Table 3.

Odd Ratios for Cigar Smoking and Head and Neck Cancer in the International Head and Neck Cancer Epidemiology Consortium, 1981–2007

Variable	Cigar Smoking
	Never Cigarette Smoking				Ever Cigarette Smoking
	No. of Cases	No. of Controls	ORa	95% CI	No. of Cases	No. of Controls	ORb	95% CI
Tobacco smokingc
Never	1,567	6,824	1.00	Referent	10,525	9,759	1.00	Referent
Ever	171	155	2.54	1.93, 3.34	779	814	0.90	0.78, 1.02
Missing	1	4			15	14
Smoking frequency (cigars per day)
Never	1,567	6,824	1.00	Referent	10,525	9,759	1.00	Referent
1–10	130	136	1.99	1.47, 2.71	550	618	0.89	0.77, 1.03
>10	39	14	10.13	4.96, 20.67	184	155	0.99	0.74, 1.32
Missing	3	9			60	55
Ptrendd			<0.0001				0.62
Smoking duration, years
Never	1,567	6,824	1.00	Referent	10,525	9,759	1.00	Referent
1–10	19	52	0.91	0.51, 1.62	331	391	0.77	0.64, 0.92
11–20	18	19	2.42	1.18, 4.95	114	130	1.04	0.77, 1.42
21–30	18	24	1.92	0.95, 3.85	99	113	0.98	0.70, 1.36
31–40	43	29	3.78	2.18, 6.55	91	78	1.20	0.83, 1.72
>40	68	27	5.62	3.29, 9.60	123	87	1.04	0.73, 1.48
Missing	6	8			36	29
Ptrend			<0.0001				0.63
Cumulative cigar-years
Never	1,567	6,824	1.00	Referent	10,525	9,759	1.00	Referent
1–10	18	44	0.96	0.52, 1.77	162	245	0.71	0.56, 0.90
11–20	20	41	1.15	0.63, 2.11	226	228	0.99	0.79, 1.23
>20	127	64	4.87	3.36, 7.06	337	296	1.01	0.82, 1.25
Missing	7	10			69	59
Ptrend			<0.0001				0.05

Abbreviations: CI, confidence interval; OR, odds ratio.

^a Cigar smoking odds ratios among never cigarette smokers were adjusted for sex, age, race, educational level, frequency of alcohol use (mL of ethanol per day), and duration of pipe smoking (in years). Individuals missing the main variable or 1 or more covariates were dropped from the models. The most frequently missing variable was frequency of alcohol use. For the model of “ever” smoking, 276 individuals were not included; for the model of frequency of smoking, 283 individuals were not included; for the model of duration of smoking, 285 individuals were not included; and for the model of cigar-years, 288 individuals were not included.

^b Cigar smoking odds ratios among ever cigarette smokers were adjusted for sex, age, race, educational level, frequency of alcohol use (mL of ethanol per day), duration of cigarette smoking (in years), and duration of pipe smoking (in years). Individuals missing the main variable or 1 or more covariates were dropped from the models. The most frequently missing variable was frequency of alcohol use. For the model of “ever” smoking, 1,101 individuals were not included; for the model of frequency of smoking, 1,172 individuals were not included; for the model of duration of smoking, 1,127 individuals were not included; and for the model of cigar-years, 1,184 individuals were not included.

^c “Never smoker” was defined as never having smoked the product of interest. For example, a never smoker of cigars did not smoke cigars but may have smoked pipes. “Ever smoker” was defined as ever having smoked the product of interest, in a similar manner. For this reason, cigar smoking odds ratios were adjusted for the duration of pipe smoking (and the duration of cigarette smoking among ever cigarette smokers).

^d P for linear trend was obtained from modeling the continuous forms of the frequency, duration, and cumulative variables.