Lower PSA Biopsy Threshold Advised
It may be appropriate to drop cutpoint from 4.0 to 2.0-2.5 ng/mL in men younger than 50 years
Diagnostic PSA levels in men younger than 50 years are significantly lower than guidelines suggest, according to researchers.
In addition, the conventional PSA velocity (PSAV) biopsy threshold of 0.75 ng/mL per year or less may miss prostate cancer cases in these men. As a result of their findings, they advise using a PSA threshold of 2.0-2.5 ng/mL instead of 4.0 for biopsy in these men as well as lowering the PSAV biopsy threshold to 0.60 ng/mL per year or less.
Judd W. Moul, MD, and his colleagues at the Duke Prostate Center at Duke University Medical Center in Durham, N.C., examined data from 12,078 men, including 1,622 with prostate cancer. Based on the latest date for a PSA test, the men were divided into two groups: those younger than 50 (904 men) and those aged 50 years and older (11,174 men). The younger group had 40 cases of prostate cancer (4.4%) and the older group had 1,582 (14.2%). About one third of the younger men with cancer had a PSAV of 0.75 ng/mL per year or less and 38.5% had a PSA level below 4.0 ng/mL.
In the cancer patients, the younger group had a median PSA level of 1.3 ng/mL compared with 6.3 ng/mL in the older group, Dr. Moul's team reported in BJU International (2007; published online ahead of print).
For men younger than 50, the sensitivity and specificity for the traditional PSA biopsy threshold of
4.0 ng/mL was 61.3% and 97.7%, respectively. At a PSA threshold of 2.0 ng/mL, the sensitivity and specificity were 75% and 92.2%. If the PSA threshold was 2.5 ng/mL, the figures were 73.8% and 94.1%. For men aged 50 years and older, the sensitivity and specificity for a PSA threshold of 4.0 ng/mL was 71.3% and 85.2%, respectively. The sensitivity and specificity were 83.4% and 65.5% at a PSA threshold of 2.0 ng/mL and 81% and 72.7% at a threshold of 2.5 ng/mL.
In the younger cancer patients, the sensitivity and specificity for a PSAV threshold of 0.75 ng/mL per year was 66.7% and 86.3%, respectively. A PSAV of 0.2-0.6 ng/mL had a sensitivity and specificity of 71.4%-85.7% and 62.1%-83.7%, respectively.
For men aged 50 and older, the traditional PSAV threshold missed only 27.6% of the cancers and the PSA level threshold missed 29.3%. The positive predictive value for the traditional PSAV threshold was 41.2% for the older men and 20% for the younger men.
Using a PSA threshold of 2.5 ng/mL or higher and a PSAV threshold of 0.60 ng/mL per year or less in the younger-than-50 group detected another six cancer cases, the researchers said.