Genetic test can gauge prostate cancer risk level

A genetic test to gauge the aggressiveness of prostate cancer may help tens of thousands of men each year decide whether they need to treat their cancer right away or can safely monitor it.

The test joins another one that recently came on the market. Both analyse multiple genes in a biopsy sample and give a score for aggressiveness, similar to tests used now for certain breast and colon cancers.

Doctors say such tests have the potential to curb a major problem in cancer care — over-treatment.

Prostate tumours usually grow so slowly they will never threaten a man’s life, but some prove fatal and there is no reliable way now to tell which ones will. Treatment with surgery, radiation or hormone blockers isn’t needed in most cases and can cause impotence or incontinence, yet most men are afraid to skip it.

“We’re not giving patients enough information to make their decision,” said Dr Peter Carroll, chairman of urology at the University of California, San Francisco. “You can shop for a toaster” better than for prostate treatment, he said.

He led a study of the test — the Oncotype DX Genomic Prostate Score.

The results suggest the test could triple the number of men thought to be at such low risk for aggressive disease that monitoring is a safe option. Conversely, the test also suggested some tumours were more aggressive than doctors had believed.

Independent experts say such a test is desperately needed but that it’s unclear how much information this one adds or whether it will be enough to persuade men with low-risk tumours to forgo treatment, and treat it only if it gets worse. Only 10% who are candidates for monitoring choose it now.

“The question is, what’s the magnitude of difference that would change the patient’s mind?” said Dr Bruce Roth, a cancer specialist at Washington University in St Louis.

One man may view a 15% chance that his tumour is aggressive as low risk “but someone else might say, ‘Oh my God, let’s set the surgery up tomorrow’. I don’t think it’s a slam dunk.”

The test was developed by Genomic Health, which has sold a similar one for breast cancer since 2004. Doctors at first were wary of it until studies in more groups of women proved its value, and the same may happen with the prostate test, said Dr Len Lichtenfeld, of the American Cancer Society.

The company will charge $3,820 (€2,900) in the US for the prostate test and says it can save money by avoiding unnecessary treatment.