African American-specific Lung Cancer Risk Model Developed

Risk models for lung cancer have been largely developed in white populations. A newly developed model looks at risk factors specific to African American populations and finds some differences.

“We were doing some basic epidemiological work on our group of lung cancer cases and controls,” says Carol Etzel, PhD, professor of epidemiology at UT M.D. Anderson Cancer Center in Houston, Texas. “When we stratified them by ethnicity, we found that even though some risk factors were the same across groups, the exposure risk levels tended to be different. For example, smoking exposure among African Americans was lower, but still they had higher risks of lung cancer when compared to whites.”

Etzel and her colleagues then took a model they had recently published from a white cohort and applied it to their African American group. They found that it did not perform very well discriminating who would get lung cancer and who would not.

“These two things made us realize that we may need a risk model that is specific to African Americans to take into account those different levels of risk and exposure,” Etzel says.

The researchers analyzed data from 491 African Americans with lung cancer and 497 matched controls from the Anderson Cancer Center and the Michael E. DeBakey VA Medical Center, both in Houston. They used this cohort to identify African American-specific risk factors for the disease and estimated the absolute 5-year risk for lung cancer. They then validated the models using another group from Houston and data from two different cancer studies in Detroit.

The final risk model included smoking-related variables such as status, pack-years smoked, age at cessation for former smokers, and number of years since they stopped smoking. Other factors involved were self-reported physician diagnosis of chronic obstructive pulmonary disease (COPD) or hay fever and exposure to asbestos or wood dusts.

“We found that our African American model had a much higher discriminatory power than using the white model alone,” says Etzel. “This means that we have more sensitivity and more specificity to our African American-specific model applied to an African American group than a model developed using case-controls of a different race.”

Currently, the group is developing a Web-based tool so that physicians and others would have it readily available when needed. Although it is not known when this will go “live,” Etzel notes that the information from the article can be used immediately in the office to assess an individual’s risk.

“The risk model takes into account the underlying incidence rate for lung cancer among African Americans of both genders,” she says. “All one needs to find the 5-year risk of lung cancer would be the model from the publication and a hand-held calculator.”

John Ruckdeschel, MD, president and chief executive officer of the Barbara Ann Karmanos Cancer Institute in Detroit says that it has been established that there are differences in risk factors between the various ethnic groups. He was not involved in the study.

“It is very clear that there is a significant genetic component to lung cancer and when you have a patient in a family that develops lung cancer, all of the smokers’ risks go up and it goes up even more for African Americans than for whites,” Ruckdeschel says. “We are suggesting that those in this very unique group of individuals consider getting a CAT scan even though most insurance companies won’t pay for it.”

He thinks that it is not surprising that there would be different risk factors for different groups. Noting that there are diseases and risks that are unique to sub-populations of whites, he sees no reason why there wouldn’t be diseases that are unique or uniquely worse to African Americans.

“There is no question that between whites, African Americans, and other groups, there are differences in risk factors,” says Ruckdeschel. “One of the things driving that is race.”

- Etzel CJ, et al. Development and validation of lung cancer risk prediction model for African-Americans. Cancer Prev Res. 2008;1:255-265.

Kurt Ullman is a veteran freelance health and medical writer based out of Indianapolis.