Focal Ablation
Ablation refers to the destruction of all or part of the prostate gland, in situ, in order to destroy the prostate cancer. Focal ablation usually refers to a highly focussed destruction of just the prostate cancer, leaving other parts of the prostate gland untouched.
Focal ablation techniques are most frequently employed as Salvage procedures, to treat small cancer recurrences particularly after prior Radiotherapy. But there is growing interest and research into using some of these techniques to treat small primary cancers within the prostate gland, instead of radical treatments like surgery and radiotherapy.
In my own case, I’ve reason to believe that my cancer has been cured (but more time is required to prove this). However, it can recur and, as I was treated with Radiotherapy I am unable to use this again as the healthy tissue damage can become too great. I’ve already discussed this with my advisers and I would almost certainly be looking at Focal Ablation should I have a recurrence.
Patients who had Surgery in the first instance can look at Radiotherapy in a recurrence situation and are less likely to be looking at Focal Ablation.
In the video, Dr Mark Scholz of the Prostate Cancer Research Institute (PCRI) discusses various aspects of Focal Ablation. Note that where he says, in the video, that for some patients a “cure” is not being sought, this does not mean that the patient can’t be treated. Once the disease is relatively advanced it can become a “chronic” disease and require repeated treatment. In this situation, the word “remission” is used rather than “cure”.
Cryotherapy
This refers to the destruction of the cancer by using extreme cold, which kills the cells. The extreme cold is generally delivered by Argon gas which has been dropped to a temperature of about -190 degrees Centigrade by a physical process and then delivered through a needle into the prostate gland.
Focal Cryoablation of small cancers can only be done safely using direct In-Bore MRI guidance and control, for real-time visualization of needle placement and liquid Argon delivery, thus ensuring only the cancer and immediate surrounding tissues are destroyed. Most of the prostate gland will be spared.
Cryotherapy is also performed using ultrasound assistance, but this is not a targeted focal ablation, and results in much more of the prostate being destroyed, sometimes the entire gland. Also, because of the amount of tissue destruction, potential complications are greater than with an MRI-guided focal ablation.
After Cryoablation it is usual to be kept in hospital overnight.
The following video is the story of one patient’s choice of Cryotherapy – in 2001. He is still alive and in good health in 2021, 20 years later. Although this video is a bit longer than most, it contains much useful information regarding the importance of diet and exercise.
HIFU
HIFU stands for High Intensity Focussed Ultrasound. It is most commonly performed with ultrasound guidance which allows the focussed ultrasound to be delivered accurately to the area containing the tumour.
It works by heating up the area being targeted to a sufficiently high temperature that the cancer cells die.
It can be used for small lesions as a primary treatment modality, but it is one of the effective treatments available for a post-radiotherapy recurrence that consists of a small lesion within the Prostate Gland.
It is usual to go home on the same day of the treatment.
It’s a treatment modality to consider when looking at the Focal Ablations that are on offer at your Cancer Centre.
Focal Laser Ablation
Using MRI-guidance a Laser probe is positioned at a lesion within the Prostate Gland.
The principle of focal laser ablation therapy is to destroy a tissue target using laser radiation energy. The resulting rapid temperature elevation of the targeted tissue results in in vivo tissue destruction. Prostate tissue is well suited for focal laser ablation due to its optical absorption rate without excess vascularity, which allows for finely controlled ablation.
Effective focal laser ablation for the treatment of prostate cancer requires 1) accurate delivery of the laser energy to the target tissue, 2) sufficient thermal destruction to reliably destroy the target tissue, and 3) minimal thermal destruction to surrounding tissues. Each step provides its own set of technical challenges, but ongoing advances in image acquisition and analysis, bioheat transfer modelling, and laser delivery technology make laser ablation of prostate cancer very feasible.
As with HIFU you should be able to go home on the same day as the procedure is performed.
Electroporation – “NanoKnife”
The technical name for this process is Irreversible Electroporation or (IRE). It is a particularly interesting procedure that kills all types of cancer cells and so is widely applicable. It does not rely on heat, or cold, to eradicate the cancer. The cancerous cells are killed by an electric field.
The most basic setup for the NanoKnife is two electrodes which are positioned in the prostate gland using ultrasound guidance. A voltage, typically 3,000 volts, is applied between these electrodes for a fraction of a second and the cells within the resulting field are eradicated. In practice, to keep the body at zero volts one electrode will be set to +1,500 volts and the other to -1,500 volts. A larger lesion can be handled by inserting more than two electrodes in the prostate gland and then arranging to energise them in pairs.
Once the treatment is complete the electrodes are withdrawn leaving very limited damage to the area. And unlike other treatments this can be performed many times as appropriate to need.
The particular setup and process is simulated in software before the actual treatment is performed. A typical treatment can take as little as 20 minutes, including setup. The patient can go home on the same day and will return a few days later so that the result of the treatment can be established with an MRI scan.
Following this, MRI scans are taken at regular intervals – typically every few months. It is found that the scarred area in the prostate gland shrinks with time.
This treatment modality, as well as being ideal for a small recurrence in the prostate gland, can be used very effectively as a primary treatment in carefully selected patients thereby removing the requirement for radical treatments such as surgery and radiotherapy.
This is definitely a treatment procedure to “keep an eye on”.
Brachytherapy
Brachytherapy can be used as a Focal Ablation technique.
Alex Scholz talks to Dr Jeffrey Demanes