NEW YORK (Reuters) -- Some prostate cancer cells contain a molecule that help them to "walk" out of a tumor, allowing the cancer to metastasize, or spread to other parts of the body, a new study suggests.
The molecule, called thymosin beta-15, may eventually be used to determine if prostate cancer is slow-growing and essentially harmless -- or an immediate threat that should be treated with radiation or surgery.
"It looks interesting, no doubt about it. I think it's an important discovery," said Dr. Donald Coffey, a professor of urology and oncology at the Johns Hopkins Hospital in Baltimore. "If cancer is aggressive, it goes to the bone. Having a potential marker in the cells that shows the metastatic potential of a cell would be a very important marker to have," he said.
The researchers discovered thymosin beta-15 in high levels in metastatic rat prostate cancer cells and at low levels in less invasive cancer cells, according to senior investigator Dr. Bruce Zetter, of the Harvard Medical School in Boston.
The protein was also found in human prostate cancer cells, according to the report in this week's issue of Nature Medicine. And it was also correlated with the Gleason score, a system used to rate cancer biopsy cells based on microscopic examination.
"When there is a high Gleason grade it doesn't bode well. A low Gleason grade is far less aggressive. But two thirds of prostate cancer tests are in the middle range and hard to predict. In that range, we really need to know more," said Coffey, who wrote an editorial accompanying the study.
Thymosin beta-15 may help doctors determine if cancer cells in the middle range of the Gleason score should be treated or left alone, he said. Unlike other cancers, prostate cancer can be extremely slow-growing and may not need treatment. Treatment carries some risk of complications, such as impotence or incontinence.
According to the report, thymosin beta-15 is involved in the production of actin, a structural protein that can help cells mobilize to other parts of the body.
SOURCE: Nature Medicine (1996;2:1322-1328)
