Study finds genetic changes in lungs of smokers

WASHINGTON (Reuter) Researchers said Tuesday they had found more
evidence that smoking causes genetic changes in the lungs that can
lead to cancer. They said the damage lasts for many years and affects
both current and former smokers, even those who had quit for many
years. Samples from the lungs of healthy volunteers showed damage to
the genes that look just like changes seen in cancer, they wrote in a
report in the Journal of the National Cancer Institute. Ignacio
Wistuba of the University of Texas Southwestern Medical Center in
Dallas and colleagues across the United States and in Chile and
Canada, took biopsies, or tissue samples, from 63 volunteers. ``Among
individuals with a history of smoking, 86 percent demonstrated
(genetic changes) in one or more biopsy specimens, and 24 percent
showed (changes) in all biopsy specimens,'' the researchers wrote.
``No genetic alterations were seen in nonsmokers,'' they added. The
genetic changes they saw were a loss of heterozygosity which means
one copy of a pair of genes was missing. Genes are usually found in
identical pairs. They said this damage was seen in genes known to be
involved in cancer, including the P53 gene, and said their tests
could be used as a way to detect cancer early so that could be more
effectively treated. Adi Gazdar, who led the research, said there
have been various reports of such genetic changes, and that his team
decided to look at people who had been heavy smokers smoking the
equivalent of a pack a day for 20 years. ``The most surprising thing
in the study is that in exsmokers, the changes persisted for many,
many years for 48 years,'' he said, referring to one volunteer who
had quit smoking 48 years before participating in the study. ``We
also found some change in a woman who smoked for only one year,'' he
added. ``But that doesn't mean you shouldn't stop smoking.'' Gazdar
said the damage was very slight in that woman and stressed that
people definitely reduce their risks by quitting. ``We hope we can
prevent some of the changes,'' he added. The volunteers were now
taking several drugs, including the retinoids, derivatives of vitamin
A, which have been shown to reduce genetic damage. Lung cancer is the
most common cause of cancer deaths in the United States.