"We're all very aware of the impact that prostate-specific antigen [PSA] has had on screening for prostate cancer. What's underappreciated is how the biopsy technique pivoted at about the same time," says Adam S. Kibel, MD.
Urology Times® is celebrating its 50th anniversary in 2022. To mark the occasion, we are highlighting 50 of the top innovations and developments that have transformed the field of urology over the past 50 years. In this installment, Adam S. Kibel, MD, discusses the development of transrectal ultrasound-guided prostate biopsy and how prostate biopsy has continued to evolve over the years. Kibel is chief of urology and the Elliott Carr Cutler Professor of Urology at Harvard Medical School in Boston, Massachusetts.
Please provide an overview of the development of transrectal ultrasound-guided prostate biopsy.
We're all very aware of the impact that prostate-specific antigen [PSA] has had on screening for prostate cancer. What's underappreciated is how the biopsy technique pivoted at about the same time. It used to be that a large-bore needle would be used to identify a nodule in the prostate and they would take that transaxial biopsy—that's where you got sort of a core inside a core. It caused significant discomfort to the patient, and we had no way of imaging where any cancer was. Then, transrectal ultrasound was introduced, and people began to realize that they could identify the prostate very easily, and, at least initially, they thought they could identify lesions and take biopsies from those lesions using a transrectal probe. There is also minimal pain sensation with this method.
What people rapidly realized is that ultrasound was very good at identifying the prostate, but not necessarily identifying lesions within the prostate. The end result is we had a tool in which we could do systematic biopsies of the prostate, in the office with minimal discomfort, and pairing that with PSA screening dramatically changed our ability to diagnose the disease. Before that, we had no real way of identifying the prostate besides using a finger, and therefore, it was very hard to accurately guide a needle into the prostate and get adequate tissue in order to identify whether it was cancer or not. It was revolutionary; that's the only way to describe it.
What makes TRUS prostate biopsy an innovation in urology?
In the past, urologists had to conduct a rectal exam, identify where there was a nodule, and then use various techniques with their finger in order to guide the needle to take a series of biopsies from the prostate. That's inaccurate. The ultrasound is not very good at identifying lesions in the prostate that could harbor cancer—at least back in the 1980s and 1990s, it wasn't. But it could identify where the prostate was, and it could give you an idea of the various zones of the prostate, so you could orient your needles in order to hit the peripheral zone where the vast majority of the tumors were actually located. Prior to this, we really had no way of targeting the prostate, let alone targeting lesions, so this was a huge step forward in that we had a simple, reproducible, accurate way of identifying prostate anatomy. So we could put a needle in reproducible areas of the prostate and determine whether the patient had cancer.
Please provide an overview of transperineal biopsy.
Transperineal biopsies have been around for a long time. The initial issue was that you couldn't identify where the prostate was. Using your finger to guide the needle was much easier than trying to put it through the skin, where you're a long way away from the prostate. There was increased use of transperineal MRI-guided biopsies. When someone's in an MRI machine, the easiest thing to do is to put the needle through the skin into the lesion, and so people became very comfortable with the idea that you could go ahead and identify a cancer and put a needle into the area between the rectum and the testicles. At the same time, there was a series of patients who would have a very elevated PSA and we couldn't find any cancer. There were many people that adopted the concept of doing a saturation biopsy, where they would put needles in the prostate every half a centimeter to a centimeter throughout the entire prostate, so essentially sampling the entire gland, as opposed to transrectal ultrasound, where you're orienting these laterally into the peripheral zone.
The problem with all of those approaches is that they hurt. There's a lot of pain and discomfort. A lot of people didn't want to use transperineal approaches because of fear of causing the patient pain. What changed is 2 things. First of all, there was an increased incidence of infections, primarily due to bacteria that were resistant to antibiotics. Obviously, the rectum is not as clean as the skin and is harder to clean. You can clean the skin before you do a biopsy, but you can't really clean the rectum. The second thing was the appreciation, using MRI, of how you could identify lesions within the prostate and potentially target them. So then the more modern transperineal approach, which has been under evolution for the past 5 years or so, is to use an ultrasound transrectally in order to identify where the prostate is, but put the needle in transperineally, similar to what you would do with an MRI-guided biopsy or a saturation biopsy in the operating room. It's addressing an underlying problem that we had with transrectal ultrasound-guided biopsies, which is the increased risk of infection and using technology and an understanding of anatomy that evolved over time, due to both MRI biopsies, saturation biopsies, and transrectal ultrasound-guided biopsies to allow us to do a better job.
Are you currently performing transperineal biopsies?
We are doing some in the clinic. You have to use a lot of local medicine; it's a much more sensitive part of the body. It is associated with a slightly decreased risk of infection. But it does have other side effects such as an increased risk of retention. So you have to balance those 2 things when you're doing the biopsy. Because of the discomfort, for some patients, the biopsy has to be performed in the operating room, or under IV sedation. As a result, we're in evolution toward those transperineal approaches. But in point of fact, I think the transrectal approach is still useful in the right patient. When we talk to patients, we discuss the pros and cons of both approaches, and then decide which way to proceed.
What future innovations do you foresee when it comes to prostate biopsy?
Vis a vis the transperineal approach, as we get better and better at doing it, we're going to be able to do it better and better in the clinic, and I think there will be fewer cases that will need to be done in the operating room. There will always be some biopsies that are done in the operating room. Even if you're doing it transrectally, there are some patients who just can't tolerate it, and so I don't think that's going to go away completely. But as we have a better understanding of which patients can tolerate it, we'll be able to bring more and more of them into the clinic. I think there'll be more and more recognition of which patients we can safely do transrectally and which ones we really have to do transperineally. As people start to use different instruments, they get a better feel for, in the real world as opposed to in the papers, what actually is going to be useful in routine clinical practice. I think we'll get a better idea of which patients we need to biopsy. We talked about the side effects of biopsy, but the ultimate way to have fewer side effects from biopsying patients is to not biopsy them. Back when I first finished my training, there was a knee jerk approach of just biopsying everybody with an elevated PSA. That's gone away, for good reasons. We need to contemplate if every patient needs a biopsy, particularly patients who have negative MRIs, normal biomarkers, and in particular, patients who've had prior biopsies. I'm not saying I know who should and shouldn't get a biopsy, but I do know, I see some patients and I think, can we avoid biopsying this patient? There are a lot of interesting things going on with ultrasound right now, where the ultrasounds are able to provide potential targets. MRI continues to evolve rapidly, which will also provide us with targets. And I think one of the questions we're wrestling with is, can we actually just biopsy the target and not the whole prostate, which again, would decrease complication rates because let's face it, the fewer needles you need to put into an organ, probably the safer it is.