Abstract
Introduction: Smoking and non-smoking lung cancer have many differences in clinical feature. But those may be the result of interference due to differences in pathological type, as most smoking patients suffer squmous cell lung cancer and non-smokings tend to get adenocarcinoma. This study was conducted on the specific histological type-lung adenocarcinoma-to avoid histological bias and to reveal the true effect of smoking. Methods: A total of 2222 patients with lung adenocarcinoma confirmed by histological or cytological evidence were enrolled from January 1, 1999 to December 31, 2004. Differences in clinical features and prognosis between non-smoking and smoking patients were analyzed.Chisquare test was used for univariate comparisons. Univariate probability of survival was computed using Kaplan-Meier estimate and compared to using the log-rank test. Cox proportional hazards regression analysis was used to evaluate the risk of death. Results: There were 777 current smokers (34.96%), 197 former smokers (8.87%) and 1248 non-smoking patients (56.17%). 860 non-smoking patients (68.91%) were female, compared with 6.31% among current smokers and 4.06% among former smokers (p < 0.001). Non-smoking patients had an earlier age at diagnosis (p < 0.001) and a better response to chemotherapy (p < 0.001) compared to current smoking patients. Current smoking correlated with lower cell differentiation (p < 0.001) and worse prognosis (p = 0.0024). After multivariate analysis, smoking was identified as an independent negative prognostic factor (HR, 1.302; 95% CI, 1.011 - 1.6780, p = 0.041). No difference in prognosis was observed according to smoking conditions in smoking patients. Conclusions: Significent differences exist in clinical features and prognosis between non-smoking and smoking lung adenocarcinoma patients. There is a strong evidence that non-smoking lung adenocarcinoma should be regard as different disease.
Highlights
Smoking and non-smoking lung cancer have many differences in clinical feature
When chemotherapy was performed as initial treatment in advanced patients (Stage IIIB and IV), the clinical response after four cycles to first-line chemotherapy were recorded as four levels: Complete Response (CR), Partial Response (PR), Stable Disease (SD) and Progress Disease (PD), according to RECIST critical
Operations were preformed in 503 current smokers (64.74%), 153 former smokers (77.66%) and 794 never smokers (63.62%)
Summary
Smoking and non-smoking lung cancer have many differences in clinical feature. Differences in clinical features and prognosis between non-smoking and smoking patients were analyzed. Conclusions: Significent differences exist in clinical features and prognosis between non-smoking and smoking lung adenocarcinoma patients. Smoking lung cancer patients have many differences in gender distribution, clinical features, pathology result and molecular mechanism comparing to non-smoking lung cancer [4,5]. Non-smoking lung cancer have a higher rate of mutation in Epidermal growth factor receptor (EGFR) and a better response to the EGFR Tyrosine Kinase Inhibitor: Gifitinib and Erlotinib [9,10], while have less mutations in P53 compared with smoking lung cancer [4,11]. Many scholarssuggested that lung cancer in never smokers is a “different” disease, with a different aetiology and a different natural history [5,6]
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