The Cleveland Clinic wrote this:
Predicting prostate cancer-specific mortality
The first research project looked at the death rate among prostate cancer survivors after radical prostatectomy, a procedure that surgically removes the prostate gland.
Post-surgery follow up typically includes prostate-specific antigen (PSA) screening to see if there is a recurrence. PSA is a protein produced by cells in the prostate gland. An elevated level in the blood usually is an indicator of cancer or other disorder. Radical prostatectomy patients usually are screened every three to six months for the first five years after surgery, and then annually after that to see if there is a recurrence of PSA.
But are PSA screenings the most accurate way to predict recurrence of cancer? Should they be the primary tool for counseling patients, making clinical decisions, and placing patients into clinical trials? The research found the answer to be “no.”
“Within 15 years of PSA recurrence, men are more likely to die from other causes than from prostate cancer. Clearly, using PSA recurrence as the principal way to assess treatment success or predict mortality is limited,” Dr. Kattan said.
As a result, the researchers created and validated a two-dimensional diagram designed to allow approximate computation called a nomogram that accurately predicts prostate cancer-specific mortality over 15 years. It includes a number of factors, not just PSA screenings.
“This predictive tool looks at more variables than just PSA recurrence and considers adverse clinical features. This more complete picture provides important and useful information for patients and physicians regarding treatment decisions for localized prostate cancer,” Dr. Kattan said. The research appeared in Journal of Clinical Oncology ( http://jco.ascopubs.org/ , published online July 27, 2009).
http://www.lerner.ccf.org/news/notations/2009/7/2.php
I hope this helps.