Table 1.

Summary of study population characteristics by age^*

	Age category, y
Characteristic	<30	30-34	35-39	40-49	P
Menopausal status					<.001
Premenopausal	124	114	122	171
Postmenopausal	0	5	15	34
Perimenopausal	0	0	1	4
Not recorded	0	0	1	0
Screening breast EIS result					.4515
Negative	120	117	132	199
Positive	4	2	7	10
Clinical breast examination result					.0077
No findings	78	88	77	141
Not suspicious	45	28	52	57
Suspicious	1	3	10	11
Hormone replacement therapy					.0263
Current	0	2	2	11
Past	0	1	0	3
Never	124	116	137	195
Mammogram results					<.001
BIRADS 0	1	0	3	10
BIRADS I or II	6	16	61	109
BIRADS III	1	6	8	21
BIRADS IV	0	2	10	23
BIRADS V	0	1	2	1
No mammogram	116	94	55	45
Breast biopsy category					.4076
Benign, no atypia	19	12	27	34
Premalignant	1	0	2	4
Infiltrating cancer or DCIS	0	1	2	3
No biopsy (assumed benign)	104	106	108	168
Family history category					.4080
One first degree	9	12	20	18
One second degree	22	24	24	38
One first and one or more second degree	9	9	12	11
Two or more first degree	0	1	4	2
Two or more second degree	7	12	10	21
No significant family history	77	61	69	119
Gail model 5-year risk category, %					<.001
<1.66	108	119	132	175
≥1.66	0	0	3	27

*BIRADS indicates Breast Imaging Reporting and Data System; EIS, electrical impedance scanning; and ductal carcinoma in situ.