December 3, 2008
Albuquerque Journal
SMOKING'S GENETIC SHIELD?
By Amanda Schoenberg, Journal Staff WriterHispanic female smokers in New Mexico may be less likely to develop chronic smoking-related breathing problems than non-Hispanic white women even if they smoked for the same number of years, scientists reported in a recent study.
Researchers said the link between ethnicity and smoking-related breathing problems could eventually pave the way for a better understanding of chronic obstructive pulmonary disease, the fourth-leading cause of death in the United States, according to the Centers for Disease Control and Prevention.
The five-year study, supported by the Tobacco Settlement Commission of New Mexico, was published last month in the Journal of Chronic Obstructive Pulmonary Disease. It included 1,433 former or current smokers ages 40 to 75 in Albuquerque. Just more than 17 percent, or 248, of the participants were Hispanic women. The rest were non-Hispanic white women. All had smoked at least 20 years.
Results indicated that when scientists adjusted factors like socioeconomic background, age, current smoking status and number of years spent smoking, Hispanic female smokers were half as likely as Anglo women in New Mexico to experience airflow obstruction in their lungs.
Scientists cautioned that these kind of ethnic differences shouldn't put any smokers at ease. Even if smokers don't develop COPD, the many other risks of smoking, such as heart disease and lung cancer, remain significant, said Dr. Norman Edelman, chief medical officer at the American Lung Association.
"The next question is, what is it about Hispanics that protects them?" said study author Dr. Akshay Sood, an associate professor of medicine at the University of New Mexico.
"Understanding susceptibility is the most important thing to finding treatment."
But what causes the difference remains unclear, said Dr. Yohannes Tesfaigzi, director of the COPD institute at Lovelace Respiratory Research Institute, another of the study authors.
Behavioral differences are one possibility. For example, Tesfaigzi said Hispanic female smokers may inhale less than non-Hispanic white females even if they reported smoking the same amount of years.
The answer may also be genetic. About 26 percent of smokers develop COPD, an umbrella syndrome that includes emphysema and chronic bronchitis, Tesfaigzi said. But there is little understanding of why some smokers develop COPD and some don't, he said.
A 2001 study in the American Journal of Respiratory and Clinical Care Medicine found that among smokers, if one sibling had COPD, the other was more likely to develop it. Tesfaigzi is now studying specific genes to find out why some people are more susceptible to COPD.
"It is somehow genetic," Tesfaigzi said. "The big search right now is which genes?"
Edelman said the New Mexico study results warrant more research. COPD research has often been neglected, he said.
"It is one of the major causes of death that is increasing rather than decreasing," he said. "It's an enormous worldwide problem. COPD to a large extent has been ignored, as has lung cancer."
According to Edelman, the "reflex response" to the New Mexico study would be to attribute the difference in airflow obstruction between Hispanic and Anglo female smokers to genetics. But Edelman cautioned that factors like diet, location and proximity to secondhand smoke might be at work.
He noted that Hispanic men are less likely to smoke than non-Hispanic white men. That means Hispanic women might be less exposed to secondhand smoke than non-Hispanic white women.
Ethnic differences have emerged in prior COPD research, Edelman said. But the New Mexico study appears to be the first to look specifically at differences between non-Hispanic white and Hispanic female smokers, according to Sood and Tesfaigzi.
More studies should examine ethnic and gender differences in COPD especially as smoking patterns change, the scientists said. Between 2000 and 2005, smoking was responsible for about 75 percent of COPD deaths, the CDC reported. In the same period, the number of women who died from COPD rose by 11 percent while the number of men increased by 5 percent. Although the death rate was higher for men every year, nearly 6,000 more women than men died from COPD in 2005, according to the CDC.
According to Sood, the New Mexico study follows work in the 1980s by epidemiologist Jonathan Samet, who found that fewer Hispanic than Anglo smokers in New Mexico died from COPD. The current study measured smokers' breathing abilities to follow up on that data, Sood explained.
Tesfaigzi cautions that the recent New Mexico study included a relatively small sample size. Results point to the need for larger study groups that can link gender, ethnicity and COPD, he said.
"This is just one observation. We would like to see other studies," Tesfaigzi said.