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MR spectroscopy may be superior for
determining prostate cancer prognosis
Detailed analysis of tissue chemistry
could identify most appropriate treatment; more study needed
BOSTON - April 15, 2005 - A
new way of evaluating prostate tumors with may help physicians and
patients choose the best treatment strategy. Using magnetic
resonance (MR) spectroscopy, which provides detailed information
on the chemical composition of tissue samples, researchers from
Massachusetts General Hospital (MGH) have shown that chemical profiles
of prostate tissue can determine a tumor's prognosis better than
standard pathological studies do. The report appears in the April
15 issue of Cancer Research.
"Our study indicates that analyzing prostate tissue's metabolic
profile may give clinicians additional information about the biologic
status of the disease that could allow them, in consultation with
their patients, to make better-informed decisions on the next steps
to take," says Leo L. Cheng, PhD, of the MGH Radiology
and Pathology
Departments, the report's lead author.
Since the prostate-specific antigen (PSA) test became widely used
to screen for prostate cancer, tumor detection rates have increased
dramatically, particularly among those at early stages of the disease.
But increased detection has led to a clinical dilemma, since standard
histologic evaluation, based on a biopsy sample's appearance under
a microscope, often cannot distinguish which tumors are going to
spread and which are not. Many men live for years with slow-growing
prostate tumors before they die of unrelated causes, and treating
such patients could cause more harm than benefit, Cheng notes. So
finding a better way to determine which patients need aggressive
treatment and which can try watchful waiting has been a major challenge.
Another problem is that a biopsy sample from one area of the prostate
may miss malignant cells elsewhere in the gland. Removal of the
entire prostate can give a more definitive diagnosis, but if the
tumor is a slow-growing one, the patient would have undergone unnecessary
surgery. Surgery also is not appropriate when cancer has already
spread beyond the prostate, since that situation requires other
therapeutic approaches such as chemotherapy or drugs that block
testosterone's action.
Although MR spectroscopy has been used for many years to measure
the chemical composition of materials, including biological samples,
it has not been useful for analyzing tumor specimens. In recent
years, Cheng and his colleagues have been developing a spectroscopic
technique called high-resolution magic angle spinning that provides
detailed analysis of a sample's components without destroying its
cellular structure. The current study was designed to evaluate the
technique's potential for providing information useful for clinical
decision-making in prostate cancer.
The researchers used MR spectroscopy to analyze tissue samples from
82 patients in whom prostate cancer had been confirmed by prostatectomy.
Almost 200 separate samples were studied, including many that appeared
benign to standard histological examination. They then compared
the spectroscopy results - detailed profiles of each sample's chemical
components - with the information gathered from pathological analyses
of the removed glands and the patients' clinical outcomes.
Several chemical components of the tissue samples were found to
correlate with the tumors' invasiveness and aggressiveness, supporting
the potential of these metabolic profiles to provide valuable clinical
information. Perhaps most significantly, even samples of apparently
benign tissue had components that could successfully identify more
and less aggressive tumors elsewhere in the prostate.
"Not only are the spectroscopy studies as good as histopathology
in differentiating cancer cells from benign cells, they may be even
better if they can find these metabolic differences in tissues that
look benign," says Cheng. "We need to do a larger scale,
more systematic study of this technique before it can be applied
to clinical practice. And we hope to collaborate with other institutions
to identify different metabolic profiles that could provide additional
information." Cheng is an assistant professor of Radiology
and Pathology at Harvard Medical School.
The study's co-authors are Melissa Burns, Jennifer Taylor, Chin-Lee
Wu, MD, PhD, and Wenlei He, MD, PhD, of MGH Pathology; Elkan Halpern,
PhD, MGH Radiology; and Scott McDougal, MD, chief of MGH Urology.
The study was supported by grants from the National Institutes of
Health and the U.S. Department of Defense.
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 more than $450 million
and major research centers in AIDS, cardiovascular research, cancer,
cutaneous biology, medical imaging, neurodegenerative disorders,
transplantation biology and photomedicine. In 1994, MGH and Brigham
and Women's Hospital joined to form Partners HealthCare System,
an integrated health care delivery system comprising the two academic
medical centers, specialty and community hospitals, a network of
physician groups, and nonacute and home health services.
Media Contact: Sue
McGreevey, MGH Public Affairs
Physician Referral Service: 1-800-388-4644
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