Updated

When Al Piazza learned he had prostate cancer, his first thought was, “Let’s get this out and be done with it,” he says. But his urologist, Jeremy Lieb, said the side effects of treatment could be more harmful than the cancer itself.

Dr. Lieb ran a genetic test on the patient’s biopsy sample, which calculated that Mr. Piazza, then 70 years old, had only a 3 percent chance of dying from prostate cancer over the next 10 years if he left the tumor untreated.

Four years later, the retired AT&T manager from Discovery Bay, Calif., has been monitoring his cancer with regular blood tests and imaging scans and says he is comfortable leaving it alone. “My feeling is—it’s there, but it’s not going to kill me,” Mr. Piazza says.

The procedure done on Mr. Piazza’s tumor sample, called Prolaris by Myriad Genetics, is one of several new prostate-cancer tests that aim to reduce detection and treatment of tumors that are likely to be harmless while still spotting those that are lethal.

More on this...

That has been a daunting challenge in recent years. Routine screenings for prostate cancer, using blood tests for prostate-specific antigen, or PSA, have dramatically increased early detection of the disease. More than 99 percent of cases are curable today. Most of the cancers that prostate screenings find are so slow-growing they are effectively harmless, experts say. Still, because some cancers are aggressive and deadly, most men have opted for treatment with surgery or radiation despite a significant risk of incontinence or impotence.

Click for more from The Wall Street Journal.