title: Gender, histology, and time of diagnosis are important factors for prognosis: analysis of 1499 never-smokers with advanced non-small cell lung cancer in Japan.
abstract: BACKGROUND
  There has been a growing interest in lung cancer in never-smokers.
  
  
  METHODS
  Utilizing a database from the National Hospital Study Group for Lung Cancer, information for never-smokers and ever-smokers with advanced non-small cell lung cancer was obtained from 1990 to 2005, including clinicopathologic characteristics, chemotherapy response, and survival data. Time of diagnosis was classified into two periods: 1990-1999 and 2000-2005. Multivariate analysis was performed using the Cox regression and logistic regression method, including gender, age, performance status, histology, stage, and period of diagnosis.
  
  
  RESULTS
  There were 1499 never-smokers and 3455 ever-smokers with advanced stage IIIB and IV diseases who received cytotoxic chemotherapy. Never-smokers generally included more females, were younger, with better performance status and more adenocarcinoma diagnosed (p < 0.0001 for all). Smoking status was a significant prognostic factor (never-smoker versus ever-smoker; hazard ratio [HR] = 0.880, 95% confidence interval [CI]: 0.797-0.970; p = 0.0105). In separate multivariate analysis for never-smokers and ever-smokers, female gender and better performance status (p < 0.0001 for both) were both favorable prognostic factors. However, adenocarcinoma histology (versus squamous cell carcinoma; HR = 0.790, 95% CI: 0.630-0.990; p = 0.0403) and the period after 2000 (versus before 2000; HR = 0.846, 95% CI: 0.731-0.980; p = 0.0254) were significant only in the never-smokers, and younger age (HR = 1.007, 95% CI: 1.003-1.011; p = 0.0010) was significant only in the ever-smokers. In an exploratory analysis, different profiles were observed in predictive factors for chemotherapy response between the two groups.
  
  
  CONCLUSIONS
  Never-smokers with non-small cell lung cancer lived longer than ever-smokers. Gender, histology, and time of diagnosis are important factors for prognosis in these patients.
authors.affiliation: National Hospital Organization Kinki-Chuo Chest Medical Center, Sakai, Osaka, Japan. t-kawaguchi@kch@hosp.go.jp
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: Minoru
authors.initials: M
authors.lastname: Takada
authors.forename: Akihito
authors.initials: A
authors.lastname: Kubo
authors.forename: Akihide
authors.initials: A
authors.lastname: Matsumura
authors.forename: Shimao
authors.initials: S
authors.lastname: Fukai
authors.forename: Atsuhisa
authors.initials: A
authors.lastname: Tamura
authors.forename: Ryusei
authors.initials: R
authors.lastname: Saito
authors.forename: Masaaki
authors.initials: M
authors.lastname: Kawahara
authors.forename: Yosihito
authors.initials: Y
authors.lastname: Maruyama
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000628:therapy; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D018307:Neoplasms, Squamous Cell / Q000175:diagnosis* / Q000628:therapy; D011879:Radiotherapy Dosage; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult