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University
of Minnesota researchers report that a simple test can be
used to help identify patients with the most aggressive prostate
cancers, even among patients whose tumors have the same Gleason
grade.
Prostate
cancer tumors are graded as to how far they have progressed
based on the shape and microscopic appearance of the tumor,
but the grade does not tell how aggressively they have been
growing or spreading.
Under
the Gleason grading system, patients with a higher score are
at higher risk, but some patients with high scores outlive
others with lower scores.
Now, researchers
report in the journal cancer they believe the ratio of an
enzyme called cathepsin B (CB) to natural inhibitors of CB
called stefins can help identify those patients whose cancers
are more aggressive and likely to spread.
Cancer
cells produce high levels ot the CB enzyme in order to invade
surrounding tissue, but they also produce the stefins that
inhibit CB.
Working
with prostate surgery tissue samples from patients with Gleason
grade 6 tumors, which appeared relatively homogeneous under
the microscope, the researchers found that the ratio of CB
to stefin A was significantly higher in patients whose cancer
had spread to one or more pelvic lymph nodes.
"The
ratio of CB to stefin A reveals differences in tumors that
are not visible under the microscope," said cancer researcher
Akhouri Sinha, a professor of genetics, cell biology, and
development, faculty member of the University of Minnesota
Cancer Center.
"If
this test were done on tumors of newly diagnosed patients,
we would have an indication of which cancers were most aggressive,
and we could give those patients aggressive treatment,"
said Sinha. "Those patients whose tumors show ratios
of one, or less than one, may require less aggressive treatment."
Source:
Prostate Cancer
Week of June 16, 2002
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