Table 4 Relative risks (RR; 95 CI) for lung cancer by histological type, from the polytomous logistic regression model 1 comparing risks associated with current and former smoking, Nurses’ Health Study, 1976–2002: final model with corresponding p values for the differences between the histological types
Histological type
Squamous cell carcinomaSmall cell carcinomaAdenocarcinomaLarge cell carcinomap Value*
Age (year)1.15 (1.13 to 1.18)1.14 (1.12 to 1.16)1.13 (1.11 to 1.14)1.09 (1.06 to 1.11)<0.001
Age at smoking initiation (year)†0.95 (0.93 to 0.96)–––0.10
Cigarettes/day (current) (per cig)†1.05 (1.05 to 1.06)–––0.15
Cigarettes/day (former) (per cig)†1.05 (1.04 to 1.06)–––0.21
Years since quitting (per year)0.89 (0.87 to 0.91)0.83 (0.80 to 0.86)0.92 (0.91 to 0.94)0.91 (0.88 to 0.94)<0.001

  • *p Value for test of heterogeneity. –, value from previous column applies. †Value in first column is estimate for all histological types combined.