Urinary calreticulin in the diagnosis of bladder urothelial carcinoma

To evaluate the potential suitability of calreticulin (CRT) as a urinary marker for bladder cancer. Urine specimens were collected from patients with histologically confirmed bladder urothelial carcinoma (Group 1; n = 109), urological patients without urothelial carcinoma (Group 2; n = 60), and non-urological patients (Group 3; n = 40). We developed an enzyme-linked immunosorbent assay (ELISA) procedure using commercially available anti-CRT mono/polyclonal antibodies, and then measured the concentration of urinary CRT. Urinary CRT concentration of group 1 was significantly higher than group 2 and 3 (Mann-Whitney U-test, P < 0.001). Groups 2 and 3 were joined together and considered as a non-bladder cancer group (n = 100), and a cutoff value (2.85 ng/mL) was determined using receiver operating characteristic (ROC) analysis. The sensitivity, specificity, and the area under the curve were 67.9%, 80.0%, and 0.742, respectively. The overall sensitivity of voided urine cytology (VUC) was 39.0% (n = 105), and the sensitivity of urinary CRT was significantly superior to VUC (McNemar test, P < 0.001). Higher sensitivity was observed especially in Ta, G1-2, and <= 3 cm tumors. Urinary CRT may be useful for diagnosis of bladder urothelial cancer. However, given that its specificity is relatively low, further evaluation in larger series is needed to define its clinical usefulness.