By Lorna Benson, Minnesota Public Radio News

When treating cancer patients who suffer a second bout of the disease, doctors know catching the recurrence soon is crucial to the patient’s chances of survival.

But that’s been a challenge with prostate cancer, because doctors depend on a test that measures levels of prostate-specific antigen, or PSA, in the blood. PSA is a protein produced by prostate cells, and when men have prostate cancer their levels of the protein are often elevated.

In men with recurrent disease, rising PSA levels can suggest that their cancer isn’t cured.

“It’s like a puff of smoke that’s signifying an early fire,” said Dr. Eugene Kwon, urologist at Mayo Clinic who treats patients with advanced prostate cancer.

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