Table 4

Population-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)
Marcus, 2000 (64)1993–1996864/79020–7420+ vs. never1.1 (0.9–1.4)20+ vs. never1.3 (1.1–1.8)<15 vs. never1.5 (0.9–2.5)
Millikan, 1998 (66)1993–1995498/47320–74>20 vs. never1.1 (0.7–1.7)20+ vs. never1.6 (1.1–2.3)
Morabia, 1996 (67)1992–1993244/103230–7420+ vs. never4.6 (2.2–9.7)20+ vs. never2.9 (1.4–6.0)
Gammon, 1998 (56) b1990–19921645/1497<45>20 vs. never1.0 (0.7–1.4)>21 vs. never0.7 (0.5–0.9)>20 vs. never0.8 (0.6–1.1)≤15 vs. never0.6 (0.4–0.9)
Baron, 1996 (47)1988–19916888/9529<75>40 vs. never1.1 (0.8–1.5)50+ vs. never1.1 (0.8–1.4)≤15 vs. never1.0 (0.8–1.3)
Lash, 1999 (61)1983–1986266/765<50–8020+ vs. never1.6 (0.6–4.3)40+ vs. never2.4 (1.1–5.5)<17 vs. never2.4 (0.8–7.2)
Adami, 1988 (183)1984–1985422/527<4520+ vs. never1.1 (0.7–1.8)20+ vs. never1.2 (0.8–1.7)<15 vs. never1.3 (0.7–2.5)
Palmer, 1991 (175)1982–1986607/121435–6925–34 vs. never1.5 (0.9–2.5)40+ vs. neverc1.0 (0.5–2.1)<14 vs. never1.9 (0.9–4.4)
Ewertz, 1993, 1990 (94 , 189)1983–1984623/57825–6920+ vs. never0.8 (0.6–1.0)30+ vs. never1.0 (0.7–1.5)<15 vs. never0.9 (0.4–1.8)
Smith, 1994 (73)1982–1985755/755<3616+ vs. never1.1 (0.8–1.5)10+ vs. never1.0 (0.8–1.2)10+ vs. never1.0 (0.8–1.4)<16 vs. never1.1 (0.8–1.4)
Rohan, 1989 (185)1982–1984451/45120–74>15 vs. never1.6 (1.0–2.6)25+ vs. never1.6 (1.0–2.5)
Field, 1992 (184)1982–19841617/161720–79>40 vs. never1.2 (0.7–2.0)40+ vs. never1.2 (0.7–2.0)40+ vs. never1.1 (0.8–1.4)<20 vs. never1.0 (0.9–1.2)
Mayberry, 1994 (90)1980–1982148/16720–5411+ vs. none1.1 (0.6–1.9)
Chu, 1990 (188)1980–19824720/468220–5425+ vs. never1.2 (1.1–1.4)30+ vs. never1.1 (0.9–1.3)40+ vs. never1.1 (0.9–1.4)<17 vs. never1.1 (1.0–1.2)
O’Connell, 1987 (186)1977–1978276/1519>20 vs. never0.6 (0.3–1.1)
Stroup, 1987 (187) d1959–19604720/468220–5425+ vs. never1.2 (1.0–1.4)30+ vs. never1.1 (1.0–1.3)<15 vs. never1.1 (0.9–1.4)
  • a OR, odds ratio; CI, confidence interval.

  • b Results presented are for current smokers. Results for former smokers showed statistically non-significant positive associations with smoking.

  • c The analysis was limited to smokers of 25 or more cigarettes/day.

  • d Results presented are for current smokers. Results for former smokers were similar.