Table 1.

Distribution of Patients for the Gail Model Risk Factors Among White Women in NIH-AARP and PLCO

Variable	NIH-AARP (n = 181,979)				PLCO (n = 64,868)
	Patients		Total		Patients		Total
	No.	%	No.	%	No.	%	No.	%
Age at menarche, years
7-11	1,253	22.1	39,026	21.5	487	21.9	13,036	20.1
12-13	3,180	56.1	101,178	55.6	1,169	52.6	34,094	54.1
≥ 14*	1,232	21.8	41,775	23.0	567	25.5	16,738	25.8
No. of first-degree relatives with breast cancer and age at first birth < 20 years†
0‡	672	11.9	27,522	15.1	233	10.5	9,288	14.3
1	130	2.3	3,800	2.1	47	2.1	1,342	2.1
≥ 2	4	0.1	201	0.1	6	0.3	145	0.2
No. of first-degree relatives with breast cancer and age at first birth 20-24 years
0‡	1,948	34.4	71,316	39.2	810	36.4	26,606	41.0
1	427	7.5	9,788	5.4	178	8.0	3,928	6.1
≥ 2	35	0.6	537	0.3	31	1.4	404	0.6
No. of first-degree relatives with breast cancer and age at first birth 25-29 years or nulliparous
0‡	1,673	29.5	51,084	28.1	603	27.1	16,122	24.9
1	347	6.1	7,045	3.9	105	4.7	2,458	3.8
≥ 2	33	0.6	369	0.2	16	0.7	212	0.3
No. of first-degree relatives with breast cancer and age at first birth ≥ 30 years
0‡	335	5.9	9,018	5.0	167	7.5	3,777	5.8
1	59	1.0	1,231	0.7	24	1.1	531	0.8
≥ 2	2	0.04	68	0.0	3	0.1	55	0.1
No. of breast biopsies in age ≥ 50 years
0§	3,870	68.3	137,836	75.7
1	1,134	20.0	28,845	15.9
≥ 2	661	11.7	15,298	8.4

Abbreviations: NIH-AARP, National Institutes of Health–AARP Diet and Health Study; PLCO, Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.

^*Includes unknown age at menarche.

^†Includes unknown age at first birth.

^‡Includes unknown number of first-degree relatives with breast cancer.

^§Includes unknown number of breast biopsies.