Table 2. Odds ratio of kidney cancer for tobacco smoking.

	Men				Women				Total
	Cases	Controls	ORa	95% CI	Cases	Controls	ORa	95% CI	Cases	Controls	ORa	95% CI
Smoking	N	N			N	N			N	N
Never smokers	170	232	1.00	Refb	340	368	1.00	Ref	510	600	1.00	Ref
Former smokers	204	302	0.89	0.68, 1.17	47	51	1.07	0.69, 1.67	251	353	0.88	0.71, 1.11
Current smokers	273	416	0.99	0.76, 1.29	60	105	0.70	0.48, 1.02	333	521	0.87	0.71, 1.07
Never smokers	170	232	1.00	Ref	340	368	1.00	Ref	510	600	1.00	Ref
<17 packyears	150	221	0.94	0.70, 1.26	62	97	0.76	0.52, 1.11	212	318	0.85	0.67, 1.06
17–31 packyears	161	234	1.00	0.75, 1.34	32	39	0.99	0.59, 1.65	193	273	0.95	0.74, 1.21
>31 packyears	165	261	0.89	0.67, 1.19	13	19	0.85	0.40, 1.78	178	280	0.85	0.66, 1.09
			P-value for trend 0.49				P-value for trend 0.34				P-value for trend 0.19

^aAdjusted for age, body mass index, history of hypertension and country.

^bRef=reference category.