Doctors often miss the spread of prostate cancer to other parts of the body because the migrating cancer cells can be difficult to detect. The new test could help doctors adjust treatment to fight off the spreading cancer before it kills the patient, said lead investigator Donald Malins, principal scientist at the Pacific Northwest Research Institute in Seattle.
Prostate cancer is the most commonly diagnosed cancer among men in the United States and kills about 30,000 each year, according to the National Prostate Cancer Coalition. While prostate cancer is easily treatable in its early stages, many men are not diagnosed until it's too late.
Malins and colleagues used a DNA test they developed to examine prostate tissue samples from 49 men, some of whom suffered from prostate cancer. They report their findings this week in the Proceedings of the National Academy of Sciences.
Forty percent of the samples in healthy men older than 55 showed signs of damage to the DNA of the prostate. The damage is similar to that in men who actually have prostate cancer, suggesting that the healthy men may be in trouble down the line.
The information could give doctors a "heads-up" to "follow the patient closely with the expectation of detecting and treating cancer at an earlier stage," Malins said.
Researchers also discovered that their DNA test could predict which prostate cancer tumors would spread to other parts of the body. While prostate cancer cells undergo changes as they prepare to move beyond the prostate, there's currently no way to detect the spread other than checking other parts of the body, Malins said.
The test could allow doctors to take evasive action against the spread of the cancer, perhaps by removing the prostate itself to get dangerous tumor cells out of the body, Malins said.
Dr. Durado Brooks, director of prostate and colorectal cancers at the American Cancer Society, said the DNA test shows promise.
"A tool like this, if it bears out, could be very helpful in really having a clearer idea about who needs to be either worked up more aggressively for the possibility of metastasis [spread of cancer] or who needs to be followed closely," he said.
But Brooks added that much more research needs to be done to confirm that the DNA test actually works. "We're a long way from having any clinical applications for it," he said.
He said that the DNA test currently requires a biopsy of the prostate cancer. "We're not going to start biopsying everybody's prostate to see if they're at risk of prostate cancer," he said. And even if someone is found to be at risk, there's no guaranteed way to prevent prostate cancer, he added.
Malins said researchers are working on ways to give the DNA tests to patients in a clinic or even a doctor's office.