Mammographic features of benign breast lesions and risk of subsequent breast cancer in women attending breast cancer screening

To evaluate the mammographic features in women with benign breast disease (BBD) and the risk of subsequent breast cancer according to their mammographic findings. We analyzed data from a Spanish cohort of women screened from 1995 to 2015 and followed up until December 2017 (median follow-up, 5.9 years). We included 10,650 women who had both histologically confirmed BBD and mammographic findings. We evaluated proliferative and nonproliferative BBD subtypes, and their mammographic features: architectural distortion, asymmetries, calcifications, masses, and multiple findings. The adjusted hazard ratios (aHR) and 95% confidence intervals (95% CI) for breast cancer were estimated using a Cox proportional hazards model. We plotted the adjusted cumulative incidence curves. Calcifications were more frequent in proliferative disease with atypia (43.9%) than without atypia (36.8%) or nonproliferative disease (22.2%; p value < 0.05). Masses were more frequent in nonproliferative lesions (59.1%) than in proliferative lesions without atypia (35.1%) or with atypia (30.0%; p value < 0.05). Multiple findings and architectural distortion were more likely in proliferative disease (16.1% and 4.7%) than in nonproliferative disease (12.8% and 1.9%). Subsequent breast cancer occurred in 268 (2.5%) women. Compared with women who had masses, the highest risk of subsequent breast cancer was found in those with architectural distortions (aHR, 2.21; 95% CI, 1.16-4.22), followed by those with multiple findings (aHR, 1.89; 95% CI, 1.34-2.66), asymmetries (aHR, 1.66; 95% CI, 0.84-3.28), and calcifications (aHR, 1.60; 95% CI, 1.21-2.12). BBD subtypes showed distinct mammographic findings. The risk of subsequent breast cancer was high in those who have shown architectural distortion, multiple findings, asymmetries, and calcifications than in women with masses. The presence of mammographic findings in women attending breast cancer screening helps clinicians to assess women with benign breast disease (BBD). Calcifications were frequent in BBDs with atypia, which are the ones with a high breast cancer risk, while masses were common in low-risk BBDs. The excess risk of subsequent breast cancer in women with BBD was higher in those who showed architectural distortion compared to those with masses.