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.
Irreverisble 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.
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.
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? We asked Professor Hash Ahmed, clinical oncologist and world-expert in focal therapy, for his advice.
He told us that for the moment, it’s likely that where the cancer is located in the prostate, and which technique the surgeon 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 I say to men is that it’s not really a choice between HIFU, cryotherapy or any other technique. The choice is focal therapy. The types of focal therapies are like different types of knives, and you can leave that decision up to the surgeon.