HIFU (High Intensity Focused Ultrasound) is a new treatment option for localized prostate cancer.
Ultrasound wave emission is based on transducer vibration. This results in dilatation and contraction modification of acoustical pressure. The acoustical pressure creates tissue movement (dilatation and contraction) whose amplitude is directly related to the pressure level. As the tissue response is not perfectly elastic, energy is lost and converted into heat.
By using a spherical shaped transducer, the ultrasound beam is concentrated on the transducer focus point, resulting in a maximum of pressure concentrated at this point. As tissue heating is directly related to pressure maximum, the necrotic lesion is formed at the transducer focus.
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Treatments are performed as an outpatient procedure. The night before the treatment the patient is given an enema for colorectal preparation.
The treatment is performed transrectally generally under spinal or epidural anesthesia. A probe is placed in the rectum with the patient lying in the right lateral position. This probe emits a beam of high intensity convergent ultrasound. At the point where the ultrasound waves are focused (focal point) the sudden and intense absorption of the ultrasound beam creates a sudden elevation of the temperature (to greater than 85°C), which destroys the cells located in the targeted zone.
The targeted zone destroyed by each pulse is oval-shaped and measures from 19 to 24mm in height, 1.7mm in width and 1.7mm in thickness. By repeating the pulses, and moving the focal point, it is possible to destroy the volume of the whole tumor (400 to 600 pulses are generally done to treat the volume previously defined).
The treatment duration varies according to prostate volume (1 to 3 hours). Swelling of the prostate appears immediately after the treatment and compresses the urethra. A temporary urinary catheter is placed until the edema recedes (which takes generally from 7-14 days, depending on the case).
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Additionally,
as initial treatment
This treatment is recommended for patients with localized cancer (stages T-1 and T-2) who are not candidates for a prostatectomy (because of their age, their general state of being or an associated disease), or patients who want an alternative to surgery or radiation.
as a salvage treatment
This treatment can be used for cure with patients who have local recurrence after external beam radiation therapy (EBRT) or "salvage" treatment.
repeated treatment
A repeated treatment a few months later is feasible, if the whole tumour has not been destroyed.
This is an new treatment modality which need further observations to describe all the complications.
Mild bleeding in the beginning of micturition, frequent and sometimes urgent micturition, urine leakage on exertion, and elimination of necrotic debris are usually transient and limited..
Urethral Stenosis can occur in the months following the treatment due to scar tissue replacing the treated prostate tissue. In some cases a transurethral urethrotomy may be required.
There have been no GI system complications reported when Ablatherm® HIFU was used in the initial treatment of T-1 or T-2 cancer of the prostate. In the cases where Ablatherm® HIFU was used in patients with previous radiation treatment failures, there were some reports of mild rectal burning.
When the entire gland is treated, potency is retained in approximately 40% of cases. However, with a nerve sparing procedure, potency is retained in approximately 80% of patients. In addition, the majority of patients who are impotent following an Ablatherm® HIFU treatment will respond readily to oral medications (Viagra, Levitra, Cialis) for erectile dysfunction.