Using proteomic analysis, we previously identified calreticulin (CRT) as a potentially useful urinary marker for bladder cancer. Now, we have also identified γ γ γ γ-synuclein (SNCG) and a soluble isoform of catechol-o-methyltransferase (s-COMT) as novel candidates for tumor markers in bladder cancer, by means of proteomic analysis. In the process of establishing a superior tumor marker system, we investigated the diagnostic value of a combination assay of these three proteins. Voided urine samples were obtained from 112 bladder cancer and 230 control patients. Urinary CRT, SNCG, and s-COMT were measured as a combined marker by quantitative western blot analysis. Relative concentration of each protein was calculated and the diagnostic value of a concomitant examination of these markers was evaluated by receiver operator characteristic analysis. With the best diagnostic cutoff, the overall sensitivity of the combined markers was 76.8% (95% confidence interval, 69-81%) with a specificity of 77.4% (72-80%), while those of a single use of CRT were 71.4% and 77.8%, respectively. When evaluated in relation to tumor characteristics, such as grade, stage, size, and outcome of urinary cytology, the diagnostic capacity of the combined markers was equal to or better than that of CRT in all categories. Concomitant use of CRT, SNCG, and s-COMT had higher sensitivity for detection of bladder cancer than did single use of CRT. Our study suggests that use of this panel of markers will improve the diagnosis of bladder cancer and may allow the development of a protein microarray assay or multi-channel enzyme-linked immunosorbent assay. (Cancer Sci 2004; 95: 955-961) ladder cancer is a common urothelial cancer with an estimated 57,400 and 13,000 diagnosed cases per year in the United States and Japan, respectively. 1, 2) Approximately 70% of bladder cancers are superficial 3) and respond well to endoscopic transurethral resection. However, 50% to 70% of these patients experience tumor recurrence, and 10% to 15% of recurrent tumors progress to muscle invasive disease. 4) Because the propensity for local recurrence extends over the lifetime, patients with superficial bladder cancer must undergo life-long surveillance.Cystoscopy is the mainstay in diagnosing bladder cancer. However, this procedure is unsuitable for screening of large groups because of its invasiveness and expense. In addition, follow-up cystoscopy for bladder cancer patients treated endoscopically represents a considerable part of the workload of any urological unit. Therefore, new tests with high specificity and sensitivity that are easy to perform are needed for both screening and monitoring the response to treatment of bladder cancer. Voided urine cytology (VUC) has been used in both diagnosis and follow-up of superficial bladder cancer since its first description by Papanicolaou and Marshall in 1945, but it has poor sensitivity although high specificity, particularly in well-differentiated cancer.5) To date, several urine-based markers for bladder cancer have ...
