Assay plus cystoscopy sharpens bladder cancer diagnosis
Combination of an immunofluorescence test and cytology may improve quality of bladder cancer diagnostics.
Urine cytology is controversial. It is sensitive for high-grade cancers, with estimates ranging from 75% to 90%. But for low-grade cancers, the sensitivity results are poor-10% to 20%-prompting some urologists to abandon using it.
"No single test gives us the right answer. We're still unsure as to what is the most effective test," Anobel Y. Odisho, MD, a resident in urology at UCSF, told Urology Times.
The ImmunoCyt fluorescent assay (Diagnocure, Inc., Quebec City) uses a combination of three monoclonal antibodies to target two mucins and high-molecular-weight carcinoembryonic antigen in exfoliated urothelial cells in a voided urine sample.
As reported at the AUA annual meeting, from January 2007 to June 2008, patients presenting at UCSF who had "atypical" or "indeterminate" cytology results routinely underwent ImmunoCyt tests. Dr. Odisho, working with Badrinath Konety, MD, MBA, and colleagues, took a retrospective look at the records of the patients to see whether their subsequent workup with cystoscopy and medical history indicated the presence of bladder cancer. Evidence of a tumor or an erythematous lesion was considered to be an "abnormal" cystoscopy result.
Of the 222 patients who had ImmunoCyt tests, 182 had cystoscopy within the subsequent 90 days, which the investigators considered relevant. Thirty-five of those patients had no prior history of carcinoma, and 147 had had transitional cell carcinoma, including 66 with low-grade cancers.
Addition of the ImmunoCyt test showed which of the 35 patients with no previous history of cancer had no cystoscopic abnormalities with 100% sensitivity and a negative pre-dictive value of 100%. Among the 147 patients with a history of cancer, the negative predictive value was still fairly high: 87.3%.
Further, among those who did have a cancer history, the negative predictive value of the ImmunoCyt test was higher (92.6%) in those who had had low-grade cancers, but remained fairly high (81.8%) in those who had had high-grade cancers or carcinoma in situ.
According to this analysis, ImmunoCyt's value is to save patients from unnecessary cystoscopy when their cytology results remain unclear. For those with no history of cancer, the test may predict a negative cystoscopy.
