Breast cancer screening
Females aged 50–69 years are invited every 3 years for screening by a craniocaudal and a mediolateral oblique mammogram. Screening aims to detect tumours of <1 cm size before they become palpable. If identified, a stereotactic needle core biopsy can be performed to obtain tissue for histology. A hooked wire can be inserted under radiological guidance into the lesion prior to surgery. The lump can then be identified and either undergo excision biopsy or wide local excision with the removal of a margin of surrounding normal tissue. If the histology demonstrates malignancy further treatments for breast cancer may be required.
The evidence of the breast cancer screening programme is difficult to assess. Trials have investigated the effect of screening on mortality, but as the range of mortality rates exceed the reduction of mortality by screening it is difficult to demonstrate a statistical benefit. Overall it appears that one woman in every 1000 who undergoes breast screening may be prevented from dying from breast cancer. This must be balanced against false positive screening results and unnecessary biopsies, which are the cause of significant patient morbidity.