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WASHINGTON (AP) -- Cancer patients
often wonder "why me?" Does their tumor
run in the family? Did they try hard enough
to avoid risks like smoking, too much sun
or a bad diet?
Lifestyle and heredity get the most blame
but new research suggests random chance
plays a bigger role than people realize: Healthy
cells naturally make mistakes when they
multiply, unavoidable typos in DNA that can
leave new cells carrying cancer-prone genet-
How big? About two-thirds of the muta-
tions that occur in various forms of cancer
are due to those random copying errors,
researchers at Johns Hopkins University
reported Thursday in the journal Science.
Whoa: That doesn't mean most cases of
cancer are due solely to "bad luck." It takes
multiple mutations to turn cells into tumors
- and a lot of cancer is preventable, the
Hopkins team stressed, if people take prov-
en protective steps.
Thursday's report is an estimate, based on
a math model, that is sure to be hotly debat-
ed by scientists who say those unavoidable
mistakes of nature play a much smaller role.
But whatever the ultimate number, the
research offers a peek at how cancer may
And it should help with the "why me"
question from people who have "done every-
thing we know can be done to prevent can-
cer but they still get it," said Hopkins' Dr.
Bert Vogelstein, a pioneer in cancer genetics
who co-authored the study. "They need to
understand that these cancers would have
occurred no matter what they did."
GENE MUTATIONS CAUSE CANCER BUT
WHAT CAUSES THE MUTATIONS?
You might inherit some mutations, like
flaws in BRCA genes that are infamous for
causing aggressive breast and ovarian cancers
in certain families.
More commonly, damage is caused by
what scientists call environmental factors
- the assault on DNA from the world around
us and how we live our lives. There's a long
list of risks: Cigarette smoke, UV light from
the sun, other forms of radiation, certain
hormones or viruses, an unhealthy diet,
obesity and lack of exercise.
Then there are those random copy errors
in cells - what Vogelstein calls our baseline
rate of genetic mutations that will occur no
matter how healthy we live.
One way to think of it: If we all have some
mutations lurking in our cells anyway, that's
yet another reason to avoid known risks that
could push us over the edge.
HOW CELLS MAKE TYPOS
New cells are formed when an existing
cell divides and copies its DNA, one cell
turning into two. Every time DNA is copied,
about three random mutations occur, Vogel-
We all harbor these kinds of mutations
and most don't hurt us because they're in
genes that have nothing to do with cancer
or the body's defense mechanisms spot and
fix the damage, said Dr. Otis Brawley of the
American Cancer Society, who wasn't
involved in the new research.
But sometimes the errors hit the wrong
spot and damage genes that can spur can-
cerous growth or genes that help the cell
spot and fix problems. Then the damaged
cells can survive to copy themselves, allow-
ing important mutations to gradually build
up over time. That's one reason the risk of
cancer increases with age.
THE STUDY FINDINGS
Thursday's study follows 2015 research by
Vogelstein and statistician Cristian Toma-
setti that introduced the idea that a lot of
cancer may be due to "bad luck," because
those random DNA copying mistakes are
more common in some kinds of cancer than
others. Cancer prevention advocates worried
the idea might sway people to give up on
This time around, the duo analyzed muta-
tions involved in 32 types of cancer to esti-
mate that 66 percent of the gene flaws are
due to random copy errors. Environmental
and lifestyle factors account for another 29
percent, while inherited genes made up just
5 percent of the mutations.
DIFFERENT ORGANS, DIFFERENT RISKS
The same person can harbor a mix of
mutations sparked by random DNA mistakes,
heredity or environmental factors. And which
is the most common factor differs by cancer,
the Hopkins team said.
For example, they estimate that random
cell errors account for 77 percent of critical
mutations in pancreatic cancer - while still
finding some caused by lifestyle risks like
smoking. And the random DNA mistakes
caused nearly all the mutations leading to
childhood cancers, which is not surprising
because youngsters have had little time to
be exposed to environmental risks.
In contrast, most lung cancer mutations
were the result of lifestyle factors, mainly
from smoking. And while lung tissue doesn't
multiply frequently, the small number of
mutations caused by chance DNA errors
might explain rare cases of never-smokers
who still get sick.
"This paper is a good paper," said the
cancer society's Brawley. "It gives prevention
its due respect."
OTHER SCIENTISTS SEE MORE TO THE
Estimates from Britain suggest 42 percent
of cancers are potentially preventable with
a healthy lifestyle, and the Hopkins team
says their mutation research backs that idea.
But Dr. Yusuf Hannun, Stony Brook Uni-
versity's cancer center director, contends
that's just the number known to be prevent-
able today - researchers may discover addi-
tional environmental risks we can guard
against in the future.
He said the Hopkins paper exaggerates the
effect of the unavoidable DNA mistakes. His
own 2015 research concluded they account
for 10 to 30 percent of cancer cases.
GERMAN SCIENTISTS TESTING 'ARTIFICIAL SUN'
BERLIN (AP) -- Scientists in Germany
flipped the switch Thursday on what's
being described as "the world's largest
artificial sun," a device they hope will help
shed light on new ways of making cli-
The giant honeycomb-like setup of 149
spotlights - officially known as "Synlight"
- in Juelich, about 30 kilometers (19 miles)
west of Cologne, uses xenon short-arc lamps
normally found in cinemas to simulate nat-
ural sunlight that's often in short supply in
Germany at this time of year.
By focusing the entire array on a single
20-by-20 centimeter (8x8 inch) spot, sci-
entists from the German Aerospace Center,
or DLR , will be able to produce the equiv-
alent of 10,000 times the amount of solar
radiation that would normally shine on the
Creating such furnace-like conditions -
with temperatures of up to 3,000 degrees
Celsius (5,432 Fahrenheit) - is key to test-
ing novel ways of making hydrogen, accord-
ing to Bernhard Hoffschmidt, the director
of DLR's Institute for Solar Research.
Many consider hydrogen to be the fuel
of the future because it produces no carbon
emissions when burned, meaning it doesn't
add to global warming. But while hydrogen
is the most common element in the universe
it is rare on Earth. One way to manufacture
it is to split water into its two components
- the other being oxygen - using electric-
ity in a process called electrolysis.
Researchers hope to bypass the electric-
ity stage by tapping into the enormous
amount of energy that reaches Earth in the
form of light from the sun.
Hoffschmidt said the dazzling display is
designed to take experiments done in small-
er labs to the next level, adding that once
researchers have mastered hydrogen-mak-
ing techniques with Synlight's 350-kilowatt
array, the process could be scaled up ten-fold
on the way to reaching a level fit for indus-
try. Experts say this could take about a
decade, if there is sufficient industry sup-
The goal is to eventually use actual sun-
light rather than the artificial light produced
at the Juelich experiment, which cost 3.5
million euros ($3.8 million) to build and
requires as much electricity in four hours
as a four-person household would use in a
Hoffschmidt conceded that hydrogen isn't
without its problems - for one thing it's
incredibly volatile - but by combining it
with carbon monoxide produced from
renewable sources, scientists would, for
example, be able to make eco-friendly ker-
osene for the aviation industry.
SCIENCE SAYS CANCER
MAY NOT BE IN DNA:
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