HIFU, or High Intensity Focused Ultrasound, is a form of treatment for prostate cancer undergoing clinical trials right now in the United States. This treatment is not new- it has existed for years in Europe and Japan. Results have been mediocre to date, but this technology-driven treatment looks like it is finally ready for the big time.
What is HIFU?
HIFU technology developed in the 1950s originally and was used to treat central nervous system tumors. In the 1990s, experimental work was performed in dog prostate models followed by work with humans. HIFU is a noninvasive (well if you consider a rectal probe noninvasive... there are no incisions and that's why we call it noninvasive) treatment for prostate cancer still contained in the prostate. Ultrasound energy is focused on tissue, bringing its temperature to nearly 100 degrees Celsius in just 2 or 3 seconds. The tissue is literally denatured and dies off.
How does the technology work? The best analogy is to imagine a magnifying glass focusing light on a dry leaf. You could burn a hole in the leaf and literally leave the rest of the leaf untouched. HIFU works the same way. As long as you can image the tissue, you can treat it.
Is this better than radiation? Radiation treatments have made huge strides, especially with IMRT and proton beam treatments. However, these treatments are still radiation. If some surrounding tissue gets treated, who knows what kind of cellular changes could occur over the years to that radiated tissue. Documented cases of secondary cancers, which are worse than the original cancer have been seen years after the orignial treatment. (see: Irradiation sarcoma after external beam radiation therapy for localized adenocarcinoma of the prostate: report of three cases. If HIFU shows good results in its clinical trials, I think it will be a form of treatment that is less toxic than radiation. Ultrasound energy is not ionizing energy like radiation. After all, we use diagnostic ultrasound all the time for imaging body parts and even a pregnant woman's fetus!
What are the results so far?
Again, the technology is undergoing FDA trials right now. Our group, UrologySanAntonio.com is one of the first sites accepted to trial the Sonablate 500, a device manufactured by Focus Surgery in Indiana. The trial will be funded mainly by USHIFU, which is the exclusive distributor of the machine in the Americas. As a disclaimer: I don't have a financial interest in the company. During the trial, patients will be selected based on their prostate cancer's stage. (more later)
There is another HIFU device known as Ablatherm also hopefully starting trials soon. We are comfortable with the Focus Surgery device. Apparently, it is less limited by prostate size and the rectal probe is not as big. Undoubtedly, both companies will continue to innovate and I will try to keep you posted as changes occur.
A paper in Clinical Genitourinary Cancer published in December 2005 summarized available clinical trials to date. Unfortunately, the trials so far are difficult to compare with each other. Some are done with patients with localized cancer, others have patients with more advanced cancer or patients on hormonal therapy, which can confound PSA results. The data so far shows 5-year progression-free survival rates ranging from 68% to 88%. Most of the studies are from Europe and Japan. One American study is reported. This is a pilot study with the Sonoblate 500 device. The data looked at 20 patients with early, localized cancer. These patients actually had to undergo a repeat biopsy at 1 year to check for cancer. Negative biopsies were shown in nearly 2/3 of patients. Some patients needed more than one HIFU treatment.
What are the benefits?
HIFU is nearly painless. Patients typically have an epidural or spinal anesthetic and are home later the same day. The procedure is bloodless, so patients do not feel too weak afterwards. HIFU offers the potential to preserve men's sexual potency. From my observation, the imaging allows you to see the capsule of the prostate. The view becomes a little difficult at the apex and the base of the prostate, but as long as you can make out the capsule, you can precisely treat the prostate and avoid the tissue outside the capsule, which comprises the neurovascular bundle. The bundle is what helps with erections.
Risks?
HIFU is experimental therapy undergoing FDA trials. We need longer term data before we can say this is a substitute for radiation or surgery. There is a risk for urethral strictures, impotence, and incontinence after the procedure. There is also a learning curve. After participating in some treatments, I can say that an understanding of prostate anatomy and ultrasound is very important. An inexperienced surgeon may have real difficulty performing the procedure well. Fortunately, doing hundreds of laparoscopic, robotic-assisted prostatectomy surgeries as well as ultrasound procedures really helps to perform HIFU with a good understanding of the anatomy.
Interested in treatment?
The FDA trial is open to men with prostate size less than 40 cc, a Gleason score of 6 or less, PSA less than 10 who have not had any type of medication or surgery for their prostate cancer. Others who seek treatment and are not candidates for surgery or radiation may have to travel outside the United States for treatment. I have been to Mexico and the Dominican Republic to see these treatments and was astounded at how good the patients look after treatment. Close follow-up with the completion of the FDA trials will help confirm HIFU's role in the urologist's armamentarium against prostate cancer. Feel free to visit my website at www.urologysanantonio.com and email me for more information.
