COMMENTARY

PSA Density: A Better Predictor of Prostate Cancer Risk?

Gerald Chodak, MD

Disclosures

August 01, 2017

Hello. I am Dr Gerald Chodak from Medscape. Today I want to talk about the role of prostate-specific antigen (PSA) density for improving detection of prostate cancer compared with PSA alone.

Jue and coworkers[1] reported on nearly 1300 men who were part of a prospective trial evaluating the 4Kscore. They estimated PSA density by performing a standard PSA test, performing an ultrasound, and then using the ellipsoid method for evaluating prostate volume. They divided the patients into three groups based on PSA [level]: < 4 ng/mL, 4-10 ng/mL, and > 10 ng/mL.

For men whose PSA [level] was < 4 ng/mL, density was not a very effective way of improving detection of the disease. However, for men with higher PSA values, they did find a better area under the curve (AUC) when density was compared with the standard PSA method. The problem was, it did not make much of an improvement. For example, when using PSA density of 0.05 ng/mL/cc, they found that 4% of significant cancers and 8% of the total number of cancers could be missed, while sparing about 15% of men from undergoing a prostate biopsy. The standard PSA density of 0.15 ng/mL/cc missed far too many cancers to be considered worthwhile.

They did find slightly better results if men had had a previously negative biopsy. There, the difference in the AUC between PSA alone and PSA density was the greatest. Whether it is good enough remains to be seen.

Ultimately, what we have here is a tradeoff. Is it worth doing the PSA density to decide whether a biopsy is needed to spare just 15% from having a biopsy while missing some 4%-8% of the cancers? That will be an ongoing discussion between the patient and the doctor.

For now, the bottom line is that in some cases, PSA density might be more useful than PSA alone. I do not think that the tradeoff of improvement in number of men saved from having a biopsy justifies missing 4%-8% of the cancers.

Time will tell. We will have to wait for other studies to further evaluate this. In the past, PSA density was not found to be very useful.[2] Here, the authors are saying [that] if you use a lower density value of 0.05 ng/mL/cc, you can get better results. The question is, are they good enough?

I look forward to your comments. Thank you.

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