By Pam Belluck

New York Times News Service

They are among the most challenging prostate cancer patients to treat: about 150,000 men worldwide each year whose cancer is aggressive enough to defy standard hormonal therapy, but has not yet spread to the point where it can be seen on scans.

These patients enter a tense limbo which often ends too quickly with the cancer metastasizing to their bones, lymph nodes or other organs — sometimes causing intense pain.

Now, for the first time, researchers have results from two independent clinical trials showing that two different drugs help these patients — giving them about two more years before their cancer metastasizes. That means two additional years before pain and other symptoms spread and they need chemotherapy or other treatments.

“We’re going from rags to riches,” said Dr. Judd Moul, a professor of surgery and director of the Duke Prostate Center, who was not involved in either study. “Up until now, we haven’t had anything for these guys. We just had to tell them ‘We’ll keep an eye on it.’”

The studies, each involving more than 1,200 patients in countries around the world, were presented Thursday at the Genitourinary Cancers Symposium in San Francisco. They used very similar drugs — both androgen receptor inhibitors, which block testosterone from binding to prostate cancer cells and entering them.

The study of an experimental drug called apalutamide was published Thursday in the New England Journal of Medicine. The other study of a drug called enzalutamide, currently approved for treating prostate cancer that has already metastasized, has not yet been peer-reviewed for publication, the authors said.

Prostate cancer is the second most common cancer in men worldwide. The American Cancer Society estimates that in 2018, there will be about 164,690 new cases of prostate cancer and about 29,430 deaths. Worldwide, there were 1.1 million new cases and about 307,000 deaths in 2012, according to the most recent data available from the World Health Organization.

The patients in both studies were men who had previously received some treatment for prostate cancer, such as surgery or radiation, but who later began to show rapid increases in their prostate-specific antigen or PSA, a protein associated with prostate cancer. They did not respond to the standard treatment to suppress testosterone, called androgen deprivation therapy.

Each year, about 30,000 to 50,000 American men and about 150,000 worldwide, fall into this category, called nonmetastatic castration-resistant prostate cancer. (The medical term for blocking male hormones is chemical castration.) Globally, about 200,000 of the 4 million men with prostate cancer are estimated to have this diagnosis, said Dr. Matthew Smith, director of the Genitourinary Malignancies Program at Massachusetts General Hospital’s Cancer Center, who co-led the apalutamide study with Dr. Eric Small, deputy director of the Helen Diller Family Comprehensive Cancer Center at University of California, San Francisco.

Both studies were funded by the companies that make the drugs. The current list price of enzalutamide is more than $10,000 a month; a price hasn’t been set for apalutamide, which is not yet on the market, though the Food and Drug Administration has put it under priority review.