Screening for and treatment of DCIS prevents subsequent IDC

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http://medicalxpress.com/news/2015-12-breast-scree...

http://www.thelancet.com/journals/lanonc/article/P...(15)00446-5/fulltext

http://www.thelancet.com/journals/lanonc/article/P...(15)00446-5/abstract

Screening for and treatment of an early form of breast cancer has been found to prevent subsequent invasive cancer, according to research led by Queen Mary University of London (QMUL).......

'Ongoing public debate about the harm caused by mammography screening through overdiagnosis 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's National Health Service Breast Screening Programme in England, Wales and Northern Ireland.

They found that increased prior screen detection of DCIS was associated with a reduction in invasive cancers occurring in the subsequent three-year interval. In 90 per cent of the screening units, for every three screen-detected cases of DCIS, there was one fewer case of invasive cancer in the following three years. As the study is based on screening unit level data, it cannot give definitive proof of progressive potential or otherwise of individual DCIS cases.

Lead researcher Professor Stephen Duffy from QMUL said: "There has been controversy over whether ductal carcinoma in situ will ever become invasive cancer. This is the first study from the screening programme which suggests that a substantial proportion of DCIS will become invasive if untreated, and it is therefore worth detecting and treating early. People can be reassured that detection of DCIS in the breast screening programme is benefitting the patients."....'