Invasive breast cancer and breast cancer death after non-screen detected ductal carcinoma in situ

Breast cancer screening began in the 1990s, with the aim of detecting invasive breast cancer early and reducing breast cancer deaths.1 Rates of breast cancer deaths have declined over recent decades due to a combination of better systemic treatments, increased awareness, and screening.234 However, since the introduction of screening, incidence of ductal carcinoma in situ (known as DCIS) has increased substantially, accompanied by growing concerns about overdiagnosis and overtreatment.567 Moreover, a recent meta-analysis of randomised trials evaluating cancer screening programmes questioned the net benefit of screening in reducing cancer mortality.8

Although breast cancer screening attendance is high in the UK (70%),9 a substantial number of women present with non-screen detected ductal carcinoma in situ: women too young or too old for official screening programmes, eligible women who do not attend screening, or eligible women who develop ductal carcinoma in situ between screens (interval carcinoma). In a linked paper,10 Mannu and colleagues (doi:10.1136/bmj-2023-075498) report interesting data for 27 543 …