A new assessment tool uses standard clinical and epidemiologic data to predict which smokers are at highest risk for developing lung cancer, according to an article in the May 2 issue of the Journal of the National Cancer Institute.

The prediction tool, developed by researchers at the University of Texas M. D. Anderson Cancer Center, is the first designed to assign a score assessing a person's risk for the disease. It is also the first to use standard clinical and epidemiological data easily gathered by healthcare professionals, including smoking habit, exposure to environmental tobacco smoke, family history of cancer, hay fever, emphysema, and exposure to dust or asbestos.

"Our goal is to develop an instrument that can provide physicians with patients' estimated risk for developing lung cancer, like the Gail model does for breast cancer, or the Framingham model to predict heart disease," said Carol Etzel, PhD, assistant professor in the Department of Epidemiology, and the study's senior author.

The model's prediction level of lung cancer is about 60 percent, comparable with that of the Gail model, the researchers said.

The risk assessment tool was developed and tested based on research comparing the medical history of 1,851 lung cancer cases treated at M. D. Anderson with the same data from 2,001 matched healthy controls. With a population so large, the researchers were able to divide the cases and controls into two groups: the first for building the model, the second set for testing and validating the model.

This approach is the gold-standard for the development of risk assessment models, said Spitz. Current, former and never smokers were all included in the development of the model - the first time a lung cancer assessment tool has included individuals who have never smoked.

Based on the model, clinicians could compute a patient's ordinal risk score and absolute chance of developing lung cancer within a year. The patient then could be classified into the high-, moderate-, or low-risk group. Examples of key risk factors found in the targeted groups varied by smoking status. Among never smokers, exposure to secondhand smoke and family history of cancer were very important; among current and former smokers, important factors were emphysema, exposure to dust, and no history of hay fever; among former smokers: age at which they stopped smoking and a family history of cancer were important, and asbestos exposure, intensity of smoking and family history of a smoking-related cancer were important for current smokers.

Spitz and Etzel say that the most striking finding was the strong impact of a prior history of emphysema as a risk factor in both current and former smokers. In contrast, hay fever worked as a protective agent against lung cancer in both groups.

Margaret Spitz, MD, professor and chair of the Department of Epidemiology and the study's lead author, noted that although about 85 percent of lung cancers occur in smokers, less than 20 percent of life-time heavy smokers will develop lung cancer. "The challenge becomes how to identify that fraction of long-term cigarette smokers at the highest risk for the disease," she said.

"If we know who is at greatest risk for lung cancer, we can offer the most intense smoking cessation, or perhaps even offer chemo-preventive interventions. More importantly, we could intensively screen this population with modalities that might not be appropriate for the average at-risk population," said Spitz.

The study is not without limitations. One major drawback is that the model focuses only on Caucasians due to the fact that there were not enough minority patients in the cohort to build and validate the model. "We are currently working with other institutions to combine our numbers and build a model specifically for Mexican Americans and African Americans. In preliminary testing, already we are finding that while some of the risk factors are common to both groups, there are different levels of risk, so the model for Caucasians would likely not be as predictive for other populations," said Etzel.