New
Radiation System Promises More Precise Treatment for Hard-to-Reach Cancers continued
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Prior to treatment, a
patient undergoes computed tomography imaging to precisely define both the tumor and
adjacent normal tissues. This information then is put into a treatment planning computer.
The computer subsequently marks as many radiation targets in the tumor location as
necessary.
During treatment, Dr. Werner-Wasik
explains, the device's controller opens and closes, changing the radiation beam intensity
and shape as the treatment table and the linearaccelerator head move, depending on the
radiation needs in treating the tumor. Once the first area is treated, a crane moves the
table and the patient, and a new area is treated. Depending on the size and location of
the tumor, the patient may be treated once or during several sessions.
Testing, Clinical Trials Needed
According to Dr. Werner-Wasik,
before the system is operational, it requires testing with Jefferson's linear accelerator,
with which it fits. Engineers attach a device called a multileaf intensity modulating
collimator, or MiMic, to the head of the linear accelerator. The first patient is expected
to be treated with the system in fall 1998.
Jefferson is the first medical center in the Delaware Valley
and one of approximately 26 centers nationwide to have such technology. One goal, once the
FDA-approved Peacock system is completely functional, is to eventually participate in
multicenter clinical trials testing how well the device actually works in treating cancer.
There are no long-term data on the effectiveness of Peacock versus conventional radiation
therapy in treating patients, she says. "Clinical trials will help us establish
efficacy and toxicity levels,'' she says. In any case, treatment with Peacock will spare
more normal tissue than would conventional therapy.
But Peacock is not for every hospital, and it certainly is not
for every patient. Only those patients with particular types of tumors may be eligible to
be treated with the device. In addition, the system as yet is not easy to use. "It's
a major endeavor requiring sufficient medical physics expertise," Dr. Werner-Wasik
explains. "At least initially, its use will likely be reserved for tertiary-care
centers with sufficient medical physics resources."
Some tumors are not satisfactorily controlled by radiation,
she notes, such as lung and prostate cancers. The prostate is located deeply in the pelvis
and surrounded by normal structures, including the bladder and rectum. "If we can
increase the radiation dose to prostate or lung cancer tumors, and not to the nearby
normal tissue, hopefully we increase the likelihood of a cure."Second Treatments Possible
Dr. Werner-Wasik notes that the first tumors for which this technology will be used at
Jefferson are located in the head and neck region and in the brain. She also believes that
the device will enable radiation oncologists to provide more second courses of
radiotherapy. "It is dangerous in certain situations to give second courses of
treatments to some patients. The Peacock may allow us in some cases to treat tumors
that recur after initial courses of radiation." |
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Radiation
Oncology Clinical
Trials Look at Both Treatment
And Prevention
Researchers in the Department of Radiation Oncology conduct numerous
clinical trials. One, known by the acronym LAMP, is a 40-center, randomized clinical trial
looking at stage III non-small-cell lung cancer. Patients, the majority of whom have
smoked for a length of time at some point in their lives, receive both chemotherapy and
radiation. The trial is aimed at finding out whether the order in which patients receive
their specific treatments affects their outcome. Dr. Curran, who is the national principal
investigator of the LAMP trial, explains that the trial looks to improve the patient's
median survival time and quality of life. Paclitaxel, one of the chemotherapy drugs being
used, is a promising drug that has "altered the pattern of care for some cancer
patients," he says, particularly for those with ovarian or breast cancers. "We
think we have the ability to improve the lives of many patients by combining such
promising agents with state-of-the-art radiotherapy,"
he says.
Scientists in the department also conduct trials aimed at preventing cancer development.
One trial managed by the Radiation Therapy Oncology Group (RTOG), a National Cancer
Institute-funded consortium, is a nationwide, multicenter trial attempting to reduce
cancer incidence in high-risk populations. The study focuses on those who have early-stage
mouth and throat cancers. Though such disease may be controlled initially by surgery and
radiation,these individuals are at increased risk of developing second cancers.
Jefferson researchers are conducting a randomized, placebo-controlled study comparing a
placebo to cis-retinoic acid. Nationwide, some 900 individuals have participated to date.
Cis-retinoic acid has been shown in the laboratory to reduce the cancerous development of
pre-malignant lesions. |
| For such technology to be
widely used, it
needs to be user friendly and inexpensive. "Eventually, I would hope that this system
and
others under development are utilized appropriately and widely by other medical
centers," she notes. "The theoretical aspects are very appealing to the
radiation oncologist."
Nomos Corporation of Sewickley, Pa.,
developed the Peacock technology.
For more information,
please call
1-800-JEFF-NOW. |
JEFF MED, Thomas lefferson University Hospital's
physician-to-physician referral service offers physicians access to physicians at Thomas
Jefferson University Hospital, 24 hours a day, 7 days a week. One call to 1-888-JEFF-MED
will arrange a physician referral or consult, provide information about current clinical
trials, and facilitate a patient transfer to Thomas Jefferson University Hospital.
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