Table 4. Association between main hormonal factors and lung cancer risk: analyses stratified by smoking status.

	Never smokers					Former smokers					Current smokers
	Cases	Controls	OR	95% CI	P	Cases	Controls	OR	95% CI	P	Cases	Controls	OR	95% CI	P	Pfor interaction
OC
Never	195	585	1			253	230	1			363	193	1
Ever	128	585	0.89	(0.65–1.21)	0.5	338	368	0.72	(0.52–1.00)	0.05	489	347	0.88	(0.65–1.20)	0.4	0.4
Missing	21	81				80	67				83	118
HRTa
Never	194	527	1			349	270	1			527	284	1
Ever	104	438	0.73	(0.54–0.98)	0.04	268	292	0.77	(0.59–1.01)	0.06	326	258	0.85	(0.65–1.12)	0.2	0.3
Missing	3	2				5	2				7	0
HRT typeb
Never Users	105	292	1			250	170	1			313	211	1
Oestrogen only	45	154	0.94	(0.61–1.46)	0.8	111	119	0.65	(0.46–0.94)	0.02	115	124	0.78	(0.54–1.12)	0.2	0.6
E+P only	20	100	0.52	(0.28–0.95)	0.03	45	63	0.61	(0.35–1.04)	0.07	72	68	0.97	(0.60–1.55)	0.9	0.2
Missing	12	54				45	38				63	27

Abbreviations: CI=confidence interval; E+P=oestrogen+progesterone; HRT=hormone replacement therapy; OC=oral contraceptive; OR=odds ratio.

Effect estimates are expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs).

Logistic regression model adjusted for age at interview (categorical), ethnicity (Caucasian/non-Caucasian), comprehensive smoking index (CSI; continuous), body mass index (BMI; continuous), education (categorical) and study.

^aIn postmenopausal women only.

^bOnly available in MLCS, TORONTO and WELD.