Using Nomograms to Predict Prostate Cancer Risk

Johns Hopkins Health Alert

If you have just had a prostate-specific antigen (PSA) screening test, the words "Your PSA level is 4" are not particularly welcome. In general, the higher the PSA, the greater the likelihood cancer is present. So a score of 4 ng/mL is likely to sound warning bells for your doctor to order a biopsy, the results of which are used to help confirm or rule out the presence of prostate cancer.

Today, however, a growing number of doctors are questioning the value of using any single PSA value for all men. Instead, they consider the PSA result as just one of many pieces of information that can be used to help determine a man's risk of having prostate cancer that needs treatment.

PSA problems. Experts worry that a PSA screening cutoff of 4 ng/mL is not sufficiently sensitive. The term "sensitivity" describes how good a test is at not missing people who have a condition -- in this case, prostate cancer. This is referred to as a false negative. Many factors, such as benign prostatic hyperplasia (BPH), prostatic inflammation or even an ejaculation within 72 hours of a PSA test, can cause a false-positive result.

In the Prostate Cancer Prevention Trial, for example, 7 percent of men who had a PSA level of below 0.5 ng/mL had cancer, and about 12 percent of those cancers were high-grade, aggressive tumors with the potential to become life threatening; among men with a PSA of 3.1 to 4 ng/mL, 27 percent had cancer, and 25 percent of those were high grade. As a result of findings from this and other studies, many doctors now recommend lowering the threshold for a standard biopsy from 4 ng/mL to 2.6 ng/mL to pick up some of the men who were missed by using the higher threshold.

Of course, while lowering the threshold allows for the identification of more men with prostate cancer, it also means that even more men who don't have cancer or who have non-life-threatening disease will be flagged. Those with cancer may be subjected to medical procedures they may not need, especially if they are older and have other medical problems.

Using Nomograms to Predict Prostate Cancer Risk. One answer to these dilemmas may be to combine the PSA test results with additional information from other sources to more accurately diagnose prostate cancer and predict the risk of disease progression.

One method of predicting risk that is gaining popularity is the use of nomograms. A nomogram considers multiple weighted factors to calculate risk. For example, a nomogram that was developed using information from the Prostate Cancer Prevention Trial attempts to determine your risk of having biopsy-detectable prostate cancer based on information about your race, age, PSA level, family history of prostate cancer, digital rectal examination (DRE) results, whether you've had a biopsy in the past and whether you take finasteride (Proscar).?

Posted in Prostate Disorders on December 22, 2011

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Source: http://www.johnshopkinshealthalerts.com/alerts/prostate_disorders/PSA-screening_5965-1.html

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