CyberKnife delivers high dose brachytherapy for prostate cancer
18 April 2008
The CyberKnife robotic radiosurgery system can serve as a
non-invasive means for delivering high dose rate (HDR) brachytherapy
dosing, according to a study published in the International Journal of
Radiation Oncology* Biology* Physics.
The study supports the system's clinical flexibility in treating
prostate cancer and expands the non-invasive options available to
clinicians and patients.
HDR brachytherapy has been shown to be an extremely effective
approach for treating prostate cancer, with substantial clinical
evidence supporting its usage. Nevertheless, the required insertion of
multiple catheters into the prostate, where they remain for the duration
of the procedure (typically 1-3 days), makes it an invasive procedure.
This study demonstrates the CyberKnife System's ability to
non-invasively deliver complex HDR-like radiation dose sculpting to the
prostate, without the need for hospitalisation or anaesthesia,
maximizing patient comfort and convenience. Early clinical outcomes of
the study show a rapid reduction in prostate specific antigen (PSA)
levels with minimal short-term side effects.
"HDR brachytherapy is an effective, accepted treatment for prostate
cancer, but adoption has been limited because it is a difficult
procedure for clinicians to deliver and for patients to undergo," said
Donald Fuller, MD, radiation oncologist, CyberKnife Centers of San Diego
and Radiation Medical Group, and principal investigator in the study.
"Our study concluded that CyberKnife radiosurgery can offer the benefits
of HDR brachytherapy non-invasively on an outpatient basis that is both
easy to deliver and comfortable for patients."
This study, titled 'Virtual HDR(sm) CyberKnife Radiosurgery for
Localized Prostatic Carcinoma: Dosimetry Comparison with HDR
Brachytherapy and Preliminary Clinical Observations' supports the
system's clinical flexibility and demonstrates its capability to create
either a uniform distribution of radiation across the prostate or a
pattern of dose that is similar to HDR brachytherapy.
The System's ability to track the location of the prostate, detect
its position and correct the treatment beam angle continually throughout
treatment ensures that either type of plan can be delivered accurately,
accounting for the motion of the prostate during the treatment. The
CyberKnife System gives clinicians a variety of non-invasive treatment
delivery options, allowing them to customize the treatment to each
patient's specific case.
"We are pleased to have published support of the CyberKnife System's
diverse capabilities in prostate cancer planning and look forward to
further clinical evidence following the publication of long term
follow-up studies," said Eric Lindquist, senior vice president and chief
marketing officer of Accuray, the manufacturer of CyberKnife.
Explanation of HDR Brachytherapy
HDR brachytherapy is a procedure commonly used in the treatment of
prostate cancer. The procedure involves the insertion of catheters into
the prostate gland, and then the delivery of a series of radiation
treatments through these catheters.
A computer-controlled machine forces a seed containing a high energy
radioactive source into the catheters one at a time, and then controls
how long this seed remains in each of the catheters. This method allows
different regions of the prostate to receive different doses of
radiation (ie regions of the prostate expected to have large numbers of
tumour cells receive higher doses of radiation than other parts of the
prostate that may have a smaller amount of tumour cells).