Mapping Cancer
Chemotherapy has long been considered the gold standard for cancer treatment. although effective, it’s akin to carpet bomb- ing because it destroys both healthy and malignant cells. as a result, patients can
suffer life-threatening complications that are some-
times as dangerous as the disease itself.
Fortunately, doctors now have access to a handful of
potent cancer drugs that can attack the cancer with smart-
bomb accuracy. But figuring out which drug works best
for which cancer has been a slow and painstaking process.
the good news: a national Institutes of health initiative
called the Cancer genome atlas (tCga) promises to expe-
dite progress by building blueprints for 20 different types
of cancer and cataloging the genetic glitches that turn
healthy cells into malignant ones.
tCga has identified more than 200 different types of can-
cer and many more subtypes, each caused by a specific Dna
mutation that triggers the growth of rogue cells. Identifying
the changes in each cancer’s complete set of Dna — its
genome — and understanding how such changes interact to
drive the disease process will lay the foundation for utilizing
drugs that target cancer cells and leave healthy ones alone.
non-small cell lung cancer, for example, is a highly
aggressive tumor that usually isn’t discovered until it has
spread to other organs. patients rarely survive longer than
a year after diagnosis. But while looking at the cell’s molec-
ular structure, researchers discovered that up to 7 percent
of these cancers share a genetic abnormality known as
the alK gene. the alK gene causes about 40,000 cases
of lung cancer worldwide each year. as such, drug compa-
nies were highly motivated to come up with a treatment
that would stop the alK gene cells from replicating.
and in time, they did. In late 2011, the Food and Drug
administration approved the sale of a drug called Xalkori,
which can shrink or stabilize tumors by preventing the
mutated gene from replicating. and it can do so with far
fewer side effects than traditional chemotherapy has.
the discovery of the alK gene was somewhat serendipi-
tous because researchers were not looking at the complete
cancer genome, but instead at a single gene sequence. “It
was a one-off study that hit on something big,” says Dr.
Christopher Benz, co-principal investigator at novato’s
Buck Institute for research on aging and co-principal
investigator at the Buck Institute–UC santa Cruz genome
Data analysis Center, one of seven such centers support-
ing the tCga program nationwide. “moving for ward, the
likelihood of making these discoveries is now exponentially
greater, given the vast scope of the tCga’s current eight-
year in-depth effort analyzing the Dna, rna and protein
expressed by all cancer genes, rather than just single ones,”
says Benz. What’s more, these tCga tumor blueprints are
becoming immediately available for researchers around the
world to download and further analyze so that they can be
used as a springboard for testing even newer hypotheses.
Fortunately,
doctors now
have access to
a handful of
potent cancer
drugs that can
attack the
cancer with
smart-bomb
accuracy.
