What is HIFU?
High Intensity Focused Ultrasound (HIFU), was first used as a treatment for BPH (benign prostatic hypertrophy) and is now being used as a treatment for prostate cancer. HIFU is not yet approved in the US, but has been used extensively in other nations for several years. It is currently in testing at several cancer centers across the US.
The HIFU Procedure
In this procedure, a special ultrasound probe is placed in the rectum while the patient is anesthesized with an epidural. The physician then views the prostate tissue on a monitor, and maps out the areas of concern. Once the problem areas have been identified, the physician uses a high intensity ultrasound beam that is focused on the exact areas which need treatment. The focused beam creates an intense heat of 176-212 degrees fahrenheit that kills prostate cancer cells. Exposure time of the tissue is short, usually less than one second; and the physician can immediately view the changes in the tissue to verify success.
A primary advantage of using HIFU as opposed to external beam radiation (EBRT) is that only the focus point is heated, the area in the "beam" of the HIFU is unaffected. Only the pinpointed target is exposed to the lethal heat.
HIFU is usually performed as an outpatient procedure, and depending on the equipment used, the patient either lies on his back with legs elevated, or on his side. The specialized probe is inserted into the rectum, and live views are obtained of the prostate on the computer monitor in order to map out the treatment zones. The treatment zones are mapped into the computer and the HIFU treatment begins, one zone at a time. From start to finish, the entire procedure generally takes between 2-4 hours, depending on the number of zones identified and prostate size.
Post Procedure Recovery
The prostate is going to swell because of the heat damage that has occurred, so a foley catheter will be placed through the urethra up into the bladder. The catheter will stay for a minimum of two weeks until urine flow through the urethra can again occur naturally. There will be some lower abdominal and bladder discomfort for the next few days, but you can start resuming your full activities the day after the procedure.
When the foley catheter is removed, it may still take several months for urine stream to return, because the urethra has to heal and the prostate can take several months to start shrinking. You may experience some tissue passage in the urine, this is normal.
Side Effects and Complications
Urinary obstruction and sloughing of prostate tissue out through the urine stream are the two most common complications of HIFU. Infection is always a concern, and long term followup is a necessity after any cancer treatment procedure.
When to Choose HIFU
HIFU is meant primarily as a cure for prostate cancer. Men with cancer that is still confined to the prostate should be considered primary candidates for HIFU. Like cryosurgery, HIFU can treat the prostate as well as surrounding tissue, so it can also be used to treat prostate cancer that has begun to spread to adjacent areas including the capsule or neurovascular bundle. It is important to note that if there has been no spread to the neurovascular bundles, the nerves are spared and erectile function can be maintained.
In summary, the best candidates for HIFU as a primary treatment are those men with prostate cancer in stages T1c-T3. It must be stated that the higher the staging, the higher the risk for prostate cancer metastasis.
Also, if the prostate is very large (over 40 cc), it may be necessary to use hormonal techniques to reduce the size of the prostate before performing HIFU.
HIFU as a Salvage Therapy
HIFU can also be used after radiation therapy, radical prostatectomy, or cryosurgery that has not been completely able to eradicate the cancer. Because of the ability to visualize tumors live then aim the treatment very precisely, it promises to be an option of choice in the future as a salvage therapy.
Summary
High intensity focused ultrasound as a treatment for prostate cancer shows much promise, although it is still awaiting approval in the US. It offers a clear alternative to cryosurgery, radiation seeds, and radical prostatectomy for some patients.
