What is focal therapy for localized prostate cancer?

For many years there have been two main approaches to managing localized prostate cancer.

The first is active surveillance or “watchful waiting.” In cases of older men or low-risk patients, regular medical tests are conducted to make sure the cancer isn’t spreading. No other action is taken because the cancer is stable or growing so slowly it won’t cause problems right away. If tests show the cancer is spreading, treatments can begin. Of those men assigned to active surveillance, about one-third will eventually need to have surgery or radiation.

The second approach to treating localized prostate cancer has been the use of radiation or surgery. This is effective for removing any tumors present but is typically associated with side effects in the urinary, sexual, and bowel function. Two common side effects include loss of control over urinary functions (incontinence) and erectile dysfunction

Focal therapy offers a middle-ground treatment. The idea behind focal therapy is to preserve these functions while still treating the cancer effectively.

For men with small, localized prostate tumors, focal therapy as a strategy to treat carefully selected men with prostate cancer. The goal is to successfully destroy areas of cancer and minimize side effects. Focal therapy is a general term for a variety of noninvasive techniques for destroying small tumors inside the prostate while leaving the remaining gland intact and sparing most of its normal tissue.

The idea behind focal therapy is to preserve these functions while still treating the cancer effectively. Focal therapy concentrates on treating “the index lesion,” which is usually defined as a tumor visible on MRI of low or favorable intermediate grade. Even though many cases of prostate cancer have more than one tumor site, some researchers believe that the index lesion is what drives and predicts how any particular cancer will progress. If growth of the index lesion can be controlled with focal therapy, the thought is that the cancer as a whole can be managed safely while minimizing side effects.

 In appropriate situations, focal therapy can offer several advantages for men with early prostate cancer:

  • It can effectively destroy specific areas of cancer within the prostate while preserving normal prostate tissue and function.
  • Side effects, including changes in urinary and sexual function, may occur less often and may be less severe than those associated with more aggressive treatments.
  • We often perform focal therapy on an outpatient basis.

Who are good candidates for focal therapy?

When focal therapy for prostate cancer first began to be used in about 2007, it was only as an alternative to active surveillance in very low-risk patients. Since then, the use of focal therapy has expanded to include those with favorable intermediate risk disease (as defined by the NCCN guidelines). The best candidates have a prostate gland of about 40cc in size or a tumor in the lower half of a larger gland, a single visible tumor on MRI, and the absence of cancer elsewhere in the gland (as proven by biopsies).

In each case, the doctor will consider the patient’s general health and mental outlook, the size and location of the tumors present, and their chances of spreading more. Use of tests such as MRI, ultrasound, and biopsy (tissue samples examined in the laboratory) can help decide if a patient will benefit more from focal therapy or from traditional treatments.


The potential advantages and remaining questions

Because focal therapy treats only the cancerous part of the prostate, and not the whole organ, side effects – including effects to urinary and erectile function – are in theory likely to be less severe than with radical treatments like radiotherapy and surgery.

 The targeted nature of the treatment means that there may also be a shorter recovery time and reduced risk of additional complications like blood loss that can be associated with any radical treatment. But, could this be at the cost of reduced cancer control?

Potential advantages: reduced side effects

So far, results of recent focal therapy trials do look promising in terms of the side effects men experience, but we don’t yet know if they’re really any better than traditional whole-gland options. This is because so far, there haven’t been any trials of focal therapies or radical treatments that are set up to allow comparisons between the two.

Reducing side effects is a major driver for developing new cancer therapies, but it’s not enough on its own. Any new treatment still has to control the cancer effectively. So the big question is, how good is focal therapy at controlling localised prostate cancer?

Remaining questions: cancer control 

The only way to really answer this is to test it out, in clinical trials. Over the last few years, researchers have tested various different types of focal therapies, then monitored the men involved in the trials afterwards to see how they’re doing. Only the two best documented types of focal therapy – cryotherapy and HIFU – have been tested for long enough, and on enough patients, to have published medium term outcomes (this means monitoring patients for three to five years after treatment to see how they do). These results suggest that focal therapy can do a good job of keeping localised prostate cancer under control, at least in the medium term.

But is this good enough? Yet again, that’s a question we can’t answer. At the moment, our best definition of ‘good enough’ is ‘at least as good as radiotherapy or surgery’, and without trials that allow direct comparison between whole-gland and targeted treatment, we just can’t say whether that’s the case. 

Types of focal therapy

There are lots of different kinds of focal therapy, but they all have the same basic principle: using a high dose of energy to kill cancerous cells. Importantly, this energy is highly targeted to avoid side effect-inducing collateral damage.  

But it’s the type of ‘high energy’ that differs between treatments – whether it’s temperature, electricity, or even light. Here, we describe a few different types of focal therapy you might come across.




Cryotherapy was the first kind of focal therapy to come on the scene, after it was developed from a whole-gland version of the treatment. The idea is to rapidly cool the cancerous tissue to around -40oC, triggering a kind of extreme hypothermia in the cancer cells, which kills them. Slowly warming up the area and giving it a second blast of cold makes sure the treatment has been effective. 





High intensity focused ultrasound (HIFU)


HIFU approaches focal therapy from the opposite end of the spectrum – using high temperatures of over 60oC to kill cancer cells. Heat is generated by high energy sound waves, caused ultrasounds. These sound waves are focused by a transducer, in a similar way to how sunlight can be focused with a magnifying glass to burn a hole in a piece of paper. In this way, the sound waves are precisely targeted to burn just the cancerous areas of the prostate, and leave the healthy tissue untouched.






Irreversible electroporation (IRE)

IRE doesn’t use a thermal approach. Instead, pulses of electricity create tiny holes in cancer cells, causing them to die. The electricity can be very finely pinpointed, making this method highly accurate and lending to its commercial name: Nanoknife.

The Nanoknife is already widely used for some types of pancreatic cancer, but in prostate cancer, testing has been slower to take off. So far, this treatment isn’t approved for use outside of research.

Photodynamic therapy


Here, the cancer-killing energy comes from light. Laser beams are used to activate a light-sensitive drug, in precisely the region where it is needed to kill prostate cancer cells. There are a few light-activated drug options out there, but none have yet been proven safe enough for use outside research.










Laser ablation

 The use of laser radiation energy pinpointed to a very small area to burn away cancerous tissue. Some laser ablation has the advantage of being able to be performed at the same time as magnetic resonance imaging (MRI), allowing very specific targeting and also real-time views of results.









Which focal therapy is best?

There are clearly lots of types of focal therapy on the horizon, and the list is likely to keep on growing. But which is best?

For the moment; it’s likely that where the cancer is located in the prostate, and which technique the operator has most expertise in, are likely to be more important factors in determining how successful the treatment is than the type of focal therapy used.

What can be expected after treatment using focal therapy?

Patients treated with focal therapy still need to be actively monitored afterwards. This includes watching for disease that may have gone undetected, has returned, is spreading, or is appearing for the first time. If follow-up tests show that some of the treated cancer still remains, additional ablation, surgery, or radiation may be needed.