Urine test may detect aggressive prostate cancer, eliminate need for some biopsies
Key takeaways:
- MyProstateScore 2.0 showed high sensitivity for detecting aggressive prostate cancer without the need for a digital rectal examination.
- The test may help some men avoid unnecessary biopsies and MRIs.
A home urine test demonstrated high sensitivity for detection of aggressive prostate cancer, according to study findings.
The approach may help some men with lower risk avoid unnecessary biopsies, researchers concluded.
Prior research showed the test — MyProstateScore 2.0, or MPS2 — could identify Grade Group 2 or higher cancers; however, in those investigations, researchers obtained urine samples from men after they had undergone digital rectal examinations.
In the current study, Ganesh S. Palapattu, MD, FACS, George F. and Sandy G. Valassis professor and chair of the department of urology at University of Michigan Health, and colleagues evaluated the test in a cohort of 266 men (median PSA, 6.6 ng/mL; interquartile range, 4.9-9.1) who had not undergone digital rectal examinations prior to urine collection.
More than one-third (39%; n = 103) of men in the cohort had Grade Group 2 or higher on biopsy.
Investigators compared the performance of MPS2 to PSA testing and the Prostate Cancer Prevention Trial Risk Calculator (PCPTrc).
Results showed areas under the curve for detection of cancers with Grade Group 2 or higher 71%, 74% and 77% with MPS2 models, compared with 57% for PSA testing and 62% for PCPTrc.
Under a testing approach maintaining 92% sensitivity for Grade Group 2 or higher cancer in the general population, MPS2 testing would have prevented 36% to 42% of unnecessary biopsies.
Researchers also used mathematical modeling to determine how many men with previous negative biopsy would have avoided repeat biopsies. Rates ranged from 44% to 53% with MPS2, compared with only 2.6% using PCPTrc.
“This test has the ability to hone in and refine our focus on individuals at high risk for developing aggressive prostate cancer, and also allows us to provide reassurance and de-escalate surveillance for men unlikely to have high-risk prostate cancer,” Palapattu told Healio. “This has significant ramifications for cost, as well as for patient comfort and anxiety.”
Healio spoke with Palapattu about the current standards for predicting aggressive prostate cancer, the advantages the MPS2 test may offer and the next steps in research.
Healio: How do clinicians evaluate prostate cancer aggressiveness now?
Palapattu: One of the major problems in the area of prostate cancer at the moment is that of over-diagnosis and overtreatment. When a man is evaluated for potential prostate cancer, we typically do a PSA blood test. This can be very helpful for identifying men who are at risk for prostate cancer, but it’s far from perfect. There are a number of noncancerous reasons for PSA to be elevated, such as infection, inflammation, irritation and an enlarged prostate.
Use of PSA testing alone results in many prostate cancers being diagnosed. However, many of them are not harmful. As urologists, our goal is to identify cancers that are likely to be aggressive so we can focus treatment on those who need it and avoid harming those who don’t need it.
Part of prostate cancer diagnosis involves performing a prostate needle biopsy, typically preceded by a prostate MRI. MRIs are not perfect either — they miss perhaps 15% to 20% of aggressive prostate lesions. There also is variability in MRI geographic accessibility, types of MRI machines and individuals with expertise to read prostate MRIs. It’s a limited resource.
Healio: How did the MPS2 test come about and how does it predict prostate cancer aggressiveness?
Palapattu: This particular iteration built upon prior work that our group had done to evaluate this urine-based biomarker. This test is designed to identify those likely to harbor aggressive prostate cancer and, just as importantly, those who are highly unlikely to harbor aggressive prostate cancer.
The test we previously validated involved having the patient undergo a digital rectal exam in the office. The current assay builds on these findings and is able to be performed without a prior digital rectal exam. That opens the test to individuals who are calling their physician on the phone or using telehealth. Patients can do this test from home or go to a lab and deliver a urine sample. Specifically, it looks at 18 genes. Most of the 18 genes in this assay are prostate cancer-specific, and many are aggressive prostate cancer-specific. So, there’s a notable difference between this and PSA testing alone. PSA is prostate-specific, but it’s not prostate cancer-specific.
The MPS2 test is a molecular diagnostic test. With this assay, we’re able to generate a report that estimates the probability of a man having aggressive prostate cancer. Using that information, a health care provider — in concert with the patient — can decide whether additional testing needs to be performed.
If a patient has an elevated PSA that we believe is concerning, a negative MPS2 test has a 95% to 99% negative predictive value, meaning there’s a very high probability that it is correct — that is to say, that aggressive prostate cancer would not be detected on subsequent biopsy. This potentially enables us to avoid MRIs, which are costly, and also to avoid downstream biopsies. It also has an extraordinary sensitivity for detection of aggressive prostate cancer. When it’s positive, that indicates a very high likelihood of aggressive prostate cancer.
Healio: How did you study the efficacy of the test?
Palapattu: We had pre-collected urine samples from men who gave us samples prior to their biopsies. We also had the subsequent biopsy information available to us, and some patients had MRI results. We also had information on prostate volume, as well as family history and other pieces of clinical information. We used the assay on these samples in a way that no longer requires a digital rectal exam. We compared it with some existing biomarkers, such as PSA, as well as the PCPTrc.
Healio: What did you find?
Palapattu: The test has a very high sensitivity for diagnosing or predicting the probability of aggressive prostate cancer on subsequent biopsy. Just as importantly, it showed an ability to rule out those who are highly unlikely to have aggressive prostate cancer on biopsy.
Healio: What are the next steps in research?
Palapattu: Future studies will need to be done about how we can use this test for men who are already diagnosed with prostate cancer and were determined to be low risk. We want to see if this test can identify men who will subsequently develop more aggressive disease. We currently surveil men with low-risk disease every 6 months with a blood test. Then every year or every other year, they undergo biopsy or an MRI or both. These tests are costly and potentially uncomfortable. If we could limit those by introducing this very easy-to-use test, we could have an opportunity to revolutionize the way we manage men with low-risk prostate cancer on active surveillance. The vast majority of men who are diagnosed with prostate cancer in the United States have low-risk disease
References:
For more information:
Ganesh S. Palapattu, MD, FACS, can be reached at gpalapat@med.umich.edu.
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