Persistent Untreated Screening-Detected Breast Cancer: An Argument Against Delaying Screening or Increasing the Interval Between Screenings

Abstract

Purpose: The aim of this study was to investigate the natural history of untreated screen-detected breast cancer.

Methods: A prospective cohort survey of Society of Breast Imaging fellows concerning the appearance on subsequent mammography of untreated breast cancer detected on screening mammography was conducted.

Results: A representative sample of the 108 actively practicing Society of Breast Imaging fellows (n = 42 [39%]) participated, each reporting outcomes data from his or her entire screening mammography practice. Among all practices, 25,281 screen-detected invasive breast cancers and 9,360 cases of screen-detected ductal carcinoma in situ were reported over the past 10 years. Among these cancers, there were 240 cases of untreated invasive breast cancer and 239 cases of untreated ductal carcinoma in situ, among which zero were reported to have spontaneously disappeared or regressed at next mammography.

Conclusions: Among 479 untreated breast cancers detected on screening mammography, none spontaneously disappeared or regressed. An unknown percentage of these cancers represent overdiagnosis, but because all untreated screen-detected cancers were visible and suspicious for malignancy at next mammographic examination, delaying the onset of screening or increasing the interval between screenings should not reduce the frequency of overdiagnosis.

Keywords: SBI; Screening mammography; Society of Breast Imaging; breast cancer natural history; overdiagnosis; screen-detected breast cancer.