Table 5

Prospective cohort studies of cigarette smoking and breast cancer risk

First author, study yearYears of data collectionNo. of cases/no. in cohortAge range (yrs)Smoking frequency (cigarettes/day)Smoking duration (yrs)Pack-years (packs/day × years)Age smoking commenced (yrs)
ComparisonRR (95% CI)aComparisonRR (95% CI)ComparisonRR (95% CI)ComparisonRR (95% CI)
Zheng, 1999 (76)1986273/65755–6915+ vs. noneb1.1 (0.7–1.6)
Calle, 1994 (51) c1982–1986800/60441230–70+40+ vs. never1.7 (1.2–2.6)40+ vs. never1.4 (1.1–1.8)<16 vs. never1.6 (1.2–2.2)
Terry, 2002 (195)1980–19852552/8983540–5940+ vs. never1.3 (1.1–1.7)40+ vs. never1.6 (1.2–2.2)40+ vs. never1.4 (1.2–1.6)<16 vs. never1.1 (0.9–1.4)
Egan, 2002 (84)19823140/7820636–6140+ vs. never1.1 (0.9–1.2)<17 vs. never1.2 (1.0–1.4)
Manjer, 2001 (63)1974–1992268/1090225–7520+ vs. never1.3 (1.0–1.8)
Vatten, 1990 (196)1974–1978242/2432935–5110+ vs. none0.9 (0.6–1.2)
Hiatt, 1988 (194)1979–1984303/6867440+ vs. never1.2 (0.5–2.8)
Hunter, 1997 (58)1976466/466d30–5515+ vs. nevere1.6 (1.0–2.4)30+ vs. never1.3 (0.9–1.9)
London, 1989 (192)19761788/11755730–5525+ vs. never1.0 (0.9–1.2)<17 vs. never1.1 (0.9–1.3)
Hiatt, 1986 (193)1964–19721363/8417220–84“heavy” vs. never1.2 (0.9–1.6)
Schatzkin, 1989 (191)1949–1988143/263631–6420+ vs. none1.0 (0.6–1.7)
Nordlund, 1997 (79)1963170/2600018–6916+ vs. never1.1 (0.7–1.7)<19 vs. never1.2 (0.8–1.8)
  • a RR, relative risk; CI, confidence interval.

  • b Results presented are for smokers of 25 years or longer.

  • c The endpoint examined was breast cancer mortality.

  • d This study was of nested case-control design (the numbers represent cases/controls).

  • e Results presented are for smoking 10 years prior to diagnosis (results for smoking at interview were essentially the same).