Inquiring minds want to know: Why isn't PSMA PET used in men with low-risk prostate cancer?

(Editor’s note: I am often asked why PSMA (Prostate-specific Membrane Antigen) PET scans are not used on men with low-risk Gleason 6 cancers. PSMA PET, a nuclear test, is supposed to display any prostate cancer cells like an Xmas tree light in a dark room. It’s supposed to be the best thing in prostate cancer care since PSA testing and the prostate needle biopsy gun. To us guys with low-risk prostate cancer, it would seem to be a slam-dunk to tell us whether we have those cells so we can skip biopsies. I do know some guys who have wrangled PSMA tests because they were diagnosed with Gleason 6 but had sky-high PSAs, like 15 or above.

The issue of who qualifies for PSMA was put to The Radiology Report from Dr. Antonio Westphalen, of the University of Washington. Spoiler alert: You may not like the answer.

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Question: For patients currently on active surveillance, what are the prospects for the use of a PSMA PET scan as a location detection means of prostate cancer in the prostate, the results of which could be used to guide follow-up biopsies in lieu of a secondary or further random ultrasound-guided biopsy?

The Bub Man

(Diagnosed 12/23 with Gleason 3+3, Decipher test result at 28% (low risk), no lesions found on prostate MRI, PSA density 0.19, PSA 6.5.)

Dr. Antonio Westphalen:

It is essential to exercise caution when considering the utilization of PSMA PET in the management of prostate cancer for patients under active surveillance (AS). While PSMA PET has been FDA-approved for patients with treated high-risk prostate cancer to detect metastatic disease, its application in AS remains investigational and controversial.

One significant concern is the lack of substantial data to support its use in this context. Studies like the PRIMARY and PASPoRT trials suggest that PSMA PET can enhance the detection of tumors with a Gleason score of 3+4 or higher. However, the number of patients that must undergo PSMA PET to identify one such tumor is relatively high, indicating that it may not be the most efficient approach for patients in active surveillance.

Furthermore, PSMA PET is not widely available and can be costly, which raises practical concerns. The detection of abnormal foci with PSMA PET does not eliminate the need for a biopsy; it merely guides the biopsy process.

Consequently, instead of avoiding biopsies, PSMA PET would entail scanning many patients, biopsying all with positive findings, but only a few would ultimately benefit. In addition to potentially causing unnecessary biopsies, these false-positive results could also increase patient anxiety.

Additionally, the true impact of "missing" these tumors, which are often detected during routine AS and within the window for effective treatment, is uncertain. Therefore, PSMA PET may not significantly impact oncologic outcomes in these patients, and routine active surveillance appears to be adequate for monitoring those with tumors undetected by MRI without the need for additional imaging procedures.

In addition to the points raised earlier, it's important to emphasize that while PSMA PET could guide the biopsy process, it does not necessarily eliminate the need for a systematic biopsy in patients under active surveillance.

As of now, the data available is limited, and the role of PSMA PET in completely replacing systematic biopsies remains uncertain. Given the lack of comprehensive evidence, it is crucial to exercise prudence and consider that, at this point, PSMA PET should complement rather than replace systematic biopsies in AS patients. Further research is needed to better understand the true benefits and limitations of PSMA PET in this context before making it a standard practice in the management of prostate cancer under active surveillance.

Dr. Antonio Westphalen is the Section Chief of abdominal imaging at the University of Washington and UW professor of radiology. Dr. Westphalen’s research interests are centered on the use of advanced imaging technologies to diagnose and treat patients with prostate cancer.

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Here’s an earlier post on PSMA PET:

Reminder: Survey focusing on how prostate cancer impacts partners

By Howard Wolinsky

Prostate cancer is a couple’s disease.

Whatever your diagnosis—from very low-risk to very high-risk—your spouse, partner, significant other, etc. is impacted. In the case of Active Surveillance, your partner’s perspective can make or break the decision to be surveilled vs. treated.

EU-ProPer partners’ study

Antwerp-based Europa Uoma, a European advocacy organization for men with prostate cancer and their partners, representing 26 national patients’ groups, has done excellent research surveying men with prostate cancer. Now they are conducting an anonymous survey in Europe and beyond to learn about the experiences of partners of men with prostate cancer and the physical and psychological burdens the disease imposes on them.

Europa Uomo Chairman Guenther Carl said that the study builds on the knowledge gained from previous Europa Uomo studies about patients’ quality of life after treatment (the EUPROMS studies).

“Our EUPROMS surveys have gone some way to identify the burden of prostate cancer on the daily lives of affected men,” he said. “But we also know from our own experience that the effect on partners and caregivers can be considerable. If we can find out what would really help partners, it could have a significant impact on the type of support provided after diagnosis.”

He said the survey will help define unmet needs and provide an agenda for action.

The study, named EU-PROPER (Europa Uomo Prostate Cancer Partners in Europe Research), is available online in 17 languages. Pick your favorite.

So far, 600 partners have responded. Europa Uomo needs about 1,000 responses by year’s end.

Go to euproper.org to complete the survey.

A word from a subscriber

“I want to thank you for your labors in helping to lead the charge in pointing men toward solid prostate cancer information. I have been truly impressed by the volume and quality of your work.” Robert Sloan, DDS, Newport Beach, California.