Breast screening programme effective in preventing some invasive cancers

Ductal carcinoma in situ (DCIS) is described as a very early form of breast cancer, where cancer cells are present in milk ducts, but have not yet invaded the surrounding breast tissue. Around 4,800 people are diagnosed with DCIS in the UK each year and the main form of treatment is surgery followed by radiotherapy.
Ongoing public debate about the harm caused by mammography screening through over-diagnosis has led to controversy over the value of screening for and treatment of DCIS. A major question has been the extent to which diagnosis and treatment of DCIS may prevent the occurrence of invasive breast cancer in the future.
The researchers analysed data on 5,243,658 women aged 50-64 who were screened over a four year period across 84 screening units in the UK