Stereotactic body radiation therapy (SBRT) delivered by CyberKnife has distinct advantages over other treatments
Having performed more than 1,500 CyberKnife prostate cancer treatments, if I didn’t know better I would think that this technology was created specifically to treat this disease. It is completely suited to the specific challenges of prostate cancer treatment. Yet CyberKnife was first used mostly as a treatment for head, neck and spine tumors that were very difficult to reach.
The Food and Drug Administration (FDA) opened the door in 2001 to the use of CyberKnife to treat other cancers in the body. Since then urologists and oncologists are turning more and more to CyberKnife, as are patients.
CyberKnife’s primary advantages relate to reduced damage to healthy tissue surrounding the cancerous prostate tissues. This is largely due to CyberKnife’s ability to precisely target a tumor in the prostate without radiating healthy tissue. Damaging healthy tissue is the leading cause of side effects from radiation treatment.
SBRT limits the field of radiation
CyberKnife is a form of stereotactic body radiation therapy (SBRT), which is a coordinated system to exactly locate the tumor and limit the field of radiation treatment. SBRT delivers a single high dose of radiation or a few fractionized radiation treatments.
There are various types of SBRT, and I believe CyberKnife is the best. CyberKnife utilizes a robotic arm to deliver radiation in different ways and at different angles.
Ever try to slice a grape? It almost seems to squiggle away from the blade, and can result in a poor cut or even a smashed grape. But if you hold that grape against the cutting board between two fingers so it doesn’t move, you can slice it precisely the way you want.
The tumor under prostate cancer treatment acts much like the grape: It squiggles away. That’s because the prostate moves unpredictably, caused by air passing through the rectum and by the filling and emptying movements of the bladder, not to mention the patient sneezing – or just breathing.
The CyberKnife Robotic Surgery System blends robotics, computer-processing power, advanced imaging and the surgeon’s skill to make instantaneous corrections in radiation delivery. This is possible despite any movement of the patient or the prostate cancer tumor being targeted.
We accomplish this by injecting 3-5 tiny, gold reference-point markers into the prostate to guide the radiation beams. The patient lies comfortably in a custom made body cradle that molds to his body and ensures the same positioning during each treatment. The robotic arm swivels around the patient and delivers radiation at the precisely targeted tumor from various angles.
The big 3 benefits of this prostate cancer treatment
Most often we use CyberKnife by itself in prostate cancer treatment to treat early stage cancer that only affects the prostate and not surrounding areas. We also use CyberKnife in conjunction with other treatments such as traditional radiation when the cancer has spread beyond the prostate.
Prostate cancer patients treated with CyberKnife realize three benefits. These three benefits, in order of importance, follow.
Clinical experiences published about CyberKnife prostate cancer treatment show a 93 percent recurrence-free rate five years after treatment; 94 percent recurrence-free rate at four years after treatment; and up to 100 percent recurrence-free rate after 44 months. Results also show lowered prostate-specific antigen (PSA) levels, which are recoded before treatment and tracked afterward and are good indications of longer-term recurrence-free rates.
Fewer side effects
Less toxicity following prostate cancer treatment or any cancer treatment means fewer side effects. The primary side effects from radiation treatment for prostate cancer are erectile dysfunction due to genitourinary toxicity and damage to the bowels and urinary function from gastrointestinal toxicity. These are graded from 0-4, with 0 being no toxicity and 4 being extreme toxicity.
The clinical studies on CyberKnife show that toxicity from the treatment is low, with grade 2-3 levels at 20-60 months following CyberKnife ranging from 2-10 percent for urinary toxicity and less for bowel toxicity (0-5 percent). Erectile dysfunction ranged from 60 percent to 13 percent, depending on the stage of the cancer and whether the prostate gland was precisely located.
Fewer treatments in less time
Compared with standard radiation treatment, CyberKnife delivers 4 times the usual dose of radiation per day, but with half the overall radiation dose over the full course of treatment. That’s because CyberKnife allows the higher dose to be more accurately delivered to “hug the prostate tumor” and spare the surrounding healthy tissue.
That means each CyberKnife treatment only takes about 45 minutes per day for about five days. Normal radiation treatment takes longer per session and sessions go on from 6-8 weeks. For younger men 50-60, who are likely to be working still, this is a valuable convenience.
I urge all men with prostate cancer to consider CyberKnife for treatment. It’s not for every man with prostate cancer that needs to be treated, but it’s a great option for a lot of them.