EX-SMOKERS WHO STARTED AT YOUNG AGE SUFFER WORST DAMAGE, RESEARCHERS FIND

Cigarette smoke may have a more dire impact on young smokers than
those who pick up the habit later in life.

Researchers have found that ex-smokers who had started smoking during
adolescence have higher levels of DNA damage to their lungs and blood
- -- a known risk for lung cancer -- than ex-smokers who started smoking
as adults.

"I don't think how long you smoked and how much you smoked and how
long ago you quit are as important as how young you were when you
started," said lead researcher John Wiencke of the University of
California, San Francisco. "That factor seemed to outweigh all those
(other) things. We were very surprised."

The findings appear in today's issue of the Journal of the National
Cancer Institute.

Blood samples and nontumorous lung tissue were obtained from 143
patients who were being treated for lung cancer. Fifty-seven of the
patients were current smokers, 79 were ex-smokers and seven had never
smoked. The patients provided detailed histories of their smoking
experience, including the age at which they started and the number of
cigarettes smoked over the years.

When researchers adjusted their data on ex-smokers to compensate for
variables such as additional years of smoking, as well as the
intensity of the habit, they found that the actual age at which
smoking began was an unexpectedly significant factor.

In other words, the younger the age at which smoking began, the
greater the amount of long-term DNA damage. Highest levels of damage
were observed in individuals who began smoking between the ages of 9
and 12.

All smokers develop some level of DNA damage, and all people who quit
experience some level of DNA repair. The new finding suggests that
less repair -- or less successful repair -- occurs in people who
smoked as adolescents.

Researchers propose two possible explanations for why age might impact
smoking-related DNA changes. One possibility is that young smokers,
whose lungs are undergoing rapid growth and development, are more
susceptible to long-lasting damage. Another possibility is that very
young smokers accumulate more chemically altered DNA, known as DNA
adducts, and the body's repair mechanisms can't catch up.

"This information tells us in clearer terms than ever about the
importance of preventing smoking initiation in teens," said Dr.
Margaret Spitz, who heads the epidemiology department at the
University of Texas M.D. Cancer Center in Houston. Spitz co-authored
an editorial endorsing the study that also appears in the medical journal.