The Staging Guide Video Series | Transcription:
Hi, I'm Dr. Scholz, let's talk about prostate cancer. In this video we're going to cover focal therapy for prostate cancer. That means treating a section of the prostate rather than the whole gland. Many people aren't aware of the fact that standard treatments like radiation don't focus on the tumor specifically, they focus on the borders of the prostate. Historically, we haven't had the technology to define exactly where the cancer is located, and so for safety reasons and for thoroughness, the gland is targeted rather than the tumor. When we talk about focal therapy, we are talking about treating a section of the gland where the tumor is located.
The primary reason to consider focal therapy is to reduce side effects. When the whole prostate is targeted, with radiation or surgery, the incidence of impotence, urinary incontinence, urinary bother, and rectal damage is substantial; even in the hands of the best experts. The idea of doing a focal treatment to a section of the gland to reduce the risk of side effects is a very attractive proposition.
When we're talking about focal therapy, we're talking about a lot of different ways to destroy a section of the prostate. We could use radiation, seed implant radiation or beam radiation, which is called either Cyberknife or SBRT; laser treatments, freezing the gland, high intensity focused ultrasound, radio-frequency ablation. There are a number of different ways that doctors can treat a section of the gland.
In my view as an expert in referring patients, the quality or the expertise of the doctor doing the treatment, the experience, is probably more important than the type of treatment being used. There are certain advantages and disadvantages. For example, take cryotherapy. Cryotherapy involves inserting a probe into the tumor area, circulating liquid argon, creating an expanding ice ball where the cancer is, circulating warm water to thaw that ice ball, refreeze, thaw on a second cycle, and remove the probe. But when you freeze a section of the body, the body fights that and tries to compensate for that freezing, and there's a transition zone that is not completely frozen. For that reason, cryotherapists have to freeze a larger margin around the tumor, to make sure that they kill the tumor.
Laser treatments on the other hand, and this is not to speak as an advantage or disadvantage, has a very sharp line of demarcation between the treatment area and the untreated area. So, they don't have to treat as large of an area, but there may be a greater risk of not getting all the tumor. So, all of these different methodologies require special skills and training, and it's not clear that any one is superior to the other. But as a general, overall view, the idea of just treating a section of the prostate is very attractive, and a number of centers are springing up across the country and around the world to give this type of treatment.
So, clearly not all patients would be eligible for focal therapy. Patients that have bilateral tumors for example, would require such a large area of the prostate to be treated to ensure a cure, that there would be little of any advantage for leaving a small rim of gland. So the type of patients that can undergo focal therapy are those that have the cancer limited to one side of the gland. The other critical component is for the tumor to be easily visualized with imaging, either color Doppler or multiparametric MRI. The doctors use an imaging tool to determine where to treat. Some tumors which are detected by random biopsy, for example, may be small and even invisible on an imaging study. Such patients won't be good candidates for focal therapy, because the doctors can't see exactly where to treat. So the two requirements, to review then, are imaging visibility on a scan and unilaterality, that is, tumor confined to one side of the gland.
What specifically are the drawbacks for focal therapy? Well, it's new. And many of the doctors that are offering focal therapy are still in their learning curves. They're still learning who to treat, how much to treat, and so, without good quality control it's difficult to know where to go and who to trust. Some of the treatments that we've talked about will be covered by insurance, but others are not. So, cost can be an issue. Sometimes tens of thousands of dollars, whereas if you went through a standard IMRT or seed implant, that would be covered 100% by your insurance. Third problem with focal therapy; because only a portion of the gland is treated, or in other words, a section of the gland is untreated, patients will have to be monitored the rest of their life for the possibility of a new cancer showing up in the untreated gland. Patients who have focal therapy are going to need to be monitored with active surveillance, just like a patient who pursues active surveillance as a primary therapy.
Lastly, the concern about cure rates with focal therapy is that, if the whole prostate is treated, like with standard radiation treatment for example, how can those patients not have a higher cure rate than someone who only has a section treated? I think there's some truth to those arguments, but with modern imaging and using a generous margin of treatment area around the tumor, cure rates with focal therapy are going to be very, very high. Undoubtedly, the side effects will also be fewer and, as a result, I believe that focal therapy is going to be a growing area, a very popular type of treatment in the future. The main problem of course being that this is very new and people are still in their learning curves.
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