CyberKnife Tested for Treatment of
Breast Cancer in Clinical Trial at UT Southwestern
CyberKnife focuses
multiple beams of radiation with millimeter precision, while leaving
surrounding healthy tissue unharmed; painless treatment
Dr. Dan Garwood and radiation
therapist Stella Stevenson (right) show breast-cancer patient
Dr. Kristin Wiginton collimators that fit into the Accuray
CyberKnife System that adjust the amount of radiation the
machine emits during a treatment.
Feb. 15, 2011
Breast-cancer patient Kristin Wiginton is the first to be treated at UT
Southwestern Medical Center, Dallas, with high-beam radiation using the
Accuray CyberKnife System, which doctors say offers improved cosmetic
results, less radiation exposure to surrounding tissue and a shorter
treatment period.
Dr. Wiginton is
among 45 participants in a UT Southwestern-based clinical trial the
first of its kind in the Southwest investigating use of the radiation
delivery system for breast cancer. Her post-lumpectomy therapy lasted
one-third the duration of a typical radiation session for a
breast-cancer patient.
While CyberKnife
has been used at UT Southwestern since 1997, it primarily has been
targeted for tumors of the brain and spine.
"If this had not
worked out for me, I would have gone with six and a half weeks of
traditional radiation," said Dr. Wiginton, 45, an associate professor of
health studies at Texas Woman's University.
Instead, her
treatment took less than two weeks and consisted of five 90-minute
sessions every two to three days. Her final treatment was Feb. 3 at UT
Southwestern University Hospital - Zale Lipshy.
Radiation
therapy following a lumpectomy is commonly recommended to remove
potential residual cancer, said Dr. Robert Timmerman, professor of
radiation oncology and neurological surgery who is leading the study.
Current radiation protocols for breast cancer, however, can be long and
uncomfortable.
Shorter courses
treating smaller breast volumes, called partial breast irradiation, have
shown considerable promise in clinical studies, he said. The most common
partial breast irradiation approach, brachytherapy, requires a catheter
implant via a surgical procedure. Another method delivers the treatment
using conventional radiotherapy equipment but may lead to less-pleasing
cosmetic results.
Dr. Wiginton
described her first CyberKnife session as painless. Though a bit tired,
she said the treatment was not uncomfortable and she spent most of the
time listing to music on her iPod.
"You don't have
to worry about moving too much, because you are put into a mold," she
said, referring to a special padded bed she rested on during the
procedure.
The trial's
protocol is being carried out in conjunction with experts in the UT
Southwestern Center for Breast Care at the Harold C. Simmons Cancer
Center, the only National Cancer Institute-designated center in North
Texas.
Patients
preparing for CyberKnife radiation treatments have minute gold seed
markers called fiducials implanted around the affected breast tissue.
The CyberKnife's image-guided system tracks the fiducials to deliver
radiation to the area, including moving with each breath taken by the
patient.
Instead of
standard radiation therapy systems that require heavy equipment with
very limited maneuverability and beam direction, CyberKnife uses a
lighter linear accelerator on a robotic arm to focus multiple beams of
radiation with a millimeter precision, while leaving surrounding healthy
tissue unharmed.
"The impetus for
this protocol is to avoid that invasiveness while still achieving
excellent cosmetic results," said Dr. Timmerman, referring to the
typical brachytherapy procedure. "This gives the same amount of
radiation, but in a noninvasive way. Each [CyberKnife-delivered] beam is
very weak, so it causes very little entry damage. It will move around to
200 different positions."
Qualified
participants must have localized early-stage breast cancer, must have
successfully underwent a lumpectomy and be at least 18 years old.
Patients will be evaluated over the next 10 years to check if they
remain cancer-free, for potential cosmetic changes in the breast and any
unanticipated effects that may develop from radiation treatment.
Dr. Wiginton,
referred for the study by Dr. Dan Garwood, associate professor of
radiation oncology, said she hopes the procedure will be successful and
offer new radiation therapy options for breast-cancer patients.
Because heart
disease ran her family, traditional radiation therapy wasn't a good
choice for Dr. Wiginton due to potential damage to surrounding tissues,
including the heart. CyberKnife's precision greatly lessened that risk.
"If they're
willing to use it on brain cancer, I think it's a fairly safe bet to use
in a breast," Dr. Wiginton said.
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