Table 2

Hospital-based case-control studies of cigarette smoking and breast cancer risk

First author, study yearYears of data collectionNo. of cases/controlsAge range (yrs)Smoking frequency (cigarettes/day)Smoking duration (yrs)Pack-years (packs/day × years)Age smoking commenced (yrs)
ComparisonOR (95% CI)aComparisonOR (95% CI)ComparisonOR (95% CI)ComparisonOR (95% CI)
Braga, 1996 (49)1991–19942569/258820–7425+ vs. never1.2 (0.8–1.7)30+ vs. never1.0 (0.8–1.2)<16 vs. never1.0 (0.8–7.1)
Palmer, 1991 (175)1982–19861955/80530–6935+ vs. never1.1 (0.7–1.8)40+ vs. neverb1.7 (0.9–3.3)<14 vs. never2.4 (0.9–4.4)
Stockwell, 1987 (177)19815246/3921<50–75>40 vs. non-smokers1.3 (1.0–1.8)
Rosenberg, 1984 (176)1976–19822160/71730–6925+ vs. never1.1 (0.8–1.6)
Baron, 1986 (182)1957–19651741/212840–8915+ vs. never0.9 (0.8–1.1)
  • a OR, odds ratio; CI, confidence interval.

  • b Analysis was limited to smokers of 25 cigarettes/day or more.