Free PSA & Biochemical Recurrence

[pjoshea13]

New study below [1].

I doubt that many in the group who know their PSA level also know their percent free PSA [%fPSA].

Some might remember their %fPSA before diagnosis. A %fPSA <25 meant that there was a high risk of PCa. With a high %fPSA, one might skip the biopsy.

However, in the setting of biochemical recurrence, a %fPSA > 15 "after RP is an indicator of a more aggressive disease. Unlike in the diagnostic setting, a higher %fPSA portends a worse clinical outcome."

Does this mean that PSA in the free form promotes progression? Why does the reverse seem to be true before diagnosis? Curious.

-Patrick

[1] pubmed.ncbi.nlm.nih.gov/320...

J Urol

, 101097JU0000000000000808 2020 Feb 18[Online ahead of print]

A High Percent-Free PSA in the Setting of Biochemical Recurrence After Radical Prostatectomy Is Associated With Poorer Outcomes: A Validation Study Using Prospectively Collected Biobank Specimens

Dixon T S Woon 1 , Jaime O Herrera-Cáceres 1 , Hanan Goldberg 1 , Hina Shiakh 1 , Emily Whelan 1 , Gregory Nason 1 , Khaled Ajib 1 , Guan Hee Tan 1 , Thenappan Chandrasekar 1 , Omar Alhunaidi 1 , Antonio Finelli 1 , Alexandre Zlotta 1 , Alejandro Berlin 1 , Eleftherios Diamantis 2 , Neil Fleshner 1

Affiliations collapse

Affiliations

1 Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.

2 Mount Sinai Hospital, Department of Clinical Biochemistry, Toronto, Ontario, Canada.

PMID: 32068483 DOI: 10.1097/JU.0000000000000808

Abstract

Purpose: The role of percent-free PSA (%fPSA) in patients who have undergone radical prostatectomy (RP) and subsequently relapsed is unclear. We previously conducted two retrospective studies and found %fPSA ≥15 in the setting of biochemical recurrence (BCR) confers more aggressive disease. To validate that, we propose to use biobank specimens collected prospectively when patients were first diagnosed with BCR.

Materials and method: Biobank specimens of patients with undetectable PSA after RP and then develop BCR(PSA ≥0.1) were analyzed for %fPSA. Patients were stratified according to the %fPSA cut-off of 15%. Univariable and multivariable logistic regression analysis was performed to predict covariates associated with a higher %fPSA. Cox proportional hazard models were performed to evaluate the prognostic effect of %fPSA on androgen deprivation therapy (ADT) free survival, metastasis-free survival, castrate resistant (CRPC) free survival, cancer-specific (CSS) survival.

Results: 154 men were included in the study, of which 126 (82%) had %fPSA<15 and 28 (18%) had %fPSA≥15. Median follow up for %fPSA<15 and %fPSA≥15 was 75 and 69 months, respectively. Patients with %fPSA≥15 had increased hazard of receiving ADT (25% vs. 43%, adjusted HR 2.40 [95% CI 1.12-5.11]), developing metastatic disease (7.9% vs. 21%, adjusted HR 4.10 [95% CI 1.11-15.2]), and developing CRPC(4.0% vs. 14%, unadjusted HR 4.14 [95% CI 1.11-15.5]).

Conclusions: Patients with %fPSA≥15 were started on ADT earlier, and they progressed to CRPC and metastatic stage earlier. %fPSA of ≥15 in the setting of BCR after RP is an indicator of a more aggressive disease. Unlike in the diagnostic setting, a higher %fPSA portends a worse clinical outcome.

[LowT]

Does anyone know if it is possible to do %fPSA for results less than 0.1, the value this paper used? And if so, how low can you go? I would expect dealing with uPSAs it becomes more difficult if not impossible and the accuracy or reproducibility becomes much less the lower the uPSA.

[Hidden]

I have run across earlier publications concluding the same. Post RP, the higher the freePSA% the more aggressive the disease.

This is an informative but late-warning (if any at all) marker, due the detection capability of freePSA tests.

For the Roche cobas Elecsys equipment and assays:

"Limits and ranges

Measuring range

0.010‑50.00 ng/mL (defined by the lower detection limit and the maximum

of the master curve). Values below the detection limit are reported as

< 0.010 ng/mL. Values above the measuring range are reported as

> 50.00 ng/mL.

Lower limits of measurement

Lower detection limit of the test

Lower detection limit: ≤ 0.01 ng/mL"

labogids.sintmaria.be/sites...

This means that for a sensible assessment of the free to total ratio the latter shall be well higher to 0.1.

[PhilipSZacarias]

Very interesting. Worth investigating further. Phil