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2015 AUA Opko Health's 4Kscore Session Highlights

#AUA15 - Screening for lethal prostate cancer using PSA and related blood biomarkers - Session Highlights

2015 AUA
Published: 17 May 2015

NEW ORLEANS, LA USA (UroToday.com) - Dr. Hans Liljia provided convincing arguments on the roles of PSA and related kallikrein markers (4Kscore) for screening for lethal prostate cancer.

In ERSPC study, screening was shown to reduce death from prostate cancer. However, benefits over harms from over-diagnosis remain clear. As such, there is a need to improve efficacy of screening (risk stratification for whom to screen and risk stratification for whom to biopsy). Who to screen is not the same as who to biopsy. Additional blood markers are needed to improve specificity in discrimination of lethal cancer versus no cancer.

Dr. Liljia then showed the efficacy of PSA-based screening. He showed that PSA at age 60 is a strong predictor of risk of distant metastasis. 90% of prostate-cancer deaths occur in men with PSA in top quartile (PSA > 1.9ng/ml). Men with PSA below median (< 1 ng/ml) are unlikely to have metastasis or die from cancer. Similar findings are seen in men age 45-49 and men 50-54 where men in the top 10% and top 25% have a high risk of metastasis and death from prostate cancer while men below the median PSA are unlikely to.

Based on these results, Dr. Liljia proposes risk stratification for screening men at age 60. Men with a PSA < 1ng/mL (median PSA) could be exempted from subsequent screening. He recommends a discussion between physician and patient to continue screening in men with PSA 1-2ng/mL. Men with PSA 2 ng/mL should continue to be screened as the number needed to screen to prevent a death (NNS) = 23 and number needed to diagnose (NND) = 6 over 15 years follow-up.

He emphasized that PSA is a very sensitive marker for lethal disease. However, the main problem with it is specificity as most patients with elevated PSA do not have prostate cancer. PSA is an excellent methodology to risk-stratify patients for screening but a poor methodology to decide to biopsy. Another methodology is required to increase specificity and to reduce over-diagnosis of clinically indolent prostate cancer.

He also discussed studies of a panel based on 4K-Score in blood (total PSA, free PSA, Intact PSA, hK2). This is an algorithm that incorporates levels of each of these markers, along with age, to predict the probability of finding any grade cancer or high-grade (Gleason 7-10) cancer on biopsy. He showed that with this, specificity is markedly improved. He showed data that up to 57% of patients may be spared from prostate biopsy in patients with elevated PSA > 3 when risk of cancer is set at > 20% on 4K score.

A risk-stratified approach is needed first to screen patients and then to biopsy patients. PSA and 4K score are both important elements of this approach. In men with modestly elevated PSA (> 2ng/ml), the 4K score can be used as a reflex test to better identify the need for biopsy.

Presented by Hans Liljia, MD, PhD at the American Urological Association (AUA) Annual Meeting - May 15 - 19, 2015 - New Orleans, LA USA

Memorial Sloan Kettering Cancer Center, New York, NY USA

Reported by Nikhil Waingankar, medical writer for UroToday.com