Background
Based on its cytologic features, and its co-occurrence with atypical hyperplasia and breast cancer, flat epithelial atypia (FEA) has been proposed as a precursor lesion on the pathway to breast cancer development. It is often referred to as an “atypical” or high-risk lesion. However, the long term risk of breast cancer in women with FEA is undefined.
Methods
Biopsies with FEA were identified in excisional breast biopsies in the Mayo Clinic Benign Breast Disease (BBD) Cohort, which includes 11,591 women who had benign biopsies at Mayo-Rochester 1967–2001. Breast cancer risk of FEA, non-proliferative, proliferative and atypical hyperplasia (AH) subsets was assessed using standardized incidence ratios (SIRs), relative to the Iowa Surveillance, Epidemiology, and End Results registry.
Results
FEA was identified in 282 women (2.4%); 130 had associated AH (46%) and 152 (54%) were classified as proliferative disease without atypia (PDWA). With median follow-up of 16.8 years, the SIR for breast cancer in AH + FEA was 4.74 (95% CI: 3.17–6.81) versus 4.23 (3.44–5.13) for AH without FEA (p=0.59). The SIR for PDWA + FEA was 2.04 (95% CI: 1.23–3.19) versus 1.90 (1.72–2.09) for PDWA without FEA (p=0.76).
Conclusions
FEA is an uncommon finding in women with BBD. FEA does not convey independent risk of breast cancer beyond that of the associated PDWA or AH.