Head and neck cancer and occupational exposure to leather dust: results from the ICARE study, a French case-control study

Table 1 Main characteristics of subjects included in the analysis and cancer subsites

	Cases (n = 2161)		Controls (n = 3555)		p-value of chi 2 test
	n	%	n	%	p-value of chi 2 test
Age at interview (years, quartiles)					0.003
Mean (SD)	57.8 (8.6)		58.5 (10.2)
< 51	467	21.6	899	25.3
51–60	767	35.5	812	22.8
59–65	508	23.5	801	22.5
≥66	419	19.4	1043	29.3
Sex					< 0.0001
Male	1862	86.2	2780	78.2
Female	299	13.8	775	21.8
Area of residence					< 0.0001
Bas-Rhin	232	10.7	469	13.2
Calvados	210	9.7	462	13.0
Doubs, Territoire de Belfort	47	2.2	143	4.0
Hérault	227	10.5	450	12.7
Isère	250	11.6	501	14.1
Loire Atlantique	359	16.6	404	11.4
Manche	238	11.0	312	8.8
Haut-Rhin	39	1.8	118	3.3
Somme	394	18.3	499	14.0
Vendée	165	7.6	197	5.5
Socioeconomic status (the longest held job)					< 0.0001
Managers	134	6.2	618	17.4
Farmers	51	2.4	197	5.5
Self-employed workers	136	6.3	177	4.9
Intermediate white-collar workers	218	10.1	695	19.5
Office and sales employees	341	15.8	672	18.9
Blue-collar workers	1241	57.4	1178	33.1
Tobacco smoking status					< 0.0001
Never smokers	110	5.1	1262	35.5
Former smokers ^a	589	27.3	1461	40.1
Current smokers	1452	67.2	820	23.1
Tobacco-smoking (pack-years, quartiles)					< 0.0001
Mean (SD)	38.3 (25.2)		13.2 (18.4)
Never smokers	110	5.1	1262	35.5
< 7	94	4.3	581	16.6
7–16	174	8.1	566	16.1
17–29	376	17.4	535	15.2
> 29	1361	62.9	566	16.1
Alcohol drinking (glass-years, quartiles)					< 0.0001
Mean (SD)	213.1 (233.6)		78.3 (120.1)
Never drinkers	103	4.8	306	8.6
< 9	149	6.9	803	22.6
9–46	174	8.1	806	22.7
47–118	378	17.5	804	22.6
> 118	1273	58.9	802	22.6
Cancer subsites^b
Oral cavity	444	20.5	–	–
Oropharynx	658	30.5	–	–
Hypopharynx	405	18.7	–	–
Oral cavity/pharynx unspecified	148	6.8	–	–
Larynx	506	23.5	–	–

^a Former smokers were subjects who had stopped smoking at least two years before the interview (controls) or diagnosis (cases)
^b Only squamous cell carcinomas were included in the study