Why only some former smokers develop lung cancer

November 17, 2008

Canadian researchers are trying to answer why some smokers develop lung cancer while others remain disease free, despite similar lifestyle changes.

Results were presented at the American Association for Cancer Research's Seventh Annual International Conference on Frontiers in Cancer Prevention Research.

According to the Centers for Disease Control and Prevention, more people die from lung cancer than any other cancer type. In fact, according to 2004 data, more people died from lung cancer than breast, prostate and colon cancers combined.

Smoking is the biggest risk factor for developing lung cancer, even after quitting for long periods of time. "More than 50 percent of newly diagnosed lung cancer patients are former smokers," said Emily A. Vucic, a graduate student at the British Columbia Cancer Research Centre, Vancouver, B.C. "Understanding why some former smokers develop lung cancer is clearly important to the development of early detection, prevention and treatment strategies."

The researchers studied how DNA methylation contributes to lung cancer development in former smokers. Methylation is an important event regulating gene expression during normal development. As we age and in cancer, proper patterns of DNA methylation become deregulated throwing off the tight control of gene activity that normally exists.

Using an endoscope, Vucic and colleagues collected bronchial epithelial cells, which are cells that line the lungs, from 16 former smokers. The participants quit smoking more than 10 years ago. Eight participants had surgical removal of non-small cell lung cancer; eight were disease free.

Their results showed differences in methylation levels in lung epithelial cells between former smokers with and without lung cancer.

"Alteration to DNA methylation might potentially explain why some former smokers sustain additional genetic damage resulting in lung cancer," Vucic said. "As methylation is a reversible DNA modification, this knowledge could prompt the development and application of chemopreventive agents and unique therapeutic strategies that target DNA methylation in these patients."

Exposure to cigarette smoke is a major culprit in disease development. "In addition to DNA sequence mutations, cigarette smoke also causes widespread errors in DNA marks, such as DNA methylation, used to regulate gene function and genome stability," Vucic said.

Cigarette smoke exposure has been shown to activate genes that promote cancer and deactivate genes that stop tumor growth, she said. "Studies examining tumors at all levels of DNA disruption will identify events involved in lung cancer development in former smokers."

The researchers are pursuing additional studies to confirm their initial results, Vucic said.

Source: American Association for Cancer Research

Explore further: New way to find DNA damage: Chemists look for precursors to disease mutations

Related Stories

Researchers unveil DNA-guided 3-D printing of human tissue

August 31, 2015

A UCSF-led team has developed a technique to build tiny models of human tissues, called organoids, more precisely than ever before using a process that turns human cells into a biological equivalent of LEGO bricks. These ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Nov 17, 2008
Not all smokers develope cancer! Variations include: "How and where the tobacco was raised", "Soil and fertilizer content of crop", "Seed source and treatment of same", "Wild
or commercial crop" etc.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.