event (recurrence). Censored cases (+) mark patients that developed no recurrence during the follow-up or withdraw from the study

Fig. 3

Kaplan–Meier curves for the progression-free survival (PFS) as a function of the expression of Ki-67 (a), SVV (b) and CK20 (c). The patients were dichotomized by the median of the relative expression levels of the analyzed genes. Differences in PFS rates between both groups were calculated by the log-rank test. A step in the curve represents an event (progression). Censored cases (+) mark patients that developed no recurrence during the follow-up or withdraw from the study