Common Questions about CyberKnife

The same questions often come up during a consultation.  Hopefully these answers will cover many of your questions and also provide an overview of the treatment process.  Please see my website for more information about every step of the process.

What is the best treatment for me?

Prostate cancer is unique because there are a dozen different ways to treat it.  Everyone wants a treatment which will cure the cancer, but is not overkill and will not result in unnecessary side effects such as urine leakage or erectile dysfunction (E.D.)  As a result, it can be gut wrenching to decide on the best treatment.   Specialists tend to promote the treatment which they themselves perform.  There can also be a difference in results depending on the expertise of the physician.  There is very little research which compares one treatment to another.   Oftentimes all we can say “these two treatments are in the same ballpark” for cure rates.  It is possible that CyberKnife has a higher cure rate than surgery.  Or perhaps surgery has a higher cure rate.  The 10 years results for CyberKnife are fantastic and I would happily put them up against surgery or other forms of radiation.

It often boils down to personal choice.  What makes the most sense to you?  Patients often ask me which treatment I would choose – but the right choice for me may not be the right one for you!

Is CyberKnife the best type of radiation?

CyberKnife uses a special radiation technique called “stereotactic body radiation therapy” (SBRT).  SBRT is different from normal radiation which is called IMRT.   SBRT takes 5 treatments.  Prostate IMRT takes 33 – 45 treatments.  SBRT uses a higher radiation dose each day, is aimed more precisely, and typically a smaller area is treated. Prostate cancer seems to respond very well to the larger daily doses of SBRT, and SBRT may have a higher cure rate than IMRT for prostate cancer.

CyberKnife stands out in the crowd for several reasons: 1) Cyberknife uses a robot arm, and if the prostate gland moves it can track the movement and adjust its beams.  2) It is a dedicated stereotactic treatment machine, unlike other machines which do both IMRT and SBRT.  It does this one thing very well.  3) Radiation beams can enter the body from more angles, which reduces the dose to normal organs, and 4) the radiation beams are smaller and “sharper”.   Over the years I have used many different radiation treatment machines for prostate cancer, but if I had my choice I would pick CyberKnife.

How are the gold markers put into the prostate gland?

I do the procedure personally.  We use a light general anesthetic in a surgical suite, although some doctors do it under local anesthetic.  Once you are asleep, your legs are placed in stirrups and an ultrasound is placed in the rectum.  A needle is inserted through the perineum, which is the patch of skin in between the testicles and anus.  Once the needle has been advanced into the prostate, a marker seed is injected into the prostate gland.  We inject 4 seeds, each one in a different location in the prostate.  The marker seeds do not correspond to where your cancer is.  The entire prostate gland (and tumor) is mapped out relative to the seed locations, in other words the seeds create a sort of GPS coordinate system for the prostate gland.  We use marker seeds because the CyberKnife machine can see the marker seeds, and can lock onto the prostate gland during treatment.

During the same procedure, SpaceOAR hydrogel is injected.  10cc ( 1/3 of an ounce ) of gel is injected in between the prostate gland and the rectum.  This gel turns solid after it is injected, and it pushes the rectum away from the prostate, resulting in less radiation beams hitting the rectum. The body breaks down the gel after 3 months.

Are the gold markers removed?

No, they remain in the prostate gland permanently.  They cannot be removed.  They are pure gold, so they do not react with your body and they do not cause any symptoms.  Each marker seed is very tiny.  The marker seeds are not radioactive.

Is there a knife or any cutting involved in the treatment?

CyberKnife does not use a knife!  It is called that because it is a computer robot-guided treatment that is an alternative to surgery.  It was originally used as an alternative to brain surgery, but is now used as an alternative to surgery for tumors in many parts of the body including brain, lung, liver, spine, and prostate.

The only invasive part of the treatment is when the gold marker seeds and SpaceOAR gel are placed.  This is done a single time under anesthesia and takes 20 minutes.  We use needles to inject the marker seeds and to inject the gel.  There is no cutting.

Is hormone therapy used?

Hormone therapy, also known as androgen deprivation therapy (ADT), involves injections which lower testosterone, the male hormone.  Hormone therapy is often combined with conventional radiation (IMRT) because it can improve the chances of cure.  However, there is no advantage to combining hormonal therapy with the high daily doses of CyberKnife.  Occasionally if the prostate gland is very large, we may need to shrink it first with 3 – 6 months of hormone therapy before doing CyberKnife.

In cases of aggressive prostate cancer (PSA over 15, and/or high Gleason score of 8-10, and/or stage III) we may do “triple therapy”, where we combine 5 weeks of IMRT with Cyberknife boost and  6 – 24 months of hormone therapy.  If hormone therapy is used, we start it 3 months before the radiation starts.

When can I start the treatment and how long does it take?

We first must wait for approval from your medical insurance company before we can start the process.  The entire process can then be done in as little 16 days, and here is an example schedule:

Thu Day 1:  Pre-op visits
Fri  Day 2:  Placement of gold marker seeds and SpaceOAR
Mon Day 5:  Mapping with CT-Simulation and MRI prostate
Thu Day 8:  First Cyberknife
Fri  Day 9:  Second Cyberknife
Mon Day 12:  Third Cyberknife
Wed Day 14:  Fourth CyberKnife
Fri  Day 16:  Fifth CyberKnife.  Can go home immediately after.

Note that Cyberknife treatments are done approximately every second day.  We treat only on weekdays.  Each treatment takes about 1 hour in length.  There is a minimum 3 day gap after gold marker seeds are placed before we do the mapping, to allow the seeds to “settle”.  There is a time gap after we do the mapping to give us time to create the computer treatment plan.

How long can I wait before starting treatment?

I usually recommend starting within 2 – 3 months.  But this is not a hard rule.  Since active surveillance (watching the cancer) is an option for prostate cancer, theoretically you can wait longer if you monitor the PSA every 3 months.  With stage 1 prostate cancer ( ie PSA less than 10 and Gleason score 6 ) it is usually safe to wait.

Am I radioactive or any danger to others?

Not at all.  You are never radioactive.  Your treatment and your cancer pose no danger to others, and there are no restrictions.  You can also continue to have sexual relations during the treatment period.

What is the recovery period like?  When can I return to work?

Unlike surgery, there is no recovery time.  Men who live in the area can continue to work during the treatment period.  If you have traveled for treatment, you can travel home immediately after the final treatment and resume work.

Does the radiation also hit other organs?

Yes it does, but the surrounding organs such as rectum and bladder will receive less radiation.  Cyberknife uses over 100 radiation beams, and these beams pass through the body on the way to the prostate. These beams are all aimed at the prostate gland where they overlap giving a very high dose to the prostate.  The further away from the prostate gland, the fewer beams will overlap and the smaller the radiation dose will be.

Do you just treat the tumor or the entire prostate?

The entire prostate gland is treated.  Whenever possible some extra radiation dose is aimed at the tumor in the prostate.  I frequently lower the dose to the urethra (urine passage) a little.

What are the side effects?

During the 2 weeks of treatment there are minimal side effects.  Once the treatment is finished, short term side effects may develop for the next 4 – 6 weeks with some urine burning / discomfort, a slower stream, and more frequent urination.  We prescribe Flomax to help with these symptoms.  There may also be some irritation of the rectum along with some mucous in the bowel movements.  These short term side effects will usually go completely away.

In the long term, which sometimes takes years to develop, there may be weakening of the erections causing erectile dysfunction (ED).  Viagra or Cialis can help.  There can be some scarring and narrowing of the urine passage (urethra) where it passes through the prostate, resulting in a slower stream.  Rarely / occasionally a dilatation or T.U.R.P. is required.

What happens to the prostate gland after treatment?

The prostate normally produces some of the fluid in the ejaculation.  After radiation, the gland tissue in the prostate will mostly disappear and become replaced with fibrous scar tissue.  The prostate will shrink.  It will no longer produce fluid in the ejaculation, however the sensation may still be the same.

What happens to the dead cancer cells?

Billions of healthy cells die in your body every day, and they are broken down and recycled into your bloodstream. A dead cancer cell is dealt with the same way as any other dead cell in your body. A dead cancer cell is not dangerous.

I heard that you cannot have surgery if the cancer returns after you have had CyberKnife…

True.  But, CyberKnife is very successful at controlling the cancer in the prostate gland so this is not something we usually need to worry about.  According to Dr. Katz’s 10 year results, 98% of the patients have the cancer controlled in the prostate.  In the uncommon case where the cancer does come back in the prostate after CyberKnife then you may be referred for cryotherapy (freezing) or HIFU (heating) of the prostate.

Can radiation be repeated if it does not work?

No.  It is a one time treatment.  We can radiate tumors in other areas of the body but we cannot radiate the prostate gland a second time after CyberKnife.   The reason is because radiation creates some long-term scarring (fibrosis) in the prostate area, and additional radiation would worsen the scarring creating a risk of serious rectal damage or urine leakage.

I heard that radiation is only good for 5 years…

False.  In 2017 10 year results were published by Dr. Katz, and 98% of the stage 1 patients still had cancer control in the prostate gland 10 years after treatment.  93% of the patients had a PSA that was still low and in control.  It is true that prostate cancer can sometimes come back 5 – 10 years or more after either surgery or radiation or any other treatment.  No treatment is a guarantee, but CyberKnife appears to have truly excellent 10 year results.  These results may even be better than those for surgery, but it is difficult to do an exact comparison.  In Dr. Walsh’s results for prostatectomy, 70% of his patients had an undetectable PSA at ten years and there was a 96% cancer control rate in the prostate surgical area.  With CyberKnife it was 93% and 98%.

How do you know the cancer is cured?

There is no test to prove the cancer is cured.  We monitor the PSA blood test every 3 – 6 months, and it will usually drop over several years, often getting as low as 0.1 – 0.2 by five years after treatment.  As long as the PSA drops like it is supposed to then the cancer is considered to be in control, and the longer it is in control the higher the chance it is cured.

What happens if the cancer comes back?

Usually the first sign of a problem is that the PSA begins to rise.  PSA levels can bounce up and down a little day to day, so if it rises the first rule is to not panic and to simply recheck it in 3 months.  If it rises on 3 consecutive occasions and/or if the PSA rises to 2 points above its post-treatment minimum value then there could be a cancer recurrence.

If the PSA trend is concerning then we will do CT scans and a bone scan to look for prostate cancer in the bones or lymph glands.  If the cancer is coming back in the bones or lymph glands then it is usually no longer curable and the treatment will be long term hormone therapy such as Lupron.  If the scans are normal we may do a biopsy of the prostate gland.  If the cancer is found in the prostate gland and not in the bones or lymph glands, then you may be referred for cryotherapy or HIFU.

Do I need to come back for followup visits and PSA blood tests?

We usually do the first followup visit 3 months after the treatment.  The PSA is typically down to 1 – 2 at that visit, but will eventually drop to 0.1 – 0.2 by the five year mark.   After the first visit, PSA’s can be checked every 6 months, provided the PSA is dropping like expected.  If the PSA is not responding well or is rising then we may recommend you get the PSA checked every 3 months.

You can get your PSAs and followups done with your local family doctor or urologist if you wish to.  You can also email me your PSA value anytime.