Blood Test Can Detect Spread Of Prostate Cancer Terminal Patients Can Avoid Ineffective, Disabling Surgery
FOR THE RECORD: Wednesday, March 22, 1995 CLARIFICATION: In a story on Page A1 Tuesday about a new test to determine whether prostate cancer has spread beyond the gland. The Associated Press reported that the cancer is fatal if it has spread. Once it has spread beyond the prostate, the cancer is incurable. But only about 20-percent of people whose prostate cancer has spread die from the often slow-growing disease; the rest typically die of other causes.
A new blood test can tell whether prostate cancer has spread beyond the gland, enabling patients who are going to die anyway to avoid ineffective and disabling surgery, a study suggests.
The test, announced Monday by the American Cancer Society, could be available to doctors by the end of the year, said Dr. Carl Olsson, an author of the study. It still needs approval from the U.S. Food and Drug Administration.
Once prostate cancer has spread, it is fatal. A test to learn whether the disease has spread would allow such men to avoid prostate-removal surgery and its side effects, which can include impotence or incontinence.
Currently, the only way doctors can know for certain that the cancer has spread is through surgery to remove the gland.
Prostate cancer is the nation’s second-leading cancer killer of men. The cancer society predicts it will strike 244,000 American men this year and kill 40,400.
To detect it, doctors use the blood test PSA and the digital rectal exam. The PSA test looks for elevated levels of prostatespecific antigen, a substance the prostate gland makes to carry sperm. Cancer can push readings up.
If those tests turn up suspicious results, the patient undergoes a biopsy. If the biopsy shows cancer, doctors may perform other tests, such as a bone scan, to try to learn whether it has spread outside the prostate. But such tests are not generally reliable.
Olsson, head of Columbia University’s urology department, said about 20 percent of the men who undergo surgery will die later because the cancer had already spread.
In a study in the April issue of Cancer, the journal of the Atlanta-based cancer society, Columbia researchers described the new test, called enhanced reverse transcriptase-PCR for PSA. It was made by Dianon Systems of Stratford, Conn.
In the study, researchers used a technique called polymerase chain reaction, or PCR, to amplify the genetic material in the PSA and find it in the blood. If the test finds that the PSA is being produced by prostate cancer cells, then the cancer has escaped from the gland, the researchers said.
With the test, the researchers correctly diagnosed that prostate cancer had spread in 72 percent of the cases later confirmed through surgery. The test was also accurate 88 percent of the time in predicting those patients whose cancer had not spread. The study was based on 94 patients.
Dr. Valentine Carter, a urologist at Johns Hopkins University, said the study “could be very important,” but more research is needed to support the conclusions.
No study has yet shown that screening leads to greater cancer survival rates, although increased screening has increased the percentage of cases in which the cancer is caught early.