Epidemiology Research Today is a free monthly online journal that collates and summarizes the latest research about Epidemiology, including details on twin studies, statistics, environmental and genetic factors.

Differences in epidemiology, histology, and survival between cigarette smokers and never-smokers who develop non-small cell lung cancer.

Bryant A, Cerfolio RJ

Division of Cardiothoracic Surgery, University of Alabama at Birmingham, 1900 University Blvd, THT 712, Birmingham, AL 35294, USA.

BACKGROUND: The impact that smoking cigarettes has on the characteristics and survival of patients with non-small cell lung cancer (NSCLC) is disputed. METHODS: A retrospective cohort study using a prospective database of patients with NSCLC over a 6-year period. Clinical and histologic characteristics and survival rates were compared between smokers and never-smokers. RESULTS: There were 730 patients; 562 patients (77%) were smokers and 168 patients (23%) were never-smokers. The overall 5-year survival rate was greater in never-smokers (64%) compared to smokers (56%; p = 0.031). Never-smokers were more likely to be younger (p = 0.04), female (p = 0.01), symptomatic at the time of presentation (p < 0.001), have poorly differentiated tumors (p = 0.04), and have a higher maximum standardized uptake value (maxSUV) on positron emission tomography (PET) (p = 0.026) than smokers. The stage-specific 5-year survival rate was greater for never-smokers compared to smokers for stage I disease (62% vs 75%, respectively; p = 0.02), stage II disease (46% vs 53%, respectively; p = 0.09), and stage III disease (36% vs 41%, respectively; p = 0.13). The 5-year survival rate was significantly lower in patients who had a smoking history of > 20 pack-years. CONCLUSIONS: Never-smokers in whom NSCLC develops are more likely to be young, female, and have poorly differentiated tumors with higher maxSUV values on PET scans. Never-smokers with early-stage cancer have a significantly better survival rate than smokers. Patients with a smoking history of > or = 20 pack-years have worse survival. Thus, smoking not only causes lung cancer, but once NSCLC is diagnosed, the prognosis becomes worse. A biological, hormonal, and genetic explanation is currently lacking to explain these findings, and these data may help to improve treatment and surveillance.

Published 12 July 2007 in Chest, 132(1): 185-92.
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