Table 3.

Odds ratios (OR) and 95% confidence intervals (CI) for lobule type and breast cancer risk among participants in the Nurses’ Health Study (1988–1994) and Nurses’ Health Study II (1991–1995), stratified by histologic category of BBD

	Cases	Controls	OR (95% CI)*
Nonproliferative
No type 1 lobules or mixed lobule types	31	199	1.0 (REF)
Predominant type 1, no type 3 lobules	16	132	0.73 (0.36–1.50)
Proliferative with no atypia
No type 1 lobules or mixed lobule types	73	334	1.0 (REF)
Predominant type 1, no type 3 lobules	24	150	0.80 (0.47–1.35)
Atypical hyperplasia
No type 1 lobules or mixed lobule types	42	61	1.0 (REF)
Predominant type 1, no type 3 lobules	14	39	0.61 (0.28–1.35)
P for interaction between lobule type and BBD category = 0.67

^*Adjusted for age, year of BBD, and time since benign biopsy.