Table 1.

Risk factors for breast cancer among the 698 women with atypia from the Mayo Benign Breast Disease Cohort

VariableGroupNumberExpectedObservedSIR (95% CI)P value
Overall atypia cohortAll atypias698 (100%)331434.34 (3.66, 5.12)
Age at atypia<45100 (14.3%)3175.45 (3.17, 8.73)0.04
45-55233 (33.4%)11595.43 (4.13, 7.01)
>55365 (52.3%)19673.54 (2.74, 4.49)
Type of atypiaADH330 (47.9%)15603.93 (3.00, 5.06)0.54
ALH327 (47.5%)16754.76 (3.74, 5.97)
ADH and ALH32 (4.6%)274.36 (1.75, 8.96)
Number of atypical foci1410 (59.9%)20653.19 (2.46, 4.07)<0.001
2161 (23.5%)7405.53 (3.95, 7.53)
3+113 (16.5%)5377.61 (5.36, 10.49)
Extent of lobular involutionNone75 (11.4%)3217.66 (4.74, 11.72)<0.001
Partial428 (65.2%)21984.63 (3.76, 5.65)
Complete153 (23.3%)7141.91 (1.04, 3.20)
Family history of breast cancerNone372 (59.1%)18703.91 (3.05, 4.94)0.23
Weak151 (24%)7395.54 (3.94, 7.57)
Strong106 (16.9%)6244.19 (2.68, 6.23)
CalcificationsNO173 (24.8%)9404.63 (3.31, 6.31)0.64
YES525 (75.2%)241034·24 (3·46, 5·14)

SIR, standardized incidence ratio comparing observed number of breast cancer events to those expected based on Iowa SEER data; P-value, test for heterogeneity of SIR across levels of given characteristic. Family history criteria: strong = 1 first-degree relative (FDR) with breast cancer before age 50, or 2 or more relatives with breast cancer, with at least one a FDR; weak = any lesser degree of family history.