Table 2.

Relationship between Family History of Breast Cancer and Risk of Second Breast Cancer Among Women with Carcinoma In Situ of the Breast

	Controls	All Cases		Invasive Cases
	n(%)	n(%)	OR (95% CI)1	n(%)	OR (95% CI)1
DCIS and LCIS (n=1,533)
1st Degree Family History of Breast Cancer
No	729 (73.3)	365 (67.7)	1 [Ref]	247 (67.1)	1 [Ref]
Yes	265 (26.7)	174 (32.3)	1.33 (1.05, 1.69)	121 (32.9)	1.37 (1.02, 1.84)
# of First Degree Relatives with Breast Cancer
0	729 (73.6)	365 (67.8)	1 [Ref]	247 (67.1)	1 [Ref]
1	224 (22.6)	141 (26.2)	1.25 (0.96, 1.62)	100 (27.2)	1.33 (0.97, 1.82)
2+	37 (3.7)	32 (6.0)	1.94 (1.15, 3.28)	21 (5.7)	1.87 (0.97, 3.60)
Age at Diagnosis of 1st Degree Family Member
No history	729 (74.5)	365 (69.0)	1 [Ref]	247 (68.4)	1 [Ref]
≥50	176 (18.0)	98 (18.5)	1.11 (0.83, 1.49)	66 (18.3)	1.20 (0.84, 1.73)
<50	73 (7.5)	66 (12.5)	1.78 (1.24, 2.57)	48 (13.3)	1.68 (1.09, 2.58)
DCIS Only (n=1,333)
1st Degree Family History of Breast Cancer
No	638 (73.3)	318 (68.8)	1 [Ref]	213 (68.1)	1 [Ref]
Yes	233 (26.8)	144 (31.2)	1.26 (0.97, 1.63)	100 (32.0)	1.30 (0.94, 1.79)
# of First Degree Relatives with Breast Cancer
0	638 (73.5)	318 (69.0)	1 [Ref]	213 (68.1)	1 [Ref]
1	195 (22.5)	115 (25.0)	1.18 (0.89, 1.56)	81 (25.9)	1.25 (0.88, 1.77)
2+	35 (4.0)	28 (6.1)	1.78 (1.02, 3.10)	19 (6.1)	1.73 (0.87, 3.43)
Age at Diagnosis of 1st Degree Family Member
No history	638 (74.5)	318 (70.2)	1 [Ref]	213 (69.4)	1 [Ref]
≥50	152 (17.7)	82 (18.1)	1.10 (0.80, 1.50)	56 (18.2)	1.23 (0.83, 1.81)
<50	67 (7.8)	53 (11.7)	1.56 (1.05, 2.33)	38 (12.4)	1.42 (0.89, 2.28)

Notes: 5 participants missing information on # of first degree relatives and 26 missing information on age of family member

¹Models were implicitly adjusted for matching factors, no further adjustment