Gerald Andriole, MD presents a historical perspective on risk assessment workflow in patients suspected of having prostate cancer, and discusses how pre-biopsy biomarker tests can address clinical challenges and unmet needs.
Dr. Gerald Andriole: Hi, I'm Gerald Andriole, I'm a Professor of Urology at Johns Hopkins and the Director of the Brady Urological Institute in the National Capital Region in Washington, DC.
Well, PSA and MRI are often very helpful for patients to determine whether they harbor prostate cancer or are at risk for the future development of prostate cancer. But the problem is, they're not perfect and they suffer from both overestimating the risk of prostate cancer in some patients and totally missing the presence of prostate cancer in other patients. So, for example, to speak about PSA, the majority of men who have an elevated PSA do not have significant prostate cancer; they're much more likely, at a population level, to have BPH to explain the elevated PSA. And to just comment on MRI very briefly, yes, MRI will identify many of the significant prostate cancers in a given man's prostate, but it has an unacceptably high miss rate for the most significant prostate cancers, and that can be as high as 25%; so, it may be falsely negative in about a quarter of the patients who actually harbor prostate cancer. So clearly, our early detection strategies which, until now, had relied for the most part on PSA and more recently MRI, notwithstanding that they're better than what we used to have, which was nothing. They're far from perfect and we need to do a better job for our patients.
The estimates are that more than a million men annually in the United States undergo a biopsy of their prostate. Now some of that is for patients, the first time their PSA was discovered to be elevated; for some of those patients, these are repeat biopsies, either because the urologist fears that the initial biopsy missed prostate cancer so he has to do it again; or the third main category are patients who are on active surveillance, in other words, they've already been discovered to have a low-risk small volume prostate cancer and they're being monitored by repeat biopsy. But notwithstanding the various indications for the biopsy, it's estimated that about a million men per year will undergo a prostate biopsy.
So, PSA is often elevated in men who don't have prostate cancer and that's because it's confounded by a benign enlargement of the prostate. And a strategy of doing an additional biomarker test before going to the expense of an MRI, which itself is not perfect, or to the expense and the potential morbidity of a biopsy; introducing biomarker testing prior to the first biopsy has been shown to make PSA screening more effective in the sense that with use of certain biomarkers, and I'll pick on 4K as an example, screening studies such as the PLCO test, a study in the United States, or the Protect study in the United Kingdom, has shown that you can safely avoid a negative biopsy in up to 35 to 40% of the men whose PSA is elevated if you have performed a 4Kscore prior to performing the biopsy.