Cheasley D, et al. - Since understanding the molecular differences between interval breast cancer (IBC) and screen-detected breast cancers (SDBC) could improve mammographic screening and management options, researchers evaluated germline and somatic genomic aberrations using the Lifepool cohort of >54,000 women participating in mammographic screening programs. They identified 930 breast cancer (BC) cases with screening status (726 SDBC and 204 IBC). For this investigation, they recorded clinico-pathological and family history information. Compared to SDBC, diagnostic and tumor characteristics correlated with worse prognosis were significantly related to IBCs at a younger age. The frequency of germline mutations in IBC compared to SDBC was higher, but not statistically significant. Although IBCs are clinically more aggressive than SDBC, they do not represent a unique molecular class of invasive BC when combined with confounding clinical-pathological characteristics, but may be the result of tumor initiation and mammographic screening.