A signaling protein that is key to prostate cancer cell growth is turned on in nearly all recurrent prostate cancers that are resistant to hormone therapy - Stat5 - has been found by scientists at Jefferson's Kimmel Cancer Center in Philadelphia.

Men with primary prostate cancer usually have either surgery or radiation, whereas subsequent disease is frequently treated by hormone therapy. But if the cancer recurs again, years later, it can be more aggressive and typically fails to respond to hormone treatment.

In previous work, the researchers showed that when Stat5 is turned on in primary prostate cancer, men are more likely to have recurrent disease.

In the current study, the team examined human prostate cancer cells of 198 patients with prostate cancer recurrence. They found that Stat5 was active in 74 percent of all recurrent prostate cancers.

Of these patients, 127 had been treated with androgen deprivation therapy. The researchers found Stat5 was active in 95 percent of these hormone resistant tumors, meaning it was more likely to be active if the patient had been treated with hormone deprivation therapy.

Findings will appear January 1, 2008 in the journal Cancer Research.

Find more details from EurekAlert.

[In Photo: A Primer on Prostate Cancer: The Empowered Patient's Guide (Paperback) from Amazon]