Jan. 4, 2000 (Lake Worth, Fla.) -- Smoking may be more devastating for women
Jan. 4, 2000 (Lake Worth, Fla.) -- Smoking may be more devastating for women than previously thought. Researchers at the University of Pittsburgh have identified a genetic marker that may be the first biological explanation for why women appear to have a higher risk than men of developing lung cancer.
"We were looking at this gene that we knew was involved in lung cancer, and it was a really early step in the development of lung cancer," Sharon Persinger Shriver, PhD, a co-author of the study, tells WebMD. "And we began looking at the genetics and biology of it and found it was on the X chromosome." The genetic marker, the gastrin-releasing peptide receptor (GRPR), is found on the surface of the cells lining the lung. When activated, it triggers the types of cells seen most often in lung cancer.
"This is one of the very small number of genes where women have 2 copies of the gene that could be activated, or expressed," Shriver says. Shriver is now professor of biology at the University Park campus of Pennsylvania State University.
The researchers, whose study appears in the Jan. 5 issue of the Journal of the National Cancer Institute, looked at the normal lung tissue from 38 women and 40 men, 58 of whom had lung cancer. Among the non-smoking women sampled, 55% expressed GRPR; 75% of women with less than 25 pack-years of smoking expressed the genetic marker. Among the male non-smokers sampled, researchers found they didn't express the gene at all. Twenty-percent of the males who had 25 or less pack-years of smoking showed signs of expression.
A pack-year is the number of packs of cigarettes smoked per day multiplied by years of smoking. For example, 2 packs a day for 10 years is 20 pack-years.
Shriver said her group looked at a few more ways the GRPR was activated and found that nicotine could be identified as a culprit. "It still doesn't really explain the expression in female nonsmokers, but that may be because they have two copies of the gene." However, knowing that the gene expresses in nonsmokers, may help identify who is at risk for lung cancer and explain why among nonsmokers who develop lung cancer, three times more are women.
"The only segment of the population that has an increasing rate of smoking is young women, " David Yankelevitz tells WebMD. Yankelevitz, who was not connected with Shriver's study, was part of the research team at Cornell University that developed the Early Lung Cancer Action Program (ELCAP).
The ELCAP study found that more women than men, unrelated to smoking category or age, developed lung cancer. Yankelevitz is a professor of radiology at Weill School of Medicine at Cornell University, in New York.
Besides being what Shriver calls a heads-up message to women, especially teen girls, to quit smoking -- or better yet, never start -- she feels the identification of a marker, once a test is available for it, could lead to earlier detection.
"The only real chance to cure lung cancer is early detection," Yankelevitz says. "This is where these markers are going to be very useful to guide us in terms of how often to screen, what to look for. That's the value of this and I think there will be a host of other markers that will be found in the not too distant future."
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Vital Information:
- Researchers have found a gene on the X chromosome that increases the risk of lung cancer.
- This may be the first biological explanation of why women have a greater risk of developing lung cancer than men, since they carry two copies of the gene instead of one.
- A researcher says the discovery should encourage women, especially teen-agers, to stop smoking or never start.
Vital Information:
- Researchers have found a gene on the X chromosome that increases the risk of lung cancer.
- This may be the first biological explanation of why women have a greater risk of developing lung cancer than men, since they carry two copies of the gene instead of one.
- A researcher says the discovery should encourage women, especially teen-agers, to stop smoking or never start.
