Table 5.

Interactions between Occupational EC Exposure and Smoking for Overall Lung Cancer and Major Subtypes in Men

Exposure Status by Lung Cancer Subtype	Controls	Cases	OR*	95% CI
All lung cancers
Never-smoker and never EC	2,525	256	1.0	Referent
Never-smoker and ever EC	1,912	234	1.14	0.95–1.38
Ever-smoker and never EC	5,745	5,304	8.71	7.62–10.0
Ever-smoker and ever EC	6,269	7,811	11.4	9.93–13.0
P multiplicative†	—	—	0.18	—
RERI‡	—	—	2.49	1.92–3.07
Adenocarcinoma
Never-smoker and never EC	2,525	100	1.0	Referent
Never-smoker and ever EC	1,912	79	1.05	0.77–1.42
Ever-smoker and never EC	5,745	1,413	6.14	4.99–7.63
Ever-smoker and ever EC	6,269	1,733	7.22	5.87–8.98
P multiplicative†	—	—	0.47	—
RERI‡	—	—	1.03	0.43–1.63
Large cell carcinoma
Never-smoker and never EC	2,525	14	1.0	Referent
Never-smoker and ever EC	1,912	5	0.43	0.14–1.14
Ever-smoker and never EC	5,745	243	7.57	4.57–13.7
Ever-smoker and ever EC	6,269	357	9.35	5.66–16.8
P multiplicative†	—	—	0.05	—
RERI‡	—	—	2.34	0.67–4.02
Squamous cell carcinoma
Never-smoker and never EC	2,525	64	1.0	Referent
Never-smoker and ever EC	1,912	77	1.38	0.98–1.94
Ever-smoker and never EC	5,745	2,152	13.4	10.5–17.1
Ever-smoker and ever EC	6,269	3,535	18.1	14.4–24.0
P multiplicative†	—	—	0.99	—
RERI‡	—	—	4.66	3.23–6.09
Small cell carcinoma
Never-smoker and never EC	2,525	26	1.0	Referent
Never-smoker and ever EC	1,912	30	1.38	0.81–2.36
Ever-smoker and never EC	5,745	824	13.5	9.32–20.6
Ever-smoker and ever EC	6,269	1,320	18.5	12.8–28.1
P multiplicative†	—	—	0.96	—
RERI‡	—	—	4.56	2.42–6.69

Definition of abbreviations: CI = confidence interval; EC = elemental carbon; OR = odds ratio; RERI = excess risks due to interaction.

^*ORs adjusted for study, age group, and list A jobs.

^†P value for the EC and smoking interaction cross product term coefficient in fully adjusted logistic models; interaction on the multiplicative scale is present when P < 0.05.

^‡Interaction on the additive scale is present when RERI deviates from 0.