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Table 7
Studies assessing the association of maternal or paternal smoking and the risk of breast cancer
Type of study	Ref.	Year	Design	Cases	Controls (or cohort)	Country/place of study	Smoking status	OR (95% CI)	Comments

Case-control studies	[69]	1996	PCC	53	470	USA	Maternal smoking		Crude ORs
							No	Referent
							Yes	0.9 (0.4–2.1)
							Paternal smoking
							No	Referent
							Yes	1.3 (0.9–1.7)
	[14]	1996	PCC	1,086	1,321	USA	Maternal smoking		Adjusted for age, menopausal status, and maternal smoking; OR (95% CI) for maternal smoking among early-onset breast cancer patients (≤ 30 years old) was 1.9 (1.0–3.4)
							Age 21–45 years
							No	Referent
							Yes	1.1 (0.9–1.3)
							Age 50–64 years
							No	Referent
							Yes	1.3 (0.9–2.1)
	[58]	1997	PCC	522	484	USA	Maternal smoking		Adjusted for age, study site, family history of breast cancer, breast biopsy, a combination variable including number of full-term births and age at first full-term pregnancy, age at menarche, menopausal status, body mass index, average lifetime alcohol consumption, and the number of mammograms
							No	Referent
							Yes	1.1 (0.8–1.4)
	[33]	1998	PCC	507	433	USA	Maternal smoking		Crude ORs
							No	Referent
							Yes	1.1 (0.9–1.5)
	[43]	2001	LCC	319	768	USA	Maternal smoking		Adjusted for attained age
							No	Referent
							Yes	2.7 (1.1–6.3)
	[35]^a	2002	PCC	1,535	1,534	USA	Smoking		Adjusted for age and residential regions (states)
							No	Referent
							Paternal smoking	1.00 (0.88–1.13)
							Maternal/parental smoking	1.10 (0.84–1.42)
	[20]	2005	PCC	2380	2,497	Poland	Maternal smoking		Unadjusted; recalculated
							No	Referent
							Yes (any exposure)	1.19 (0.97–1.47)
							Paternal smoking
							No	Referent
							Yes (any exposure)	0.90 (0.77–1.05)
Cohort studies	[31]	2006	Cohort	249	1,024	USA	Maternal smoking	Referent	Adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age Crude relative rates
							No	0.8 (0.5–1.1)
							Yes (any exposure)
	[68]	2005	Cohort	42	(3,989)	USA	Maternal smoking
							No	Referent
							Yes (any exposure)	0.49 (0.29–1.03)
							≤ 15 cigarettes a day	0.33 (0.12–0.94)
							>15	0.68 (0.26–1.73)

^aTitus-Ernstoff and coworkers [35] classified three categories: nonparental smoking, either paternal or maternal smoking only or both parents smoking during pregnancy. Thus, in this study, the maternal or both parents smoking versus nonparental smoking can be regarded as maternal smoking versus no maternal smoking. Cohort, cohort study; LCC, case-control study by linkage with population data and cancer registry data; PCC, population-based case-control study.
Park et al. Breast Cancer Research 2008 10:R8 doi:10.1186/bcr1850

Table 7