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Proton beam therapy may improve treatment
of rare but aggressive tumor
Focusing radiation in the affected
area leads to better control of cranial-base tumort
BOSTON - November 20, 2006 - Proton beam radiation therapy,
a very precise type of radiation treatment, may be an effective
treatment for advanced adenoid cystic carcinoma that has spread
to the cranial base, according to a study from the Francis
H. Burr Proton Therapy Center at Massachusetts General Hospital
(MGH). In the November issue of Archives of Otolaryngology -
Head and Neck Surgery, the research team describes results from
11 years of using proton therapy to treat this tumor, which can
be dangerous when it spreads into the complex structures at the
base of the skull.
"We are very encouraged by our results, in which local tumor
control of advanced adenoid cystic carcinoma of the cranial base
compared very favorably with results reported from traditional radiation
therapy," says Annie Chan, MD, MGH Radiation Oncology, who
led the study.
Frequently originating in the salivary glands, adenoid cystic carcinoma
is an indolent but aggressive tumor that is usually treated surgically
if diagnosed at an early stage. However, when it originates in or
spreads into the cranial base - a complex area involving the cranial
nerves, the eyes and critical brain structures - it is impossible
to remove the tumor safely. Traditional radiation therapy has had
limited success in controlling the tumors' growth, largely because
the sensitive adjacent structures sharply limit the ability to deliver
a strong enough dose.
Proton therapy takes advantage of an inherent quality of the positively
charged atomic particles. As they travel through tissues, protons
release most of their energy in a concentrated burst near the end
of their range, which allows the power of the proton beam to be
focused extremely precisely and spares surrounding structures. The
MGH has used proton therapy to treat a variety of benign and malignant
conditions since 1961 and in 2001 opened the Burr Proton Therapy
Center, at the time the second hospital-based center in the world.
Currently, proton therapy is offered in 25 centers worldwide, five
of which are in the U.S.
The current study reports on a group of patients with very locally
advanced adenoid cystic carcinoma involving the cranial base who
were treated with high-dose proton beam therapy during the years
1991 through 2002. The majority of the patients could not undergo
surgery, as the tumors were very advanced and involved critical
structures in the brain or the cranial base. Patients were treated
with high-dose proton beam radiation therapy, with treatment plans
individually designed to target their specific tumors.
With proton beam treatment, only 9 percent of patients had local
recurrence of their tumors, while with traditional radiation tumors
recur locally more than 70 percent of the time. With tumors controlled
locally in most patients, cancer that did recur was in the form
of distant metastasis. However, more than half the patients remained
free of recurrence through the end of the study period, up to eight
years after surgery. Although blindness is a common side effect
of traditional radiation to this area, none of the patients developed
blindness with the proton beam treatment.
While the results of this study - the first known report of the
use of proton beam therapy to treat this tumor - are better than
trials of other types of radiation treatment, the researchers note
that conducting the kind of randomized trial required to confirm
a treatment's superiority would be difficult for such a rare tumor.
However, multi-institutional prospective studies could further study
the use of proton beam therapy to treat this rare and aggressive
malignancy.
"We are now investigating whether combining proton beam radiation
therapy with chemotherapy could further improve the outcome for
these patients," says Chan, an assistant professor of Radiation
Oncology at Harvard Medical School. The study was supported by the
National Institutes of Health.
The study's first author was Pascal Pommier, MD, formerly of MGH
Radiation Oncology and now at the Anticancer Center in Lyon, France.
Additional co-authors are Jay Loeffler, MD, Nobert Liebsch, MD,
PhD, Fred Barker II, MD, Judy Adams, CMD, and Vrishali Lopes of
the MGH; Daniel Deschler, MD, and Derrick Lin, MD, Massachusetts
Eye and Ear Infirmary; James McIntyre, MD, now at North Shore Medical
Center; and Mark Varvares, MD, now at St. Louis University School
of Medicine.
Massachusetts General Hospital, established in 1811, is the original
and largest teaching hospital of Harvard Medical School. The MGH
conducts the largest hospital-based research program in the United
States, with an annual research budget of nearly $500 million and
major research centers in AIDS, cardiovascular research, cancer,
computational and integrative biology, cutaneous biology, human
genetics, medical imaging, neurodegenerative disorders, regenerative
medicine, transplantation biology and photomedicine. MGH and Brigham
and Women's Hospital are founding members of Partners HealthCare
HealthCare System, a Boston-based integrated health care delivery
system.
Media Contact: Sue
McGreevey, MGH Public Affairs
Physician Referral Service: 1-800-388-4644
Information about Clinical Trials
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