Researchers from Duke University have reported that a prostate specific antigen (PSA) cutoff of 1.5 ng/ml is more predictive of prostate cancer than the median of 0.7 ng/ml. The details of this study were published in the March 2010 issue of the Journal of Urology.[1]

PSA screening is usually recommended to begin at age 50 years, unless there is a family history (in which, case earlier screening is recommended). There is very little published data on PSA screening of men in the general population before age 50 years. As well, there has been very little data on the risk of prostate cancer in African-American males. Researchers from the UK have previously reported the results of testing for PSA in 442 unselected men between the ages of 45 and 50 years. The reported that 54 (12%) had an elevated PSA using an age-related threshold of 1.5 ng/ml; there were 10 cases (2.3%) of prostate cancer detected.

Researchers involved in the current study evaluated PSA levels in 3,530 African-American and 6,118 White men 50 years of age or younger with PSA levels of 4 ng/ml or lower at first screening. The median PSA level for this group of young men was 0.7 ng/ml. They divided these men into four groups by initial PSA levels:

• to 0.6
• 0.7 to1.4
• 1.5 to 2.4
• 2.5 to 4.0

These authors reported: “[African-American] and [W]hite men with initial prostate specific antigen in the 1.5 to 2.4 ng/ml range had a 9.3 and 6.7-fold increase in the age adjusted prostate cancer RR, respectively. At up to 9 years of followup initial prostate specific antigen of 1.5 ng/ml or greater was associated with gradually increased detection at followup in [African-American]  and [W]hite men.”

Comments: These data suggest that a higher PSA level of 1.5 ng/ml may be a more appropriate cutoff for younger African-American and White men for diagnostic evaluation of prostate cancer. This is the same level adopted by the British study. However, it must be kept in mind that there is no level of PSA with high sensitivity or specificity for predicting prostate cancer.

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