Scientists measuring active DNA in prostate tumors have identified aggressive forms of the disease that are about three times more likely to kill patients within a few years, a study shows.
Screening for the genes, found in about 29 percent of patients in the study, may allow the most lethal types of prostate cancer to be pinpointed earlier and more definitively than current tests, researchers said today in a report in the Proceedings of the National Academy of Sciences.
More than 240,800 U.S. men will be diagnosed with prostate cancer this year and 33,700 will die, according to the National Cancer Institute. In some instances, it can take 10 years for the cancer to spread, spurring some doctors to advise watchful waiting for men older than 75 rather than immediate treatment that can include surgery. In other cases, the disease can move quickly, killing within a few years.
“We’ve begun the process of identifying genes which predispose poor outcomes,” said Arnold Levine, a study author and biologist at the Institute for Advanced Study in Princeton, New Jersey. “It’s an early indication.”
The study used data from 281 patients from Sweden who had been recruited between 1977 through 1999 that included their age, whether they died from the cancer and how long they survived. The scientists tested their tumor tissue for genetic expressions associated with prostate cancer.
“Stem-cell-like” gene activation patterns examined in the new test led researchers to identify two subtypes of prostate cancer that carried a 3.2-fold increased risk of death.
The current method for predicting prostate cancer involves a method of tumor grading based on how the malignant cells pattern themselves, called the Gleason system. Patients’ tumors are scored on the cell patterns, which are rated by their ability to mimic normal prostate gland structure. A low score means the cancer is similar to normal prostate tissue and is less likely to spread, whereas a high score means the cancer is more likely to spread, portending a poorer outcome.
A low Gleason score, however, doesn’t necessarily mean the cancer won’t turn hostile, researchers said. The gene test may help predict patients with low Gleason scores who will have poor survival, they said.
The results will need to be validated in a larger prospective trial, Levine said. His group has started that work. Early data may be available as soon as five years from now, and survival data in 10 to 15 years, he said.
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