Table 3.

Multivariable hazard ratios (HR) and 95% confidence intervals (CI) of breast cancer associated with a woman's specific type of affected relatives¹

Relative with breast cancer	Subjects	Person- Years	Cases	Adjusted2 HR (95%CI)
Affected Maternal History
No Family History (Ref.)	44,421	127,114	558	1.0
Affected mother	8,307	25,059	161	1.56 (1.31-1.86)
Affected mother's age at diagnosis (years)
≥50	5,986	18,128	112	1.49 (1.22-1.83)
<50	1,986	5,926	35	1.50 (1.07-2.12)
Affected Grandmother History
No Family History (Ref.)	44,421	127,114	558	1.0
No. of affected grandmothers
1	5,851	16,975	84	1.30 (1.03-1.64)
2	324	930	9	2.66 (1.37-5.14)
No. of affected grandmothers and age at diagnosis (years)
Only affected ≥50
1	4,211	12,240	58	1.25 (0.95-1.64)
2	171	492	6	3.46 (1.55-7.75)
At least one affected <50	1,733	4,989	28	1.48 (1.01-2.17)
Affected Sister History3
No Family History (Ref.)	32,445	92,122	390	1.0
No. of affected sisters
1	5,638	17,238	137	1.64 (1.34-2.00)
2+	578	1,917	20	2.03 (1.29-3.19)
No. of affected sisters and age at diagnosis (years)
Only affected ≥50
1	2,753	8,504	78	1.77 (1.38-2.28)
2+	224	740	10	2.49 (1.32-4.70)
At least one affected <50	2,947	8,994	59	1.50 (1.14-1.97)
Affected Aunt History4
No Family History (Ref.)	37,961	108,138	461	1.0
No. of affected aunts
1	11,792	34,958	188	1.30 (1.10-1.54)
2+	3,768	11,167	59	1.28 (0.98-1.69)
No. of affected aunts and age at diagnosis (years)
Only affected ≥50
1	5,834	17,376	100	1.38 (1.11-1.72)
2+	1,251	3,740	27	1.68 (1.14-2.48)
At least one affected <50	5,042	14,668	65	1.10 (0.85-1.43)

¹Estimated using Cox Proportional Hazards Models among women in the Group Health Breast Cancer Screening Program between June 1, 2001 and December 31, 2005

²Adjusted for age at baseline (quadratic) and stratified by source of risk factor information

³Among women with ≥1 sister who had complete sister history data

⁴Among women with ≥1 aunt who had complete aunt history data