Abstract
Radial scars (RS) are benign proliferative lesions associated with an increased risk of subsequent breast cancer. However, it remains unclear whether RS are an independent risk factor for breast cancer or whether their association with breast cancer is due to their common occurrence with other proliferative lesions known to increase breast cancer risk. We performed an updated analysis of the association between RS and subsequent breast cancer risk in a nested case-control study among 460 cases and 1,792 controls with benign breast disease (BBD) in the Nurses' Health Studies. Logistic regression was used to estimate associations between RS in BBD biopsy specimens and breast cancer risk, adjusted for matching factors and breast cancer risk factors, including histologic category of concurrent BBD. In multivariable models prior to adjustment for histologic category of BBD, RS were associated with a twofold increased risk of breast cancer (odds ratio (OR) = 2.0; 95 % confidence interval (95 % CI) 1.4, 2.8). This association was attenuated but still significant after adjustment for BBD histologic category (OR = 1.6; 95 % CI 1.1, 2.3). In models adjusted for BBD histologic category and other covariates, risk appeared greater among women with multiple RS (1 RS, OR = 1.5; 95 % CI 0.9, 2.3; ≥2 RS, OR = 2.7; 95 % CI 1.5, 5.0; p-heterogeneity = 0.12). There were also suggestions of a greater risk associated with RS among women age ≥50 years at biopsy (p-heterogeneity = 0.07) and for estrogen receptor-negative/progesterone receptor-negative tumors compared with other hormone receptor subtypes (p-heterogeneity = 0.19). RS appear to be an independent histologic risk factor for breast cancer. Larger studies are needed to further evaluate whether risk is increased when multiple RS are present and whether associations vary by age at biopsy or by hormone receptor status of the breast tumor.