Among individuals who develop lung cancer, there appear to be differences between smokers and nonsmokers in survival rates and in individuals patient characteristics, researchers report. They say the findings indicate that lung cancer in nonsmokers is a specific disease, which has implications for research and clinical trials.

Dr. George R. Simon and colleagues from the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Florida, analyzed patient characteristics and survival rates in 132 individuals who never smoked and in 522 current smokers diagnosed with primary lung cancer.

They observed that never-smokers were generally older at diagnosis (63.5 years versus 59.4 years) and more often female (78 percent versus 54 percent). Also, never-smokers had better overall survival rates than current smokers, with survival estimates at 5 years of 23 percent versus 16 percent.

After adjusting for other risk factors, smoking was an “independent negative prognostic factor,” the investigators report in the medical journal Chest.

Commenting on these findings, Simon told Reuters Health that lung cancer in smokers is the result of the “carcinogenic properties of chronic tobacco use.” In contrast, lung cancer in never-smokers occurs without exposure to the carcinogenic properties of tobacco. Therefore, lung cancer in nonsmokers has a distinct behavior and survival rate.

Lung cancer in never-smokers “is a different disease in itself, with its own unique biology, behavior characteristics, and survival,” Simon concluded. “Therefore, we assert that laboratory and clinical investigations be specifically designed to further study this distinct disease entity.”

Dr. Peter J. Mazzone and two colleagues from The Cleveland Clinic Foundation in Ohio concur, noting in an editorial in Chest that this study “further highlights the importance of stratification of patients for smoking history in future clinical trials.”

SOURCE: Chest, August 2004.