Dr. Mark Emberton is a Professor of Interventional Oncology at University College London.
Prostatepedia spoke with him about focal therapy for prostate cancer.
What is focal therapy for prostate cancer?
Dr. Emberton: Focal therapy is an attempt to improve the therapeutic ratio. It addresses the harms and benefits of treatment. In prostate cancer treatment, the harms are too great for the benefit to accrue.
We can’t improve the benefit very much, but we can certainly reduce the harms that we inflict on our patients. Nearly every patient who has been treated for prostate cancer will experience a reduction in quality of life because of the impact on his sexual function, continence, or rectal function.
Focal therapy attempts to address that by preserving tissue. We’ve managed to preserve tissue in all other cancer management: breast through lumpectomy, kidney through partial nephrectomy, liver through partial hepatectomy, and penile cancer through partial penectomy. Prostate is the last bastion. Until recently, all men had the prostatic equivalent of bilateral mastectomy. In other words, their whole prostate tissue was removed irrespective of tumor volume, location, or number. Everyone was treated the same. With focal therapy, we attempt to preserve tissue, which preserves function.
How do doctors determine if focal therapy is appropriate for a man?
Dr. Emberton: It’s not for everybody. At the moment, we do surveillance so that men with very low-risk disease have no treatment. We offer surgery to men with high-risk disease who’ve got extensive, high-burden tumors in the same way we manage, say, breast cancer. We might choose to watch an elderly woman with a small breast lump. We might choose to do a mastectomy on a young woman with very aggressive breast cancer. But the majority of women—currently 80%—can get away with a lumpectomy. This is enabled by the ability to identify tumors and determine location and volume.
That’s a very recent development in prostate cancer. Until very recently, we were treating all men blindly. Since Hugh Hampton Young did his first prostatectomy at Johns Hopkins about 100 years ago, we’ve been treating prostate cancer without knowledge of tumor location.
What is the role of imaging?
Dr. Emberton: The new trick in town is that we can see the prostate cancer with MRI. If we can see it, we can direct needles at it. If we can direct needles at it, we can direct energy at it. We can zap the tumor rather than having to remove the whole prostate. We can have a much more nuanced approach now. Instead of treating all men the same, we can now stratify men by risk with great precision by biopsying them differently depending on where the tumor is and then allocating treatment depending on the risk stratification that has been assessed. If a man has one millimeter of Gleason 4+3, most of us would not treat. I certainly wouldn’t. If he has extensive bilateral disease, I would offer whole-gland treatment in the form of surgery or radiation therapy. If he has got a 0.5 cc tumor in the right peripheral zone of the prostate, I see no reason why we shouldn’t offer a selective destruction of that tumor that preserves erections, ejaculation, and continence. We’re doing that today. We’re having conversations with men today that we couldn’t have had three to four years ago because we didn’t have the tools.
What about other advances in imaging?
Dr. Emberton: PSMA is very useful in staging men. It’s concordant with MRI and the prostate, but it doesn’t give us the spatial resolution that we would require to decide which part of the prostate to treat. The PSMA PET/CT will be positive on the left or the right side of the prostate, but will not give us any more information. It’s really useful in the high-risk man with whom you’re trying to rule out metastatic disease.
There are a variety of forms of focal therapy, correct?
Dr. Emberton: I think conceptually, it’s very clear. We offer men focal therapy when we can treat the tumor plus a margin and we think we can do so faithfully. But there are lots of ways to do it. Just like surgery, you can have an open, transperineal, laparoscopic, or robotic prostatectomy. In brachytherapy, high-dose rate (HDR), low-dose rate (LDR), CyberKnife, TrueBeam, protons, external beam, the principle is the same.
Yes, we have a few options with focal therapy, though not as many as surgeons and radiation therapists. We’re often accused of having a cornucopia of ways of treating. Actually, we don’t. We have heat (hot or cold) and we have electricity in the form of radio frequency or electroporation.