Urothelial cancer refers to cancer of the lining of the
urinary system and is most common in the bladder (rather than the kidney or
ureter). The modern, standard evaluation
of a patient with suspicion of urothelial cancer involves axial imaging of the
upper tract and bladder with an associated cystoscopy and urinary
cytology. A number of tests have been
developed to supplant or act as adjuncts to the standard urothelial bladder
cancer evaluation. However, the current
regimen of cystoscopy and urine cytology will detect 90% of urothelial bladder
cancers. This blog will review some of the common alternative urinary markers for
bladder cancer used in practice.
Urinary cytology is the microscopic examination of cells found in the urine. Cytology was
first developed by Papanicolaou in 1945 and remains the gold standard urine
test for the evaluation of suspected malignancy. The sensitivity (meaning a negative test
rules out disease) ranges from 40-60%, however the specificity (a positive test
indicates cancer) is high, ranging from 94-100%. The sensitivity and specificity of a urinary
cytology depends on the tumor grade, tumor stage, the number of samples
evaluated and the experience of the cytopathologist who evaluates the
sample. In addition, instrumented
samples (i.e. from a bladder wash during cystoscopy) have a higher yield and
better sensitivity that voided urine.[1]
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Urinary cytology demonstrating cancer cells. From http://www.pathologypics.com/PictView.aspx?ID=106 |
FISH stands for Fluorescence
in situ Hybridization and refers to a technique where fluorescently-labeled DNA
probes are designed to bind to intranuclear chromosomes (the genetic material
of cells). While they can be used for a variety of cancers, FISH probes have been developed to look for common genetic abberations in bladder cancer including aneuploidy of chromosomes 3, 7, 17 and homozygous loss of 9p21.
Compared to urinary cytology, the sensitivity
and specifity are 79% and 70% respectively.
FISH is highly dependent on an experienced laboratory to process and
interpret the results of each test, however has been demonstrated to have a
sensitivity dramatically improved when compared to urinary cytology. Importantly, the sensitivity of FISH improves
with increasing grade and stage of bladder tumors. In some patients, FISH can provide confidence
that no cancer is present. However,
false positive tests are relatively common and may indicate a “precurrence” of cancer
or genetic abnormalities that exist in the normal urothelium. The role of FISH in the everyday management of
bladder cancer is not well-defined and utility may vary by practitioner.[2-4]
NMP-22 (Nuclear
Matric Protein) is a molecule preferentially shed into the urine by bladder
cancer cells to that NMP22 levels are, on average, 20x higher in patients with
bladder cancer than those without cancer.
Unfortunately, the cutoff values for an abnormal NMP22 are not well
established and a higher NMP22 level does not correlate to worse grade or stage
of disease. The sensitivity and
specificity of NMP22, using a cutoff of 10units/mL, are reported to be 49% and
87% respectively. The sensitivity does
improve for higher stage tumors.
However, false positives have been noted in patients with active urinary
tract infections and hematuria.[5-7]
A number of other promising markers are in development but
are not clinically available for most patients.
These include tests like Lewis
Blood Group Antigen X which is absent in normal cells and present in
urothelial cancer cells of the bladder.[8]
CK20 and CYFRA21.1 are proteins found in the cytoskeleton of bladder cancer cells
and can be detected by protein or RNA analysis of the urine.[9] Metabolomics is a promising avenue for
discovery, where metabolites in the urine can vary between patients with and
without cancer. Preliminary studies
demonstrate varying metabolite patterns for patients with and without cancer,
however no test has proven superior to cystoscopy and cytology as of yet.
[1] Volpe A, Racioppi M, D'Agostino D, Cappa E, Gardi M,
Totaro A, Pinto F, Sacco E, Marangi F, Palermo G, Bassi PF. Bladder tumor markers: a review of the
literature. Int J Biol Markers. 2008 Oct-Dec;23(4):249-61.
[2] Sarosdy MF, Schellhammer P, Bokinsky G, Kahn P, Chao R,
Yore L, Zadra J, Burzon D, Osher G, Bridge JA, Anderson S, Johansson SL, Lieber
M, Soloway M, Flom K. Clinical
evaluation of a multi-target fluorescent in situ hybridization assay for
detection of bladder cancer. J Urol. 2002 Nov;168(5):1950-4.
[3] van Rhijn BW, van der Poel HG, and van der Kwast TH:
Urine markers for bladder cancer surveillance: a systematic review. Eur Urol
2005; 47: pp. 736-748
[4] Yoder BJ, Skacel M, Hedgepeth R, et al: Reflex UroVysion
testing of bladder cancer surveillance patients with equivocal or negative
urine cytology: a prospective study with focus on the natural history of
anticipatory positive findings. Am J Clin Pathol 2007; 127: pp. 295-301
[5] Atsu N, Ekici S, Oge OO, et al: False-positive results
of the NMP22 test due to hematuria. J Urol 2002; 167: pp. 555-558
[6] Grossman HB, Soloway M, Messing E, et al: Surveillance
for recurrent bladder cancer using a point-of-care proteomic assay. JAMA 2006;
295: pp. 299-305
[7] Keesee SK, Briggman JV, Thill G, and Wu YJ: Utilization
of nuclear matrix proteins for cancer diagnosis. Crit Rev Eukaryot Gene Expr
1996; 6: pp. 189-214
[8] Sheinfeld J, Reuter VE, Melamed MR, et al: Enhanced
bladder cancer detection with the Lewis X antigen as a marker of neoplastic
transformation. J Urol 1990; 143: pp. 285-288
[9] Ramos D, Navarro S, and Villamon R: Cytokeratin
expression patterns in low-grade papillary urothelial neoplasms of the urinary
bladder. Cancer 2003; 97: pp. 1876-1883