Retrospective study of risk factors and mortality among women with interval breast cancer versus screen-detected breast cancer

The risk factors for interval breast cancer (IBC; diagnosed within 6 to 24 months after a negative screening result) compared with screen-detected breast cancer (SBC; diagnosed within 6 monhts after a positive screening result) and their association with mortality outcomes are not clear. A retrospective cohort study based on data from the Korean Health Insurance Service Database included 18,194 women who underwent mammographic breast cancer screening. The study found that breast density, obesity, and use of hormone replacement therapy were associated with IBC compared with SBC. Overall mortality of IBC was comparable with that of SBC, although total mortality and breast cancer-related mortality of IBC diagnosed between 6 and 12 months after screening was higher than that of SBC. The authors conclude that additional research is warranted to determine whether a shorter interscreening period and new screening strategies are needed for women with risk factors for IBC.