Coming soon? — Beckman Coulter’s “Prostate Health Index”
Posted Apr 20 2010 12:00am
At the annual meeting of the European Association for Urology (which ends today in Barcelona), there was a sponsored symposium entitled, “Prostate Health Index (phi) – A simple blood test significantly improves on PSA in the selection of men for biopsy and is a major advance in prostate cancer risk assessment.” The symposium was sponsored by Beckman Coulter.
Serum Prostate Health Index (phi) significantly increases specificity when selecting men for biopsy
Implementation of the Prostate Health Index (phi) in a prostate cancer risk assessment tool
Predicting an unfavorable outcome in men enrolled in active surveillance for prostate cancer
Additional information suggests that, “Serum Beckman Coulter phi is a multivariate index incorporating PSA, free PSA and [-2]proPSA concentrations into a single result to estimate the probability of cancer in men aged 50 and older with total PSA in the 2.0-10.0 ng/ml range and a non-suspicious DRE. [-2]proPSA is a novel serum marker strongly associated with prostate cancer and delivers added specificity to PSA. As a result, phi contributes to significantly reduce the number of negative biopsies resulting from suspicious PSA or %free PSA results.”
According to a media release from the American Association for Cancer Research (AACR) issued yesterday, “Researchers at Johns Hopkins have evaluated a simple, more specific blood test that identifies patients undergoing proactive surveillance for low-grade, low-stage, non-palpable prostate cancer who would eventually require treatment.” The media release refers to data presented at the AACR’s annual meeting, currently being held in Washington, DC. Additional information about the data presented at the AACR meeting is also available in a report from HealthDay .
“Finding biomarkers that can predict future unfavorable biopsy conversion will help us to identify men with prostate cancer who may or may not need treatment,” states Dr. Robert Veltri of Johns Hopkins the senior author of the presentation at the AACR meeting. And the media release goes on to discuss data from 71 patients who were enrolled in the Johns Hopkins active surveillance patient cohort.
Using the novel application of the Prostate Health Index immunoassay and DNA content measurements performed by image analysis, Veltri and colleagues tested 71 patients enrolled in the Johns Hopkins Hospital Proactive Surveillance Program. Apparently they were able to show that the Prostate Health Index “was higher in men who were determined to have unfavorable biopsies,” according to Veltri. They also showed that “DNA content in biopsy tissue from the prostate gland next to the cancer area and area itself were significant predictors of a change from a favorable to an unfavorable biopsy in the Proactive Surveillance patients.”
What, you may well ask, is the Prostate Health Index? Apparently it is some form of index based on calculations that correlate data from three different PSA levels total serum PSA, free PSA, and pro-PSA and the estimated prostate volume.
Suggestions appear to be being made that the Prostate Health Index or phi (perhaps pronounced as fi?) is capable of selectively identifying men at higher risk for progressive prostate cancer, who therefore are in need of treatment compared to men with truly indolent disease. However, since we have seen no data from any sort of large, randomized, prospective trial, we also get the impression that (at least to date) these suggestions look more like marketing than science! Now we happen to believe that marketing is an entirely respectable activity … when it is based on data that is available to the public. Unfortunately, to date, we haven’t seen any of the data that might suggest a clinical value for phi.
Now what we found even more interesting was some material in the HealthDay article. According to Dr. William Catalona, “the phi test is awaiting approval by the U.S. Food and Drug Administration and already is approved for use in Europe.” Furthermore, based on data from a study of 2,000 men in the Chicago area, “we found it to be more accurate than the tests now available, and it also seems to identify the more aggressive prostate cancers.”
Can we look forward to Dr. Catalona presenting these data at the AUA later this year? Apparently we can. Here is a link to the abstract . It is worth carefully noting the conclusion, which reads as follows: “We conclude that phi may add significant information regarding individual patient risk and may be used as an aid in patient management.” (The bold italics have been added for emphasis.) This seems like fair comment based on a study that didn’t follow any of the patients over time, so what we absolutely do not know is whether patients actually benefited, clinically, from having this test, or whether the test was actually able to project, with statistical accuracy, which patients really would go on to have progressive disease or indolent disease!
Based on this abstract and the small amount of other data available to date, it certainly appears that the Prostate Health Index can better correlate with the probability of a positive biopsy result than a PSA test or a free PSA test or perhaps even a proPSA test alone. However, a positive biopsy result is not necessarily an indication for “aggressive” prostate cancer by which we mean prostate cancer that will have clinically significant impact on the patient.
At this point in time, it would seem to The “New” Prostate Cancer InfoLink that there’s still a very long way to go before anyone should be claiming that the phi test can actually differentiate with accuracy between men with aggressive disease who definitively do need treatment and men with indolent disease who definitively do not need treatment. However, if Beckman Coulter can get the US FDA to approve this test, we have little doubt that it is going to be aggressively marketed. So far we have been unable to identify in which European country or countries the phi test has been approved … or exactly what it may have been approved for.