An accurate, straightforward method to predict prostate cancer risk

By Nancy Chan

A novel method for predicting the risk of prostate cancer recurrence following surgery that was developed by urologists at UCSF Medical Center has been validated in a recent study.

The new method is named the UCSF Cancer of the Prostate Risk Assessment (CAPRA).  It is a risk stratification index that produces an easily-calculated score from 0 to 10 to predict the likelihood that men will experience a prostate-specific antigen (PSA) recurrence after surgery.  Other existing risk-prediction tools, while offering comparable accuracy, have limitations, according to Matthew Cooperberg, MD, MPH, senior resident in urology at UCSF and lead author of the study.

“The accuracy and simplicity of this index will likely be of significant benefit for prostate cancer research and clinical practice,” said Cooperberg. “The goal was to devise a scoring system that would perform as well as the best available instruments for prediction of biochemical recurrence after prostate surgery, yet would be easier to calculate.”

The multi-institutional study appears in the November 15, 2006 issue of Cancer.

Prostate cancer is the most common non-skin cancer in the United States with more than 230,000 new cases diagnosed annually. It is the third leading cause of cancer deaths among men after lung and colorectal cancer. 

At the time of diagnosis, risk classification for patients based on disease characteristics such as the PSA level and Gleason grade (a pathologist’s measure of how aggressive tumor cells appear microscopically) helps identify who should be treated immediately and at what level of intensity, and who may be a candidate for a trial of active surveillance (i.e., deferred treatment with careful monitoring of PSA and other parameters).

In initial development tests that used the community practice-based Cancer of the Prostate Strategic Urological Research Endeavor (CaPSURE) registry, the CAPRA score performed as well as the best available risk prediction systems based on a number of preoperative variables, including age, PSA, Gleason grade, tumor stage, and percent of biopsy cores positive, according to Cooperberg.

“Using CAPRA, with its straightforward 0 to 10 scoring system, we could easily determine risk of recurrence based on these variables without a calculator, which is a major advantage over existing instruments,” said Cooperberg.  “Knowing the score allows us to help counsel patients regarding treatment options.”

Validation studies to confirm the accuracy of the CAPRA score were conducted over the past year using the Shared Equal Access Regional Cancer Hospital (SEARCH), a large, socio-demographically diverse cohort of 2,096 patients from 1988 to 2004 with localized prostate cancer who had undergone prostate cancer surgery at four Veterans Affairs medical centers and one active military hospital.

Of the more than 2,000 patients enrolled in the database, 1,309 were eligible and were included in the validation analyses.  Of the eligible patients, 336 (26 percent) experienced prostate cancer recurrence after surgery.

“As the CAPRA scores increased, we found that there were consistent increases in rates of adverse pathological outcomes such as extracapsular extension or seminal vesicle invasion, as well as increased likelihood of PSA recurrence after surgery,” Cooperberg said.

Future studies will assess the performance of the CAPRA score among patients undergoing radiation and other non-surgical treatments, and will test the performance of the score in predicting other outcomes such as progression to metastatic disease.

Co-authors of the study were Stephen J. Freedland, MD, Duke University; David J. Pasta, PhD, and Eric P. Elkin, MPH, UCSF; Joseph C. Presti, Jr., MD, Stanford University School of Medicine and Veterans Affairs Medical Center; Christopher L. Amling, MD, San Diego Naval Medical Center; Martha K. Terris, MD, Veterans Affairs Medical Center and Medical College of Georgia, Augusta, GA; William J. Aronson, MD, Veterans Affairs Center Greater Los Angeles Healthcare System and UCLA School of Medicine; Christopher Kane, MD, UCSF and Veterans Affairs Medical Center, San Francisco; and Peter R. Carroll, MD, UCSF.

The study was supported by a National Institutes of Health Specialized Program of Research Excellence grant; the Department of Veterans Affairs; the Georgia Cancer Coalition; a Center for Prostate Disease Research grant from the United States Army Medical Research and Material Command; the Department of Defense, Prostate Cancer Program; and the American Foundation for Urological Disease/American Urological Association Education and Research Scholarship Award and the Prostate Cancer Foundation. The development of the CAPRA score using CaPSURE data was also supported by TAP Pharmaceutical Products, Inc., which funds the CaPSURE project.

UCSF is a leading university that advances health worldwide by conducting advanced biomedical research, educating graduate students in the life sciences and health professions, and providing complex patient care.