The CyberKnife belongs to a new class of radiotherapy techniques called IGRT (image-guided radiotherapy). It is a type of radiosurgery, a name for a group of techniques that uses computer simulated delivery of radiation. The CyberKnife is theoretically unique in that it uses a compact linear accelerator (LINAC) mounted on an image-guided robotic arm to deliver multiple beams of high energy x-rays to a target. The ability of the CyberKnife to shape the profile of radiation to conform to the patient’s individual anatomy allows for maximum sparing of surrounding normal tissues. The CyberKnife accomplishes this by accurately cross-firing approximately 150 beams of radiation at the target from multiple directions. There are no studies comparing cyberknife or radiosurgey to other conformal radiation techniques – IMRT, Tomotherapy, or to standard therapies, prostatectomy of standard radiaton therapy.
CyberKnife® radiosurgery represents an extremely attractive therapeutic option as monotherapy for early stage prostate cancer patients, seemingly addressing the shortcomings of virtually all other local therapy options, creating surgical precision but without the hospitalization, and requiring far less investment of time compared with EBRT. This treatment is currently best administered under the direction of an approved clinical trial until further experience is gained, validating the curative potential of this treatment technique, and its sharp therapeutic margin dictates careful patient selection when used as monotherapy. Pending further investigation, CyberKnife® radiosurgery may also evolve to a useful new option for patients with locally recurrent disease following external beam radiotherapy, who have previously had limited further safe and effective treatment available. With regards to prostate cancer, the available literature consists of feasibility studies and phase II studies. NCCN echoes this analysis on MS-9. It says: “Stereotactic Body Radiation Therapy (SBRT) delivers highly conformal, high-dose radiation in 5 or fewer treatment fractions, which are safe to administer only with precise delivery. Single institution series with median follow-up as long as 5 years report that biochemical progression-free survival is 90% – 100% and early toxicity (bladder, rectal, and quality of life) is similar to other standard radiation techniques.”
King CR, Lehmann J, Adler JR, Hai J. CyberKnife radiotherapy for localized prostate cancer: rationale and technical feasibility. Technol Cancer Res Treat. 2003 Feb;2(1):25-30
Chang SD, Main W, Martin DP, Gibbs IC, Heilbrun MP. An analysis of the accuracy of the CyberKnife: a robotic frameless stereotactic radiosurgical system. Neurosurgery. 2003 Jan;52(1):140-6; discussion 146-7.
Madsen, B. L., his, R. A., Pham, H. T., Fowler, J. F., Esagui, L., 12. Corman, J. Stereotactic
hypofractionated accurate radiotherapy of the prostate (SHARP), 33.5 Gy in five fractions for localized
disease: first clinical trial results. Int J Radiat Oncol Biol Phys 67(4),1099-1105 (2007).
King CR, Brooks JD, Gill H, Pawlicki T, Cotrutz C, Presti JC Jr. Stereotactic body radiotherapy for
localized prostate cancer: interim results of a prospective phase II clinical trial. Int J Radiat Oncol Biol
Phys. 2009 Mar 15;73(4):1043-8.
Friedland JL, Freeman DE, Masterson-McGary ME, Spellberg DM. Stereotactic body radiotherapy:an emerging treatment approach for localized prostate cancer. Technol Cancer Res Treat. 2009
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