title: Differences between small-cell lung cancer and non-small-cell lung cancer among tobacco smokers.
abstract: It is known that smoking increases the risk for all histological subtypes of lung cancer. To date, the factors that determine why some patients develop small-cell lung cancer (SCLC) while others develop non-small-cell lung cancer (NSCLC) remain unknown. We compared the characteristics of 774 smokers with SCLC and NSCLC diagnosed during the period January 1999 till December 2002. Multivariate logistic regression was used to estimate the odds ratio (OR) with 95% CI. Testing of linear trend across categories of pack-years was also conducted. Six hundred and sixty-five NSCLC were compared to 109 SCLC. Among SCLC, there were significantly more females (20.2% versus 12.8%), current-smokers (81.7% versus 71.9%) as well as smokers who had smoked more than 40 pack-years (75.6% versus 50.3%). Comparing SCLC with NSCLC among the men only, having smoked more than 40 pack-years was associated with a significantly elevated odds ratio (OR) of 3.71 of developing SCLC (95% CI, 1.05-13.1; p=0.041). There was a decreasing trend in OR with increasing smoking cessation period. When comparing SCLC with adenocarcinoma, the women had a higher OR of 2.37 of developing SCLC (95% CI, 1.05-5.31; p=0.037) compared to the men. Our findings suggest that cumulative smoking exposure in terms of pack-years smoked is an important determining factor for the preferred development of SCLC among smokers.
authors.affiliation: Department of Medical Oncology, National Cancer Centre, 11 Hospital Drive, Singapore 169610, Singapore. dmotck@nccs.com.sg
authors.forename: Chee-Keong
authors.initials: CK
authors.lastname: Toh
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Wan-Teck
authors.initials: WT
authors.lastname: Lim
authors.forename: Swan-Swan
authors.initials: SS
authors.lastname: Leong
authors.forename: Kam-Weng
authors.initials: KW
authors.lastname: Fong
authors.forename: Swee-Peng
authors.initials: SP
authors.lastname: Yap
authors.forename: Anne A L
authors.initials: AA
authors.lastname: Hsu
authors.forename: Philip
authors.initials: P
authors.lastname: Eng
authors.forename: Heng-Nung
authors.initials: HN
authors.lastname: Koong
authors.forename: Agasthian
authors.initials: A
authors.lastname: Thirugnanam
authors.forename: Eng-Huat
authors.initials: EH
authors.lastname: Tan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000139:chemically induced / Q000473:pathology*; D018288:Carcinoma, Small Cell / Q000139:chemically induced / Q000473:pathology*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012189:Retrospective Studies; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors; D014026:Nicotiana