Monday, December 7, 2015

SBI response to U.K. study that found DCIS detected by screening suggests that detection and treatment of DCIS is worthwhile in prevention of future invasive disease

"Mammography screening began in the mid 1980's and soon after, for the first time in 50 years, the death rate from breast cancer began to fall.  As more and more women have participated in screening the death rate has now declined so that there are 36% fewer women dying each year than would have died had screening and improvements in therapy not been available.  The importance of early detection is seen in a study at two of the major Harvard Teaching hospitals where more than 70% of women who died from breast cancer, despite access to the latest therapies, were among the 20% of women who are not participating in screening.  There are no good national statistics on mammography and breast cancer deaths, but the Harvard study suggests that many of the 40,000 deaths from breast cancer that still occur each year are due to women not participating in screening.

One of the major questions that has been raised in an effort to reduce access to screening is that screening detects the earliest form of breast cancer known as Ductal Carcinoma in Situ (DCIS). The recent paper by Duffy et al showing that the treatment of DCIS has reduced the incidence of invasive breast cancers in the UK has also been suggested in the U.S.  In his critique of the New England Journal of Medicine paper that falsely claimed massive overdiagnosis of breast cancer in the U.S., Kopans showed that not only was there no "overdiagnosis" of invasive cancers, but if data derived projections of invasive cancers were used, there were actually fewer invasive cancers thatnwould have been expected in 2008.  Kopans speculated that this was due to removal of DCIS over the preceding years.  Helvie and Hendrick arrived at similar conclusions.

A reduction in invasive cancers is probably part of the reduction in breast cancer deaths that has occurred since 1990.  Instead of reducing access to screening to prevent "overtreatment" of DCIS, screening should be encouraged to save lives while therapists determine how best to treat these very early lesions.

Categories: Screening Mammography Resources, 2015, December, News, Research and CareNumber of views: 8747


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