CARPINTERIA, CalifA newly available fluorescent-based
immunocytologic test to detect superficial bladder cancer, ImmunoCyt, used in
conjunction with urinary cytology, will likely reduce the need for periodic
cystoscopies in patients with transitional cell bladder cancer and enhance the
early detection of recurrent disease.
"Examination of the urine under the microscope has been
found to be an inadequate way to detect recurrent bladder cancer. It requires
patients diagnosed with bladder cancer to undergo frequent cystoscopic
monitoring once surgical removal of any cancer has taken place," said
Edward Messing, MD, chairman, Department of Urology, University of Rochester
School of Medicine, Rochester, NY.
Because of this ongoing need to monitor for recurrences,
"tests that may lessen the need for such invasive procedures as cystoscopy
would be welcomed," Dr. Messing said during a telephone press conference.
He emphasized the importance of detecting low-grade tumors as soon as possible.
"ImmunoCyt utilizes three monoclonal antibodies specific
for two antigens expressed on the tumor cell surface," said Edward Barker,
MD, PhD, who moderated the conference. Dr. Barker is a pathologist and
president of Molecular Oncology International, Seattle, an independent
laboratory involved in evaluating the immunologic test.
With ImmunoCyt, Dr. Barker said, bladder cancer cells are
collected from a urine sample, filtered, spread on a slide, stained with the
fluorescently labeled antibody mixture, and scanned under darkfield microscopy
for the presence of red and/or green fluorescence on transitional cells. The
cost of the test is about $250.
ImmunoCyt is licensed by DAKO Corporation of Carpinteria,
California, from DiagnoCure, Inc. of Quebec City, Canada. The US Food and Drug
Administration granted commercial clearance for the ImmunoCyt test in March
Antibody Detects Mucin, CEA
The antibodies used in the ImmunoCyt kit are designed to
detect a mucin glycoprotein and a modified form of the carcinoembryonic antigen
(CEA). Importantly, the CEA antigen scored for by this test is separate and
distinct from the CEA antigen associated with colon cancer, diminishing the
possibility for cross-reactivity that could yield inaccurate results.
Dr. Barker pointed out that conventional cytology detects
low-grade tumors only about 40% of the time. When ImmunoCyt is used in
conjunction with cytology, this sensitivity rate increases to roughly 95%.
Moreover, the specificity of these combined tests ranges from 50% to 75%.
Michael Carter, MD, a urologist from Kelowna General Hospital,
British Columbia, Canada, reported similar sensitivity rates. "We
performed ImmunoCyt tests on urine samples obtained from 34 patients previously
diagnosed with abnormalities on cystoscopy and detected 32 transitional cell
cancers," Dr. Carter said. "In our laboratory, the overall
sensitivity of ImmunoCyt plus cytology was 90.6%," he said, adding that at
this level of accuracy, the likelihood of a false-negative result is very low.
Dr. Messing said that "the single most immediate advantage
of this immunocytology test is its potential to reduce cystoscopies required
of patients with a more indolent form of bladder cancer," which should
also increase patient compliance with the necessary continual monitoring for
recurrence. For example, the manufacturer’s suggested monitoring schedule for
a low-risk patient (single tumor with negative cystoscopy exam at 3 months) is
Immunocyt plus cytology every 6 months and cystoscopy every 12 months.
Dr. Messing also said that while future large-scale prospective
studies are needed to fully evaluate the utility of such immunology-based
cytology tests, the current data are a good first step toward increasing the
detection rates of bladder cancer.
Notably, additional data in close to 60 patients from Dr.
Carter’s studies are pending and should bolster these initial