Nutritional factors and gastric cancer in Zhoushan Islands, China

Table 1 Distribution of 103 cases of gastric cancer and 133 controls according to age, gender, address and selected variables

Characteristics	Cases (n = 103)	Controls (n = 133)	χ2	P
Age (yr)
Average	3 (30-85)	60 (28-82)
≤ 45	6	20
46-55	27	32
56-65	32	38
66-75	30	38
76-85	8	5	6.40	0.172
Gender
Males	81	95
Females	22	38	1.59	0.210
Present residence1
Large islands	70	76
Medium islands	17	33
Small islands	16	24	3.20	0.202
Education (yr)
<7	43	45
7-12	58	76
≥13	2	12	5.89	0.053
Economic status
Low	46	30
Medium	32	44
High	25	51	12.15	0.002
Cigarette smoking
Ever-smokers	62	70
Non-smokers	41	63	1.35	0.246
Alcohol drinking
Ever-drinkers	58	63
Non-drinkers	45	70	1.86	0.173

¹Three categories of islands were classified according to the number of permanent residents on islands: Dinghai, Putuo, and Daishan Islands, which are the three main islands in Zhoushan, predefined as the large islands; the islands on which the number of permanent residents is over 25 000, defined as the medium islands; the residual defined as the small islands.