NEW YORK, Jun 02 (Reuters Health) - An experimental test that detects a
specific protein in blood samples appears to be promising as a screening test
for breast cancer, the manufacturer, Matritech, Inc. of Newton, Massachusetts
announced on Thursday.
The test detects nuclear matrix protein (NMP), a protein that may be
elevated in the blood of people with cancer. The test is approved in the US,
Japan and Europe for bladder cancer screening, but not for other purposes.
In a new study, the test was used in 78 women who had early or advanced
breast cancer, a precancerous condition, or no cancer at all. The test correctly
identified all cancer cases, and four out of five women with a precancerous
condition known as ductal carcinoma in situ.
"We detected every case of cancer, and ruled out cancer for all normal
samples," David L. Corbet, president and COO of Matritech, said. "Based on
this...we consider 'proof of concept' complete."
However, due to the small number of specimens, which came from patients that
the company knew did or did not have cancer ahead of time, Dr. Clifford Hudis,
chief of breast cancer medicine services at Memorial Sloan-Kettering Cancer
Center, expressed concerns that the test may not be accurate with larger patient
populations.
"If (the test) has even a low rate of false-positive results...(and you
test) a million people...then you have thousands, literally, of positive results
that don't indicate cancer," he said in an interview with Reuters Health.
False-positive results occur when a test signals the presence of a disease, but
the patient does not in fact have the disease.
Since the 78 specimens of the trial are the entire scope of Matritech's
testing of NMP66 so far, "the company will be engaging in a much larger clinical
trial, perhaps by the end of the year," a Matritech spokesperson told Reuters
Health. "Should the results and the data prove encouraging, (the company) may be
in a position at that point to either broaden the trial or go right to the (US
Food and Drug Administration)" to seek marketing approval.
"The company is not looking to replace mammography," he added. Mammograms,
x-rays of the breast, are used to screen women for breast cancer.
Citing difficulties sometimes encountered when performing mammography on
younger women, as well as errors that can occur with the interpretation of
mammograms, the spokesperson said that Matritech believes that the NMP66 test
may be used to complement the standard breast cancer screening procedure.
Hudis said that, in the setting of an abnormal mammogram, a test such as
NMP66 could be very useful in helping to determine cancer risk.
The test is covered by three patents issued to the Massachusetts Institute
of Technology, which are exclusively licensed to the company. Matritech said
that it has filed an additional four patents that seek coverage for the use of
NMPs in the management of breast cancer.
