Feb. 25, 2009 -- For the first time, researchers say they have developed a tool that can help predict a man's future risk of developing prostate cancer.
The personalized risk calculator combines prostate-specific antigen (PSA) test results with additional prostate cancer risk factors, including previous prostate biopsy results, family history of prostate cancer, and prostate size.
"Doctors use PSA to determine whether a man currently has prostate cancer. But the idea of using a combination of baseline PSA levels and specific, known risk factors to give a longer-term view about prostate cancer risk is a new concept that we hope will become part of standard practice," says researcher Monique Roobol, PhD, an epidemiologist in urologic oncology at Erasmus University Medical Center in Rotterdam, the Netherlands.
"Assessing future risk of prostate cancer is important for identifying men who are candidates for more frequent screening," she tells WebMD.
PSA and Prostate Cancer Risk
For the study, Roobol and colleagues examined the value of PSA combined with digital rectal exam findings, prostate size, previous prostate biopsy results, family history of prostate cancer, and age at diagnosis in predicting the future risk of prostate cancer among 5,176 men in the Netherlands. The men had an initial screening to assess all of these risk factors and a second screening four years later.
The researchers found that PSA level was the strongest predictor of future prostate cancer risk. Men with PSA levels of 1.5 or higher were seven times more likely to develop prostate cancer over the next four years than those men whose PSA scores were below that level.
Importantly, for any given PSA level, the other factors further modified this risk, Roobol says. A family history of prostate cancer elevated a man's future cancer risk, while a previous negative biopsy and increasing prostate size lowered risk.
For example, a man with a PSA of 1.3 and no previous negative biopsy, a positive family history, and a smaller-than-average prostate size had a 5% chance of developing prostate cancer within four years.
In contrast, a man with a previous negative biopsy, no family history, and a large prostate could have a PSA of up to 4.0 before he would have a 5% risk of prostate cancer within four years.
"This is a very sensitive method of integrating other factors besides PSA into prostate cancer screening and detection," says Howard M. Sandler, MD, a prostate cancer specialist at Cedars-Sinai Medical Center in Los Angeles.
Sandler moderated a press briefing to discuss the findings, which are being presented later this week at the Genitourinary Cancers Symposium in Orlando, Fla. He's an official with the symposium.
Urine Test for Aggressive Prostate Cancers
Also at the meeting, researchers reported that they have developed a urine test that may be able to help identify prostate cancers that are most likely to grow and spread quickly.
The experimental test is known as the T2:ERG urine test. It detects the fusion of two genes that are found in about half of prostate cancers and have been associated with more aggressive disease.
"There is an unmet need for tests that can determine which patients need aggressive treatment such as surgery to remove the prostate and those that can be managed conservatively with close monitoring for signs of tumor growth," says Jack Groskopf, PhD, of Gen-Probe Incorporated, the developer of the urine test.
Widespread use of PSA blood testing has resulted in high rates of early prostate cancer detection. The PSA test is not useful, however, for predicting which men have aggressive disease, he says.
Furthermore, the PSA test is associated with a high rate of false positives and unnecessary biopsies, Groskopf says.
Low False-Positive Rate
The new study involved 556 men scheduled for prostate biopsy. The biopsies showed that 226 of the men (41%) had prostate cancer.
The new urine test gave false-positive results to 15% of men that did not have prostate cancer. The comparable figure for PSA testing is 73%, according to data cited in the study.
Moreover, the urine test results correlated with criteria currently used to identify aggressive cancer at the time of biopsy, such as tumor grade and the amount of cancer found in the biopsy tissue.
"It was able to distinguish between significant and indolent cancers," Groskopf tells WebMD.
Prostate cancer is diagnosed in more than 186,320 Americans and claims more than 28,000 lives each year.