Test reveals whether deadly skin cancer has
MIAMI - AP World News via NewsEdge Corporation : An experimental new test for people undergoing surgery for melanoma can apparently reveal whether deadly traces of the cancer have already spread to other parts of the body.
Melanoma is highly curable if caught early, but doctors often cannot be sure whether it has already spread. This new test could be the first simple and accurate way of revealing this spread so that the disease can be treated aggressively.
Melanoma is the most dangerous form of skin cancer.
The new test, developed at the John Wayne Cancer Institute in Santa Monica, California, looks for certain proteins that show up mostly on cancer tissue. Dr. Rishab Gupta reported on preliminary use of the test Monday at a cancer society conference in Miami.
The protein is called tumor antigen 90, or TA-90. Doctors look for it using a simple blood test that checks for antibodies to TA-90. If the protein is present, the sample turns yellow.
If TA-90 shows up after the cancer has been surgically removed, it means the cancer probably still exists somewhere else in the body.
For these patients, doctor are likely to remove a much larger section of tissue around the tumor, take out lymph nodes and offer chemotherapy, radiation or experimental cancer vaccines.
``It would be reassuring to have a simple test that tells us if the tumor has spread or we have gotten it all,'' said Dr. Charles McDonald, a dermatologist from Brown University. ``This would be the first effective test.''
Gupta and others tried out the test on 57 such early-stage patients whose disease turned out to have spread. They found that 43 had a positive TA-90 test.
Five years after surgical removal of melanoma, they found that 88 percent of patients with no signs of TA-90 were still alive, compared with 63 percent of those who tested positive for the protein.
It's still too early to know if the test might reveal melanoma in people who show no outward signs of the disease.
But because the test would be cheap and easy to perform, Gupta said ``it could be of enormous benefit in nationwide screening programs.''
Gupta said his institute is negotiating with biotechnology companies. that could develop the test for commercial release.
The test is the latest development in what some call molecular detection of cancer, which look for traces of proteins unique to the disease. The most widely used example is the PSA test for prostate cancer; it reveals abnormal levels of a protein produced by dividing prostate cells.
One such test still in development attempts to spot ovarian cancer early by detecting lysophosphatidic acid, or LPA. Dr. Yan Xu of the Cleveland Clinic Foundation said this shows promise for early detection, but more work is necessary to reduce the chances of false alarms.
She estimated that 50 of every 10,000 women have ovarian cancer. Testing for LPA would find 45 of them. However, it would erroneously label 1,000 women as having this form of cancer.