Abstract
False-negative mammograms are a part of any screening program and the National Breast
Screening Program in the United Kingdom is no exception. Every year, 2.5 million women
have screening mammograms in the United Kingdom. Around 8 per 1,000 women screened
are diagnosed with a breast cancer and 3 per 1,000 women will present with an interval
breast cancer following a negative screening mammogram and before their next mammogram.
Robust quality standards have to be adhered to at every stage in the screening pathway
in order to maintain the fine balance between detecting cancers early and avoiding
unnecessary false-positive results. As part of this process, there is a mandatory
requirement for screening units to review all breast cancers. We present a pictorial
illustration of the lessons learnt from such a review in this essay. The cases described
here are from one large breast screening unit in the North of England. In this unit,
30,000 to 40,000 women have a screening mammogram each year and these are all double
read by human readers. All cases requiring recall and those where there is a disagreement
between the first and second human reader go through a consensus/arbitration process
involving a minimum of two human readers. Interval cancers are identified through
a consistent process outlined by the screening program and are then subjected to a
review by a minimum of two reviewers. In this process, the reviewers have access to
the false-negative mammograms along with all priors that were available at the time
of initial read. The reviewers make a decision on whether the initial mammogram is
normal or abnormal without seeing the diagnostic mammogram with the interval cancer.
They also categorize the density of the breast and describe the mammographic abnormality
if there is any on a standardized interval cancer data collection form. Finally, they
categorize the interval cancer into one of three types—“satisfactory,” “satisfactory
with learning points,” or “unsatisfactory.”
Keywords
interval breast cancer - National Breast Screening Program - screening mammogram
