Table 1.

Epidemiologic and Tumor Characteristics at Time of Diagnosis of the First Breast Cancer

Characteristic	CHEK2*1100delC Genotype				P
	Noncarriers		Heterozygotes
	No.	%	No.	%
No. of patients with breast cancer	25,112		459
Age at diagnosis, years					< .001
Median	54		50
IQR	46-63		43-59
Year of diagnosis	2000		2000		.49
IQR	1996-2003		1997-2004
Familial history					< .001
Negative	6,652	26	70	15
Positive	2,531	10	60	13
Missing	15,929	63	329	72
Body mass index, kg/m2					.94
< 18.5	347	1	5	1
18.5-24.9	9,136	36	126	27
25.0-29.9	6,479	26	89	19
≥ 30.0	3,478	14	43	9
Missing	5,672	23	196	43
Menopausal status					< .001
Premenopausal	7,231	29	142	31
Postmenopausal	13,101	52	142	31
Missing	4,780	19	175	38
Tumor size, mm					.65
< 20	10,769	43	182	40
20-50	7,894	31	148	32
> 50	717	3	13	3
Missing	5,732	23	116	25
Lymph node status					.60
Negative	8,853	35	141	31
Positive	6,451	26	110	24
Missing	9,808	39	208	45
Tumor grade					.13
Well differentiated	4,641	18	71	15
Moderately differentiated	9,634	38	191	42
Poorly differentiated/undifferentiated	6,215	25	104	23
Missing	4,622	18	93	20
Estrogen receptor status					< .001
Positive	14,234	57	290	63
Negative	4,320	17	41	9
Missing	6,558	26	128	28
Progesterone receptor status
Positive	10,739	43	212	46	.01
Negative	5,864	23	83	18
Missing	8,509	34	164	36
Human epidermal growth factor receptor 2
Positive	1,577	6	34	7	.69
Negative	6,420	26	128	28
Missing	17,115	68	297	65

NOTE. P values were calculated by using χ² test for categorical characteristics and Kruskal-Wallis one-way analysis of variance tests for age and calendar year of diagnosis, excluding patients with breast cancer who had missing values.

Abbreviation: IQR, interquartile range.