Table 2.

Odds ratios (ORs) and 95% confidence intervals (CI) for breast cancer risk according to histologic subtype of benign breast disease and extent of atypia among participants in the Nurses’ Health Study (1976-1998) and Nurses’ Health Study II (1991-1997)

	Cases	Percent Ipsilateral*	Controls	OR (95% CI)
BBD Histologic Subtype and extent of atypia
Non-proliferative	108	51.3	680	1.0 (ref)
Proliferative without atypia	256	54.9	1035	1.6 (1.3-2.1)
AH, 1 focus†	37	62.5	66	3.8 (2.4-6.1)
AH, 2 foci	26	54.6	42	4.5 (2.6-7.7)
AH, ≥3 foci	56	59.1	74	5.3 (3.5-8.1)

^*Among cases with available laterality data (N=387).

** Adjusted for matching factors (age at breast cancer diagnosis, year of benign breast biopsy, and time since BBD biopsy) and family history of breast cancer, age at menarche, parity/age at first birth, body mass index, menopausal status/type of menopause, and duration of postmenopausal hormone use.

^†Number of cases/controls included in foci analysis (119 cases, 182 controls) does not add up to total number of cases/controls with AH (124 cases, 192 controls) due to missing foci information.

p-trend, number of foci of AH = 0.22