SULT1A1 genotype, active and passive smoking, and breast cancer risk by age 50 years in a German case–control study

Table 2 Odds ratios for breast cancer associated with smoking variables stratified by SULT1A1 genotype

	SULT1A11/1 genotype			SULT1A12* allele carrier^a
Variable	Cases (n = 198)	Controls (n = 374)	OR^b (95% CI)	Cases (n = 221)	Controls (n = 510)	OR^b (95% CI)
Never active	86	159	1 (ref)	88	209	1 (ref)
Ever active	112	215	0.92 (0.63–1.34)	133	301	1.01 (0.73–1.42)
Never active/passive^{c, d}	20	56	1 (ref)	19	57	1 (ref)
Former active	44	94	1.23 (0.64–2.36)	59	157	1.11 (0.60–2.06)
Current active	68	121	1.44 (0.76–2.71)	74	144	1.51 (0.82–2.78)
Average cigarettes per day^{c, e}
>0–9	42	106	1.06 (0.55–2.03)	52	154	0.99 (0.54–1.84)
10–19	56	73	2.12 (1.10–4.07)	60	99	1.75 (0.94–3.25)
20+	14	34	1.05 (0.45–2.46)	20	48	1.09 (0.51–2.32)
Duration of smoking^{c, d}
1–15 years	36	80	1.19 (0.61–2.34)	46	145	0.97 (0.52–1.82)
16+ years	76	135	1.44 (0.77–2.69)	87	156	1.62 (0.89–2.95)
Age at first cigarette^{c, d}
9–15 years	21	47	1.09 (0.51–2.35)	20	63	0.84 (0.40–1.79)
16–18 years	56	109	1.33 (0.70–2.52)	70	145	1.42 (0.77–2.62)
19+ years	35	59	1.51 (0.75–3.05)	43	93	1.42 (0.74–2.72)
Pack-years^{c, e}
>0–10	59	129	1.22 (0.65–2.27)	76	191	1.15 (0.64–2.07)
11+	53	84	1.77 (0.91–3.42)	56	110	1.43 (0.77–2.67)
Passive smoking^f
No	20	57	1 (ref)	19	57	1 (ref)
Yes	66	102	1.69 (0.89–3.21)	69	152	1.40 (0.74–2.64)
Duration of passive exposure in adulthood^{f, g, h}
1–13 years	29	40	1.91 (0.91–4.00)	33	70	1.47 (0.72–2.98)
14+ years	32	47	1.66 (0.79–3.48)	29	61	1.47 (0.70–3.10)
Cumulative lifetime exposure (in hours/day-years)^{f, g, i}
1–55	22	49	1.13 (0.52–2.38)	37	76	1.76 (0.89–3.50)
56+	43	52	2.12 (1.06–4.25)	32	71	1.39 (0.68–2.83)

^aIncludes SULT1A1*1/*2 and SULT1A1*2/*2 genotypes. ^bOdds ratios (ORs) stratified for age by 5-year intervals; additional adjustment was made for first-degree family history (yes/no), breastfeeding (total number of months) and body mass index (weight [kg]/ height [m]²) as continuous variables, parity (0, 1–2, 3+ children), alcohol consumption (0, 1–18, 19+ g/day), menopausal status (premenopausal, postmenopausal, unknown) and education (low, intermediate, high) as categorical variables. ^cReference group comprises never active/never passive smokers; category of passive smokers included in the models. ^dData missing for one control individual. ^eData missing for three control individuals and one case. ^fEver active smokers are excluded from the analysis; reference group consists of women not exposed to passive smoke. ^gDichotomization according to median of nonsmoking control individuals. ^hCategory of subjects only exposed during childhood is included in the model. ⁱSum of hours/day-years for the sources partner, work and childhood, whereby childhood hours/day-years were divided by the number of smokers to avoid overlapping of exposures; data missing for one case and six control individuals.

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