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Cell Loss Said Key
To Cancer Treatment

A loss of cells rather than
increased cell production may be an
influential factor in the better
understanding and possible treatment
of cancer, according to a
University researcher.

William B. Looney, director of
the division of radiobiology and
biophysics of the departments of
pediatrics and radiology at the
University's School of Medicine,
has been measuring experimental
tumor growth by various means and
has found a significant discrepancy
in rates of growth among methods.

In one method, data on growth
rates of tumors was fed into a
computer which charted the growth
of the tumor's volume in length,
width and height per day. The
resulting graph showed a steep
upward curve as the volume of the
tumor increased. "This method of
measuring volume, rather than
strictly linear growth, is not new,"
says Dr. Looney. "However, we
have refined it by asking the
computer to get us the best fit or
method of graphing the growth
rate."

Besides measuring tumor growth
externally by measuring volume,
Dr. Looney and his associates
measured the cell growth internally
through auto radiographic studies. A
radioactive "label" or compound is
injected into laboratory animals
and taken up by the DNA - the
substance that controls heredity -
of the tumor cells. Radioactive
decay of the labeled DNA is
registered on a photographic plate,
and the progress of the cell as it
divides and multiplies can be
followed.

Auto radiographic Method

"From the data found in the
auto radiographic method, we
would expect the specific tumor
used to double in volume in two
days," says Dr. Looney. "But the
external measurements showed the
tumor to double in six days a
rate one-third that calculated by
the internal method.

"One interpretation of this discrepancy
is that cells are being lost
at the same time that they are
multiplying. The important thing,
then, is not cell proliferation but
net cell growth," says Dr. Looney.

The cell loss factor has implications
for treatment, he says. Some
anti-cancer agents have been
thought to kill cancer cells but it
may be that they only stop cells
from growing and the tumor
decreases in size because of cells
being lost or dying. "This opens up
new ways of looking at tumor
growth," says Dr. Looney.

Co-operative Venture

The research, a co-operative
venture among the divisions of
radiology and biophysics and biomedical
engineering, the department
of clinical pathology and the
Computer Science Center, is financed
by grants from the American
Cancer Society and the U.S. Public
Health Service. "We are looking at
how tumors grow - not why they
grow. We hope to gain new insights
into the problems of tumor
growth," Dr. Looney reports.