New clues in prostate cancer therapy

A man has a 17% lifetime risk of being diagnosed with prostate cancer, for example, but a 3% risk of dying from it.

Yet about one in three prostate cancer patients who have surgery eventually show signs of a relapse, according to a study published today in the Journal of the American Medical Association.

Doctors have few reliable ways, however, to determine which of these relapses — detected by PSA tests — will be deadly and which will prove relatively harmless.

The article suggests that doctors might be able to combine three measurements to select those who need strong therapy.

•Time to recurrence: the time it takes after surgery to detect levels of PSA, or prostate-specific antigen, in the blood.

This protein, which is made by the prostate, should be undetectable after surgery if a patient is cancer-free.

The presence of PSA in the blood after surgery indicates that some tumor cells remain hidden in the body.

•PSA doubling time: the time it takes for the PSA level to double after surgery. This measures how quickly the cancer is growing.

•The Gleason score: a measure of aggressiveness assigned after examining prostate cancer cells under a microscope. Scores above 8 are considered the most dangerous.

In the study, men whose PSA doubled in less than three months survived an average of six years. Among these men, however, those whose cancer recurred in less than three years and who had Gleason scores of 8 to 10 survived about three years. After 15 years, no pros

tate-cancer-related deaths were found in men whose disease took more than three years to return and whose PSA took more than 15 months to double.

Men who are at high risk could benefit from aggressive treatments, such as hormone suppression and chemotherapy, Freedland says.

A study in the same journal reported another potential way to predict which prostate cancers are most worrisome.

Among patients treated with radiation, men had the greatest risk of death if their PSA increased by more than 2 nanograms per milliliter in the year before they were diagnosed.

Some experts say that doctors need to verify these results before changing the way they treat patients.

Mitchell Anscher, a professor at Duke University who wrote an editorial accompanying the articles, notes that hormone suppression and chemotherapy cause serious side effects.

Chemo can make patients very sick. Suppressing testosterone, sometimes called "chemical castration," can cause impotence, hot flashes and bone loss.