CyberKnife® FAQs

Q:  How is CyberKnife® used to treat prostate cancer?

A:  CyberKnife® is targeted, high-dose radiation administered to the cancerous prostate tumour over a series of 1-5 sessions and days. Patients are awake during each 30-90 minute treatment. The radiation used in CyberKnife® treatments is referred to as Stereoactic Body Radiation Therapy (SBRT) and is recommended for men diagnosed with low to moderate risk prostate cancer.

CyberKnife® Robotic Radiosurgery System proves more efficient than ordinary radiation therapy due to a more accurate targeting of the prostate and corrections regarding its movement. Common radiation therapy cannot trace the movement of the prostate during treatment, causing healthy surrounding areas to be affected by the radiation.


Q:  What are the specific steps of the CyberKnife® treatment?

  1. The doctors will require a PSA level test that will provide a basis for interpreting the results of the treatment.
  2. Next up, the doctor will insert fiducial markers into the prostate, through an ultrasound guided needle. This will help the CyberKnife® System with locating the exact position of the prostate along the treatment.
  3. The patient will undergo a CT scan that will detect the exact size, location and shape of the prostate and, if necessary, a MRI scan to fully visualize the prostate and its environment. During the scanning and the treatment, the patient will lay on a custom moulded cradle that will enable him to maintain the same position during the entire time.
  4. Upon consulting the CT scan and MRI results, the medical physicist and the patient’s doctors will devise a treatment plan with optimal radiation delivery.
  5. The treatment will entail that the patient stays still on their custom body cradle. The CyberKnife system’s Computer-controlled robot will trace the position of the prostate and move around the patient’s body to administer precise radiation.
  6. After the session is complete, the patient can go about their day in a normal way and return for additional treatment as indicated by their doctor.
  7. Upon completion of the treatment, the patient will be scheduled for follow-up appointments and have PSA level tests and digital rectal exams as indicated by the doctor.

Q:  What are the advantages of CyberKnife® treatment?

  • The side effects of CyberKnife® treatment are minimal and can include:  burning sensation during urination, low urinary stream, more frequent urination and stools, stools incontinence and more gas during bowel movements.
  • Lower duration of treatment: four to five days as opposed to over 35 days as is the case with regular radiation therapy.
  • Accidental radiation of healthy surrounding areas is massively reduced: the CyberKnife has sub-milimeter clinical accuracy.
  • Minimum to zero recovery time required.
  • Often the most appropriate treatment for inoperable or untreatable tumors.

Q:  What are the disadvantages of CyberKnife®?

A:  Radiosurgery and radiation are “best guess” treatments that attempt to address all cancerous prostate cells. During CyberKnife® therapy, radiation is directed at the cancerous prostate based on pre-treatment biopsy and CT scan data. Imaging information gathered before and during the procedure is used to approximate the radiation dosage based on the location, size, and shape of the tumor.

However, pre-surgery prostate cancer data is not always accurate. Due to limitations in prostate cancer staging diagnostics, the true nature and scope of a man’s tumor is not known until it is visualized during surgery. In these post-surgery tests we learn the exact type of prostate cancer, how extensive it is, as well as the status of the seminal vesicles and lymph nodes. Research shows that prostate cancer tumor staging actually changes in as many as 40% of men after post-surgery lab testing.

Men who choose CyberKnife® radiation will be left with a fluctuating PSA level and non-specific tumor results. After CyberKnife® therapy the tumor can take months or years to disappear, or it may remain in the body permanently with stalled growth. A rigorous follow-up schedule must be maintained to monitor PSA level and tumor status for life. While the hope is that the cancer will not return, the testing and worry can be very draining.

According to CyberKnife® research, 84% of patients chose the treatment method because of their comfort with the expected risks and side effects, but only 59% of men believed the procedure was the most likely to eliminate their prostate cancer.


Q:  How does CyberKnife® Robotic Radiosurgery differ from Robotic Prostatectomy Surgery and Radiation?

A:  CyberKnife® Robotic Radiosurgery is not robot-assisted surgery; it is simply another form of prostate cancer radiation such as external beam radiation therapy (EBRT) or brachytherapy. CyberKnife® is FDA-approved radiation therapy for the treatment of cancer, though the procedure is very new.

During robotic prostatectomy surgery, Dr. Samadi uses real-time, first-hand visualization to assess the prostate cancer scope and remove the tumor. This proven, minimally invasive procedure integrates the precision and visualization of robot-assisted surgery with the expertise of Dr. Samadi’s vast surgical background. With appropriate follow-up and post-surgery care, PSA level should drop to an undetectable level after robotic prostatectomy surgery.

Radiation such as CyberKnife® can be an effective secondary measure for men with high-risk, recurring prostate cancer.


Q:  What are the side effects of Cyber Knife®?

A:  The negative side effects of CyberKnife® can be expected to mirror those of other targeted radiation therapies.

Over the short term, radiation therapy for prostate cancer can cause:

  • Urination problems including burning and blood in the urine
  • Urinary urgency and frequency
  • Weakened urinary stream
  • Incomplete emptying of the bladder
  • Anal and rectal irritation, rectal bleeding, hemorrhoids, and stool problems
  • Fatigue and nausea

Long-term CyberKnife® and prostate cancer radiation side effects may include:

  • Sexual impotence and/or erectile dysfunction for up to 2 years after treatment
  • Delayed orgasm or ejaculation
  • Temporary or permanent reduction in sperm count; fertility should be discussed with your physician prior to CyberKnife® treatment
  • Impaired bowel function
  • Potential increased risk of bladder or rectal cancer by 5%

Follow Dr. David Samadi’s appearance on Fox News for a detailed explanation of the differences between CyberKnife®, Robotic Prostatectomy and Radiaton.


Q:  Will I need additional prostate cancer treatments after CyberKnife®?

A:  Most patients with lower-risk prostate cancer have very positive results after radiation. Your ongoing PSA testing and tumor monitoring will watch for any changes or developments in your prostate cancer. If needed, CyberKnife® therapy can be repeated. Robotic prostatectomy surgery provides greater peace of mind, as the tumor is removed and the PSA should reach an undetectable level.

Q:  What other concerns does CyberKnife® prostate cancer therapy introduce?

A:  If your prostate cancer returns after radiation therapy, it is extremely challenging to perform a successful prostatectomy procedure due to physical alterations caused by the targeted radiation. While Dr. Samadi is highly skilled in performing such operations, relying on CyberKnife® Radiosurgery as an initial prostate cancer treatment may severely limit secondary treatment options if the cancer returns. Radiation for prostate cancer is best reserved as a secondary option should the cancer return.