Reply to I. JatoiWe thank Dr Jatoi 1 for highlighting additional areas of controversy regarding ductal carcinoma in situ (DCIS) in response to our article. 2 We agree that improved understanding of DCIS natural history is needed to determine the impact of its detection and treatment on invasive breast cancer (IBC) development and mortality. Many models of DCIS and IBC exist and are debated, 3,4 and the exact relationship of individual DCIS lesions with future risk of IBC remains unclear. It is precisely this inability to predict individual and lesion risk that has led to many of the challenges we face with managing DCIS.