Table 1.

Selected characteristics of the study population (N = 826)

	Cases (n = 390)		Controls (n = 436)		P values
	N	%	N	%
Sexa					< 0.001
Female	319	81.8	307	70.6
Male	71	18.2	128	29.4
Age (years)					0.002
< 40	69	17.7	48	11.0
40-	93	23.9	109	25.0
50-	126	32.3	121	27.8
≥ 60	102	26.2	158	36.2
Race					0.58
White	351	90.0	397	91.1
Black	16	4.1	20	4.6
Others	23	5.9	19	4.4
Education					0.006
High school or less	108	27.7	77	17.7
College or trade school	179	45.9	226	51.8
Graduate school	91	23.3	121	27.8
Missing	12		12
Body mass index (kg/m2)					< 0.001
< 24.9	128	32.8	182	41.7
24.9-29.9	119	30.5	150	34.4
> 30	143	36.7	104	23.9
Family income					0.80
Low	107	40.2	120	39.1
Medium	68	25.6	74	24.1
High	91	34.2	113	26.8
Confidential or unknown	124		129
Smokingb					0.46
No	274	70.3	296	67.9
Yes	116	29.8	140	32.1
Alcohol consumptionc					< 0.001
No	224	57.4	197	45.2
Yes	166	42.6	239	54.8
Family history of thyroid cancer					0.001
No	331	84.9	401	92.0
Yes	59	15.1	35	8.0

^aTotal number does not add up due to missing value.

^bEver smoking was defined as ever smoked a total of 100 cigarettes or more.

^cEver alcohol consumption was defined as ever had more than 12 drinks of alcoholic beverages such as beer, wine, or liquor.

1 drink of beer = 1 can or bottle; 1 drink of wine = 14 oz glass; 1 drink of liquor = 1 shot.