A new test can help distinguish aggressive prostate cancer from less threatening ones, potentially saving many men from unneeded operations for tumors that would never hurt them, researchers are reporting.
The test, developed by Genomic Health, could triple the number of men who could confidently monitor their tumors rather than undergo surgery or radiation treatments, according to the company and to researchers.
Results of a study assessing the test's performance will be presented Wednesday at the annual meeting of the American Urological Association in San Diego.
Many of the 240,000 cases of prostate cancer diagnosed each year in the United States are considered to pose a low risk of hurting or killing the man. But sometimes those assessments are wrong. So many men, reluctant to take the chance, undergo treatments that can cause impotence and incontinence.
"It's very hard to tell a surgeon 'I'd like to leave a cancer in place,' " said Dr. Jonathan Simons, president of the Prostate Cancer Foundation, a research and advocacy organization. "Having objective information is going to help a lot of patients make that decision."
Dr. Simons, who was not involved in the study, said the development of new genetic tests like the one from Genomic Health represented a "watershed," akin to going from pulse rate measurements to electrocardiograms in cardiology.
Still, some experts said it was too early to assess how accurate the test really was and whether it would make a difference in men's decisions. Insurers are going to want to know that before deciding to pay for the test, which will be available starting Wednesday at a list price of $3,820.
Even the senior investigator of the study, Dr. Peter R. Carroll, said he was not sure.
"Certainly for a group of men it will have an impact," Dr. Carroll, who is chairman of urology at the University of California, San Francisco, said in an interview. "The question is how many men and how many physicians."
The new test, which is called the Oncotype DX Prostate Cancer Test, is one of more than a dozen coming to market that use advanced genetic methods to help better manage prostate cancer. The most direct competitor to the Oncotype test is likely to be the Prolaris test, introduced last year by Myriad Genetics.
But Genomic Health's test has attracted attention because of the company's track record. It already sells a similar test for breast cancer, also Oncotype DX, that is widely used to help women decide whether they can forgo chemotherapy after their tumor is surgically removed.
Some analysts say that with the breast cancer test facing intensified competition, the company's future growth could hinge on the prostate test, which could take time to gain acceptance. Genomic Health's stock closed Tuesday at $33.87, up 1 percent.
The test looks at the activity level of 17 genes in the biopsy sample and computes a score from 0 to 100 showing the risk that cancer is aggressive.
To see how well the test worked, testing was performed on archived biopsy samples from 412 patients who had what was considered low or intermediate-risk cancer but then underwent surgery.
In many such cases, the tumor, which can be closely studied after it is surgically removed, turns out to be more aggressive than thought based on the biopsy, which looks at only a tiny sample of the tumor.
The researchers found that the Oncotype test predicted such unfavorable pathology more accurately than existing methods, which depend mainly on the Gleason score based on how the biopsy sample looks under the microscope.
Genomic Health said that 26 percent of the samples were classified as very low risk by its test, compared to only 5 to 10 percent for the existing methods. In some cases, however, the new test showed the cancer to be more aggressive than the existing methods.
Some experts not involved in the study were cautiously optimistic.
"They showed a pretty good correlation with the score and how it predicts things," said Dr. E. David Crawford, a professor of urology, surgery and radiation oncology at the University of Colorado. He has consulted for Myriad Genetics and said he might become a consultant to Genomic Health.
Dr. Stacy Loeb, assistant professor of urology at New York University, said, "I think it will help — they definitely showed it improves upon what we are using now." She said it was not clear, however, how the Genomic Health and Myriad tests compared to each other.
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