Table 2. Hypopharyngeal and laryngeal cancer risk in relation to tobacco use and alcohol drinking among men.

			Hypopharyngeal cancer			Laryngeal cancer
	N	PYs*	Case	RR	95%CI	Case	RR	95%CI
Bidi smoking				P=0.001			P<0.001
never	31277	441290	8	1	reference	11	1	reference
former	5830	70584	5	1.9	0.6-6.0	9	2.5	1.0-6.3
current	25403	347383	34	4.0	1.8-9.0	60	5.5	2.8-10.8
unknown	3043	41464	5	5.8	1.8-18.5	5	5.1	1.7-14.9
Cigarette smoking				P=0.124			P=0.013
never	29205	398841	21	1	reference	34	1	reference
former	5603	71488	3	0.6	0.2-2.0	5	0.6	0.2-1.5
current	27835	390298	26	1.6	0.9-2.8	44	1.7	1.1-2.7
unknown	2910	40093	2	1.2	0.3-5.3	2	0.9	0.2-3.6
Tobacco chewing				P>0.5			P>0.5
never	42190	582656	34	1	reference	51	1	reference
former	4383	54094	3	0.5	0.2-1.8	10	1.2	0.6-2.4
current	18568	258317	15	0.9	0.5-1.7	23	0.9	0.6-1.5
unknown	412	5653	0			1	2.5	0.3-18.1
Alcohol drinking				P>0.5			P=0.005
never	33296	454553	23	1	reference	27	1	reference
former	7857	98248	9	1.2	0.6-2.6	19	2.0	1.1-3.7
current	24399	347905	20	1.3	0.7-2.4	39	2.1	1.3-3.5
unknown	1	14	0			0

^*Person years

Relative risk was obtained from the following model:

H = H_s exp (B_iX_i), where background hazard, Hs, was stratified by attained age income and education; and X_i are categorical variables of tobacco use or alcohol drinking.

Categories for unknown were excluded when calculating p values.