Quantitative analysis of keratin 18 in the urine of patients with bladder cancer

The level of urinary keratin was compared in patients with and without bladder cancer using the newly developed IRMAK-18. Patients with bladder cancer had higher levels of keratin (74.6 +/- 146.9) than normals (2.5 +/- 4.7). When the upper limit of normal was set at keratin less than 20 ng./ml., the test was highly specific (98%) for bladder cancer but had a sensitivity of only 46%. Adjusting to keratin less than 10 ng./ml. increased the sensitivity to 57% but decreased the specificity to 91%. Elevated keratins were associated with stage and grade, aneuploidy and disease history. The IRMAK-18 assay for keratin may be useful for monitoring the clinical progress of some patients.